New Art Morrison IRS

[jtwoods4]

Guys you definitely need to check out the link below. This new setup was just released by Art Morrison and it looks like they are the first company to design an IRS system that may out perform the 3 and 4 link straight axle setups. Let the comments begin!!!!!

http://www.artmorrison.com/multi-link-IRS.php

[Build-It-Break-It]

It looks pretty but it all boils down to price point. If its anywhere near $9k you still have to factor in front suspension ,which from them is another $7k . That's the price of a complete frame swap from places like RS and Swartz. Plus its nothing new, places like Heidts etc already make a irs and people have been making there own for years now. I'd really like to see some real world data to back it up, not just because someone says its the best new thing. Numbers don't lie, but it is a really nice professional looking set up.

[rchaskin]

Looks nice. Is that a D60 diff?

[jtwoods4]

Yeah I hear ya Build It Break It. However, this AMEs model stands apart from other IRS systems I have seen. The engineering and design looks to be better.

For some real world testing take a look at the new Super Chevy magazine. the AME's test car goes head to head with the new Camaro SS on some track tests and it outperforms it.

[andrewb70]

Looks nice. Is that a D60 diff?

Yes...

http://www.strangeengineering.net/high-performance-street/complete-rear-end-assemblies/s60/independent-s60-camaro-complete-rear-end-assembly.html

I just called and talked to AM. It can also use the stock 5th Gen Camaro rear end. The rear spindles are also 5th Gen Camaro. Axles look like they are from The DriveShaft shop.

Andrew

[dontlifttoshift]

Pricing?

[andrewb70]

Pricing?

They said a couple of weeks. I suspect it will be somewhere between $7500-8000. The Strange diff is over $3k...plus axles...plus spindles...plus all the control arms...etc...

Andrew

[dontlifttoshift]

8K would be very reasonable. Wonder how well it puts power down?

[jtwoods4]

13k is what it said in the recent super Chevy magazine.

[DJW32]

Yes...

http://www.strangeengineering.net/high-performance-street/complete-rear-end-assemblies/s60/independent-s60-camaro-complete-rear-end-assembly.html

I just called and talked to AM. It can also use the stock 5th Gen Camaro rear end. The rear spindles are also 5th Gen Camaro. Axles look like they are from The DriveShaft shop.

Andrew

The stock 5th gen camaro diff is not as strong as some think. A lot of 5th gen owners replace the stock diff when they add any real tq/hp to the car.

Overall, the rear looks very promising.

[andrewb70]

13k is what it said in the recent super Chevy magazine.

That seems pretty steep...I guess we will have to see.

Andrew

[andrewb70]

The stock 5th gen camaro diff is not as strong as some think. A lot of 5th gen owners replace the stock diff when they add any real tq/hp to the car.

Overall, the rear looks very promising.

Yes, but the ZL1 rear should be much stronger and has a 9.9" ring gear.

I wonder why they chose the 5th gen route and not 9". The IRS 9" solutions seem to be less expensive.

Also, since this kit uses 5th Gen Camaro hubs, the bolt pattern is 5x120mm.

Andrew

[Samckitt]

Pretty cool, but out of my price range im sure

[Build-It-Break-It]

Like I said earlier, if it is 13k just for just the rear end it wouldn't make sense for the average Joe. Factor in $7k for AM front end and that's $20k..... Its a nice set up but doesn't seem practical price wise. Nice to look at tho

[Schwartz Performance]

No aftermarket IRS out there is catered toward the "average joe" price wise.. Gotta pay to play! :)

Just part out an RX7 or a Tbird!

-Dale

[Build-It-Break-It]

I'm not saying give it away but at a price point of $8k for a complete kit seems more reasonable is all....

[Samckitt]

If I can only find CAD models of rear C5 up Vette suspension parts & mount points........

[David Pozzi]

The rear diff is an S-60 9.75" ring gear Dana by Strange in their custom aluminum casting. I believe it's stronger than a Ford 9". The overall layout is close to a 5th gen Camaro, uses fifth gen aluminum outer carriers (castings), but they are machined to take the stronger/larger ZR1 bearing units. The half-shafts are Drive Shaft Shop 5th gen beef up units rated for over 1400hp.

It is amazing to drive!

[Nothingface5384]

this is just for the F bodies? which im sure will migrate down to X-bodies or are they also going to be first it make IRS for A/G bodies too ?

[andrewb70]

this is just for the F bodies? which im sure will migrate down to X-bodies or are they also going to be first it make IRS for A/G bodies too ?

It will be an option for all of their frames.

Andrew

[andrewb70]

....

It is amazing to drive!

Care to elaborate some more?

Andrew

[David Pozzi]

I only drove it a little around the pits & a short spin around the skid pad. It has adjustable amounts of rear-steer which helps the car turn more easily without sliding the rear around as much as a stick axle. When you initiate a turn, you can feel the rear steer out just a little like its set up with some oversteer, but you can floor the throttle & the rear just grabs & goes. Others tried to spin it out & it really didn't want to with the amount of power the LS1 had. Mary loved the way it handled around the road course!
Mary & I each have a system on order, so we'll know a lot more in a little while...

I don't know the exact number, but I'd guess this system has 100 to 150 lbs less unsprung weight, plus the benefit of modest neg rear camber gain when cornering. Over bumps, it's going to be way smoother.

[HellPhish89]

nice looking setup.. gives me ideas too for my own..

no in board brakes (thank god), looks like very simple mounting, beautiful engineering.. etc. one strange question though... can someone point out where the shocks mount on this thing?

[Build-It-Break-It]

Here's a YouTube video. You can see the mounting location and they describe the set up a little.


https://youtu.be/AkKvcQyRWUg

[rchaskin]

...... can someone point out where the shocks mount on this thing.....

They are invisible....LOL.
I looked at the brochure at least three times, and never noticed that the coilovers were not in it.......

[andrewb70]

They are invisible....LOL.
I looked at the brochure at least three times, and never noticed that the coilovers were not in it.......

Shocks mount at the rear of the lower control arm.

Andrew

[Cdog]

Looks Awesome! I’m a AM kool aid drinker for sure. The price however is nuts!

[Samckitt]

The rear diff is an S-60 9.75" ring gear Dana by Strange in their custom aluminum casting. I believe it's stronger than a Ford 9". The overall layout is close to a 5th gen Camaro, uses fifth gen aluminum outer carriers (castings), but they are machined to take the stronger/larger ZR1 bearing units. The half-shafts are Drive Shaft Shop 5th gen beef up units rated for over 1400hp.

It is amazing to drive!

What are the spindles/knuckles? Is that what you are calling he Camaro outer carriers?

[jtwoods4]

yeah the entire setup is beautiful but the price is ridiculous

[jtwoods4]

Sam you actually own one of these?????!!!!!!!!

[Samckitt]

Sam you actually own one of these?????!!!!!!!!

Me? Pfft, I wish.

[jtwoods4]

David I see that you have a system on order.... nice. will these fit on a 70 Trans Am f body?

[dhutton]

yeah the entire setup is beautiful but the price is ridiculous

I think the Roadster Shop IRS may cost even more.

[dontlifttoshift]

RS base is $8,995, the sky is the limit after that if you start adding options.

[dhutton]

RS base is $8,995, the sky is the limit after that if you start adding options.

Vehicle specific frame rails are $2500 and the center section $1500 which gets you to $13000 real fast.

[David Pozzi]

David I see that you have a system on order.... nice. will these fit on a 70 Trans Am f body?

Yes, they make a second gen version.

[David Pozzi]

What are the spindles/knuckles? Is that what you are calling he Camaro outer carriers?

Fifth gen Camaro outer castings. I don't know what GM calls them - the part the suspension links connect to. They slightly bore them to accept ZR1 Corvette bearing units.

[DJW32]

Yes, they make a second gen version.

David,
Is Mary removing her hotchkis rear for the AM IRS?

[andrewb70]

Fifth gen Camaro outer castings. I don't know what GM calls them - the part the suspension links connect to. They slightly bore them to accept ZR1 Corvette bearing units.

I suspect they call them spindles? Since they are modifying them to use ZR1 (is that the same as the SKF race hubs?) then this solves the issue of the bolt pattern and hub register. Well done of AM to address this in a creative way.

For those are are complaining about the price, you have to step back and look at the components that are being used. The diff case alone is over $3K, add to that the axles, and you are easily over $5k. The spindles from GM can't be cheap, add machining to accept the ZR1 hubs, plus the hubs ($750 for the pair), I bet we are over $7k now in components, maybe $8k...

Now we have to actually buy the metal to build the thing and have to little left over to make it all worthwhile.

I am eager to hear more real life reviews.

Andrew

[David Pozzi]

David,
Is Mary removing her hotchkis rear for the AM IRS?

Yes

[Nothingface5384]

Yes

Talk about unbeatable lol
Best setup for the best driver :-)

[j-c-c]

From what little I can see from the brochure, it looks robust, I like, not sure why the the 9" was not the base rear end, maybe offered later, the Heidts etc rears always seem more for looks then function, and anyone in the high HP drag rears is not going IRS anyway. $8k will sell a lot IRS, $13K not so much. Are brakes inboard? Sway bar?

[David Pozzi]

From what little I can see from the brochure, it looks robust, I like, not sure why the the 9" was not the base rear end, maybe offered later, the Heidts etc rears always seem more for looks then function, and anyone in the high HP drag rears is not going IRS anyway. $8k will sell a lot IRS, $13K not so much. Are brakes inboard? Sway bar?

Brakes are outboard, same as a fifth gen Camaro. I wouldn't get one if it had inboard brakes, - too hard to cool. Sway bar is adjustable, three holes, I think.

[andrewb70]

Ultimately, the customers will decide if the $13k price is too much or not, but here is how I see it. The only fair way to compare this rear end is to compare with a solid axle suspension system that has similar features.

The Speed Tech Chicane solid axle is such a system. It uses a floating axle design with ZR1 hubs on a 9" housing. It retails for $5500. To it you must add a carrier, diff, and gears. Let's say another $2000. So we are up to $7500.

Now we need to add a suspension system. There are a dozen options but for the sake of comparison let's use the DSE Quadra-Link. It sells for $2725 with the sway bar option. So that's a total of $10,225.

Now you have to ask if having an IRS is worth an extra $2775...

One thing that I would want to know more about is how the handling characteristics change with rear end width. Is wider better for handling?

Andrew

[David Pozzi]

Andrew, wider track width is better for handling on a road course for sure. It also is for autocross but extra width can make it tougher to clear the cones in the tighter turns.

[Whistler]

This is true , but keep in mind the considerable amount more that a 5th gen weighs in comparison to the cars these rear diffs will be used in. Thats huge when debating the amount of power it will take before needing an upgrade.


The stock 5th gen camaro diff is not as strong as some think. A lot of 5th gen owners replace the stock diff when they add any real tq/hp to the car.

Overall, the rear looks very promising.

[David Pozzi]

Here's a quick shot of it.

[killer69]

Ultimately, the customers will decide if the $13k price is too much or not, but here is how I see it. The only fair way to compare this rear end is to compare with a solid axle suspension system that has similar features.

The Speed Tech Chicane solid axle is such a system. It uses a floating axle design with ZR1 hubs on a 9" housing. It retails for $5500. To it you must add a carrier, diff, and gears. Let's say another $2000. So we are up to $7500.


I just want to clarify......... the 5500.00 INCLUDES the Center section with a Trutrack and Gears. Lets keep the information correct when doing comparisons so that people can make informed buying decisions .

thank you

[jtwoods4]

Here's a quick shot of it.

that's great thank you David! would you mind taking photos of the installation process and any issues you encounter?

[David Pozzi]

Mary will write up an install feature with photos for Super Chevy. I need to see how that impacts what I post here.
With some other chassis companies offering IRS, it's a smart move for Art Morrison to have it as an option on their chassis line.

[killer69]

Cant Be any good it doesn't have a watts link!!! lol

[j-c-c]

I'm sure there is a clearance reason, but why are the UCA bent, what do they need to clear? Same for upper rear cross member? Is there a swaybar in this package, and any pics from the rear?

[andrewb70]

[QUOTE=andrewb70;1048131]Ultimately, the customers will decide if the $13k price is too much or not, but here is how I see it. The only fair way to compare this rear end is to compare with a solid axle suspension system that has similar features.

The Speed Tech Chicane solid axle is such a system. It uses a floating axle design with ZR1 hubs on a 9" housing. It retails for $5500. To it you must add a carrier, diff, and gears. Let's say another $2000. So we are up to $7500.


I just want to clarify......... the 5500.00 INCLUDES the Center section with a Trutrack and Gears. Lets keep the information correct when doing comparisons so that people can make informed buying decisions .

thank you

My apologies. Your website wasn't super clear on whether the carrier was included or not, or I just missed that point.

Andrew

[killer69]

[QUOTE=killer69;1049878]

My apologies. Your website wasn't super clear on whether the carrier was included or not, or I just missed that point.

Andrew

no big deal just trying to keep it real.

[CTSV]

AM sent me a catalog last week and I saw this system on the cover, it does look nice and very well built but a few things i do not like. In their catalog they mention that the design was influence by the Infiniti, BMW, Ferrari etc but after watching the video Popular Hotrod did it seems its clearly based of the 5th Gen Camaro.

I had owned 2, 5th Gen Camaros and i will tell you one car was a flat our track car and the other was a Zl1. I hated both cars because on the standard not ZL1 car the rear geometry is crazy and you always have badly pitched CV joints when you lower the car down. We tore up axles, CV and differentials like crazy. We then switched to the Ford 9 inch and we still kept breaking CV because there was no way to take the negative CV angle out when the car was at ride height. Another characteristic of the 5th Gen is the back end would bounce often under load and even with tripple adjustable Eibach or Kw coilovers we never were able to dial this out. We worked with lots of aftermarket companies and it just was a inherent design of that rear IRS. My ZL1 was much more planted and GM changed a few things around by moving to a new rear housing which helped with the CV angles and the Mag shocks on the Zl1 were incredible. I got tired of breaking parts everytime i drove the car hard and now moved on. You gotta wonder why so many low mile 5th Gen that are modified are for sale any given time. Speak to the guys who race the 5th Gen in the Rolex series and they will confirm all the parts failures after each race.

this IRS stuff is cool but still nobody really has proved this to be better than the DSE Quadralink or other stuff on the market for our cars and still DSE cars seem always at the top of the list at every event. Until results are really proven id stick with a 4 link for now because the investment is serious do so one of these kits.

[Cdog]

Here's a quick shot of it.




Where do the shocks mount?

[David Pozzi]

I'm sure there is a clearance reason, but why are the UCA bent, what do they need to clear? Same for upper rear cross member? Is there a swaybar in this package, and any pics from the rear?

The uppers are bent to clear the factory frame rails in bump.
There is a sway bar, we don't have it yet.
The dip helps support the rear diff mounting.

[David Pozzi]

AM sent me a catalog last week and I saw this system on the cover, it does look nice and very well built but a few things i do not like. In their catalog they mention that the design was influence by the Infiniti, BMW, Ferrari etc but after watching the video Popular Hotrod did it seems its clearly based of the 5th Gen Camaro.

I had owned 2, 5th Gen Camaros and i will tell you one car was a flat our track car and the other was a Zl1. I hated both cars because on the standard not ZL1 car the rear geometry is crazy and you always have badly pitched CV joints when you lower the car down. We tore up axles, CV and differentials like crazy. We then switched to the Ford 9 inch and we still kept breaking CV because there was no way to take the negative CV angle out when the car was at ride height. Another characteristic of the 5th Gen is the back end would bounce often under load and even with tripple adjustable Eibach or Kw coilovers we never were able to dial this out. We worked with lots of aftermarket companies and it just was a inherent design of that rear IRS. My ZL1 was much more planted and GM changed a few things around by moving to a new rear housing which helped with the CV angles and the Mag shocks on the Zl1 were incredible. I got tired of breaking parts everytime i drove the car hard and now moved on. You gotta wonder why so many low mile 5th Gen that are modified are for sale any given time. Speak to the guys who race the 5th Gen in the Rolex series and they will confirm all the parts failures after each race.

this IRS stuff is cool but still nobody really has proved this to be better than the DSE Quadralink or other stuff on the market for our cars and still DSE cars seem always at the top of the list at every event. Until results are really proven id stick with a 4 link for now because the investment is serious do so one of these kits.

Thanks for the info. Were you running the Driveshaft shop axles & CV joints, or stock parts? If this rear had stock 5th gen stuff I'd not be doing it.

Staying with the tried and true is probably best for most people out there. We have done very well against the DSE cars but want to see if IRS can do any better. It has the potential to be a little better so we will find out soon & let you know.

Maybe more anti-squat would have helped the rear end bounce.

[David Pozzi]

Where do the shocks mount?

Shocks mount to the rear of the lower control arms, the top mounts to the frame rail.

[CTSV]

Thanks for the info. Were you running the Driveshaft shop axles & CV joints, or stock parts? If this rear had stock 5th gen stuff I'd not be doing it.

Staying with the tried and true is probably best for most people out there. We have done very well against the DSE cars but want to see if IRS can do any better. It has the potential to be a little better so we will find out soon & let you know.

Maybe more anti-squat would have helped the rear end bounce.


We broke factory parts and every part from the aftermarket, Frank at DSS became my buddy after all of this. We also dealt directly with Riley Tech who builds the Grand Am cars and even used some of their stuff but even they said its just a bad design from GM to fit that rear suspension and driveline under that Camaro body. Who knew but you gotta realize the Camaro was the GM bailout savior vehicle. Have you viewed alot of videos of heavily modified 5th gens online? Peter at Pedders also was very helpful as well,

I think GM and the aftermarket is better off to copy the CTSV platform because my CTSV is bulletproof and I kill the car daily and never broke a single part.


David Pozzi I thought I'd better insert an update here. Today is July 30, 2017. Mary has run the car extensively including a lot of Goodguys runs in first gear, SCCA National autocross Championship at Lincoln NE. Many Many regular autocrosses, some with me as co-driver. We have experienced NO failures at all which is GREAT! We did have some issue with the left inboard CV bolts backing off. It was probably due to my not being able to keep the CV joint grease from getting onto the threads during assembly and contaminating the loctite. I finally used Stage 8 bolts with lock tabs and not more troubles.

[andrewb70]

It would surprise me if AM just copied the 5th Gen Camaro geometry. Yes, the rear spindles are from the Camaro, but the Camaro rear track length is about 64" whereas the widest AM IRS is 60.5".

Another thing to consider is that the AM IRS is probably designed for a much lower ride height than the stock Camaro, so I can see where the axle shaft angle issue would not be a problem here. Ideally, the rear axles should point down slightly (or be level) from the diff to the spindles at ride height. This way, as the suspension goes through it's range of motion, both in bump and rebound, the axle angle doesn't vary much from straight. I ca see how on a heavily lowered 5th Gen Camaro the axles might actually point up towards the spindles at ride height. This would be detrimental when power is applied and the suspension is further compressed and the axle angle increases even more.

Hopefully AM took all this into account.

Andrew

[David Pozzi]

Morrison has it in their 69 Camaro, Mary & I drove it & we felt nothing like wheel hop that would cause damage. The axles looked pretty level when I looked under it but we will know more when we install ours. Every link is beefed up compared to a Camaro. It uses Camaro outer aluminum knuckles & a similar layout but not exactly the same. There is a separate adjuster for toe-steer, & another for toe-in.

[j-c-c]

I am surprised by the few comments that have disdain for inboard discs, with the reason being brake cooling?, seems to me anyone running hard enough to overheat their rear inboard discs would: 1. find a way to cool them, since it has been done 2. really appreciate the reduction in unsprung weight of inboard discs, especially if they made the effort to convert to IRS in the first place.

[David Pozzi]

The rear axle housing would need to have caliper mounts on it.
The rear axles would have stress reversal pressures.
Brake torque would not be reacted through the suspension links, meaning there would be reduced anti-squat.
There will be a lot of heat thrown off by the discs, right ahead of the fuel tank, you'd have to figure out how to cool them plus divert the heat away from the fuel tank.

Not insurmountable, but is enough gained to be worth it? It's not something I'm ready to take on right now.

[silver69camaro]

Hi Guys,
Thanks for the nice words about our new setup. I haven't been on here much lately, mostly because for the past 3 years I've been eyeballs deep in multilink research and design. I'm proud to finally see this design come to life, and to have it perform above and beyond my expectations was just icing on the cake.

There were a couple things I wanted to say, although David has covered many things.
1. The geometry is not from a 5th gen Camaro. While it uses 5th gen knuckles, that's it - that's where it stops. I studied multilink design for a couple years, and while the GM design is pretty good (despite some issues that stem from bean-counters), it could use lots of improvement.
2. We chose not to use a 9" for a couple reasons. First, Strange did an absolute fantastic job with their Dana 60 replacement diff, it's beautiful and robust. Best of all, it uses OEM gears for zero noise. Guys have taken the stock diff into the 9s, and this could go further. This unit is light, durable, quiet, and well designed.
3. While I like the CTS front platform, I wasn't a fan of the rear. It had some issues that I felt weren't appropriate for what we are aiming for. It's great for the CTS, but just not what I was looking for.
4. CTSV, about the line in the catalog about being influenced in other designs, it's absolutely true. Several years ago Craig and I went to a high end Porsche shop and saw a multilink rear suspension that could possibly fit under musclecars...and that's where it all started. Just about every (if not all) high end manufacturers use multilinks in back, and some of the geometry properties that make those cars special have been put into this suspension. It just so happened that GM had a knuckle that was the height I needed, the general layout I wanted, accepted a Corvette wheel hub, was reasonably affordable, and had great brake options. I couldn't have been happier! I was looking for a good year for a knuckle that would work right and I was starting to think it may never happen.
5. I agree that solid axles are great for most people, we and DSE have proven they can work well. We have always wanted to take it a step further, but until the multilink became available, there wasn't an IRS design out there I was happy with. Good IRS designs will introduce toe control, camber control, and reduced unsprung weight that a solid axle can't offer. And while this suspension really shines on the track, the streetability was even better. Ride quality is excellent, very much reduced NVH, and turn-in is better than I had originally hoped for. But again, solid axles can work well too.
6. The sway bar is a two-piece design as packaging is so tight a one piece bar wont fit. The couple we designed IMO is a work of art and took a couple weeks by itself in design time.
7. Like David said, the UCA is bent to allow for rail clearance. The rear crossmember is bent just to give the rear diff bracket something to weld to.
8. While this fits great in Camaros, we will offer it in just about every chassis we make. Some trunk designs are very accomodating for ours IRS, some are not. In any case, every car should be able to retain the factory rear seat.
9. This does not use 5th gen Camaro hubs. They are C6, which still has the standard 5x4.75 bolt pattern. This also allows for the upgrade for ZR1 hubs.
10. The coilovers attach to the vehicle's frame, not the cradle. This allow me to select the type of forces the cradle (and it's bushings) will experience to improve longitudinal and lateral stiffness without resorting to very expensive custom cradle isolators.

I think that's about it. I could go on and on about details but I simply don't have the time. Thanks guys.

[Cdog]

Hi Guys,
Thanks for the nice words about our new setup. I haven't been on here much lately, mostly because for the past 3 years I've been eyeballs deep in multilink research and design. I'm proud to finally see this design come to life, and to have it perform above and beyond my expectations was just icing on the cake.

There were a couple things I wanted to say, although David has covered many things.
1. The geometry is not from a 5th gen Camaro. While it uses 5th gen knuckles, that's it - that's where it stops. I studied multilink design for a couple years, and while the GM design is pretty good (despite some issues that stem from bean-counters), it could use lots of improvement.
2. We chose not to use a 9" for a couple reasons. First, Strange did an absolute fantastic job with their Dana 60 replacement diff, it's beautiful and robust. Best of all, it uses OEM gears for zero noise. Guys have taken the stock diff into the 9s, and this could go further. This unit is light, durable, quiet, and well designed.
3. While I like the CTS front platform, I wasn't a fan of the rear. It had some issues that I felt weren't appropriate for what we are aiming for. It's great for the CTS, but just not what I was looking for.
4. CTSV, about the line in the catalog about being influenced in other designs, it's absolutely true. Several years ago Craig and I went to a high end Porsche shop and saw a multilink rear suspension that could possibly fit under musclecars...and that's where it all started. Just about every (if not all) high end manufacturers use multilinks in back, and some of the geometry properties that make those cars special have been put into this suspension. It just so happened that GM had a knuckle that was the height I needed, the general layout I wanted, accepted a Corvette wheel hub, was reasonably affordable, and had great brake options. I couldn't have been happier! I was looking for a good year for a knuckle that would work right and I was starting to think it may never happen.
5. I agree that solid axles are great for most people, we and DSE have proven they can work well. We have always wanted to take it a step further, but until the multilink became available, there wasn't an IRS design out there I was happy with. Good IRS designs will introduce toe control, camber control, and reduced unsprung weight that a solid axle can't offer. And while this suspension really shines on the track, the streetability was even better. Ride quality is excellent, very much reduced NVH, and turn-in is better than I had originally hoped for. But again, solid axles can work well too.
6. The sway bar is a two-piece design as packaging is so tight a one piece bar wont fit. The couple we designed IMO is a work of art and took a couple weeks by itself in design time.
7. Like David said, the UCA is bent to allow for rail clearance. The rear crossmember is bent just to give the rear diff bracket something to weld to.
8. While this fits great in Camaros, we will offer it in just about every chassis we make. Some trunk designs are very accomodating for ours IRS, some are not. In any case, every car should be able to retain the factory rear seat.
9. This does not use 5th gen Camaro hubs. They are C6, which still has the standard 5x4.75 bolt pattern. This also allows for the upgrade for ZR1 hubs.
10. The coilovers attach to the vehicle's frame, not the cradle. This allow me to select the type of forces the cradle (and it's bushings) will experience to improve longitudinal and lateral stiffness without resorting to very expensive custom cradle isolators.

I think that's about it. I could go on and on about details but I simply don't have the time. Thanks guys.



Matt,

Great post. So we have installed the AM Tri-4 link in my 69 Camaro we are building to get back out there with the pack. Will this new IRS work with the AM frame portion of the tri-4 link? If so can you illustrate how it would install?

Thanks in advance.

[silver69camaro]

Matt,

Great post. So we have installed the AM Tri-4 link in my 69 Camaro we are building to get back out there with the pack. Will this new IRS work with the AM frame portion of the tri-4 link? If so can you illustrate how it would install?

Thanks in advance.

Yes it works great with your subframe and is the same setup we have in our Camaro. At a minimum, remove the forward LCA brackets and the rear cross tube (by the fuel tank). We elected to remove the sway bar and UCA frame brackets as well, just to make it clean. From there:
1. Mock up the IRS in the car with the frame brackets bolted on.
2. Center the wheel in the wheel arch, check for square.
3. Tack the frame brackets to the subframe.
4. Remove IRS then fully weld brackets.

On a first gen, there are two small sheetmetal areas that need to be cut - and thankfully they are small and easy to patch. I'll see if I can dig up some photos. The rear seat can stay as well as the stock fuel tank. If a person were to buy the rear subframe from us along with the IRS, all the bracket fitment will be done here at AME.

The cradle can be removed with just four bolts. It's very easy. If you're interested and need more info, PM me and we'll go from there.

[Cdog]

Yes it works great with your subframe and is the same setup we have in our Camaro. At a minimum, remove the forward LCA brackets and the rear cross tube (by the fuel tank). We elected to remove the sway bar and UCA frame brackets as well, just to make it clean. From there:
1. Mock up the IRS in the car with the frame brackets bolted on.
2. Center the wheel in the wheel arch, check for square.
3. Tack the frame brackets to the subframe.
4. Remove IRS then fully weld brackets.

On a first gen, there are two small sheetmetal areas that need to be cut - and thankfully they are small and easy to patch. I'll see if I can dig up some photos. The rear seat can stay as well as the stock fuel tank. If a person were to buy the rear subframe from us along with the IRS, all the bracket fitment will be done here at AME.

The cradle can be removed with just four bolts. It's very easy. If you're interested and need more info, PM me and we'll go from there.


Thanks for the info. We’re going to build the 69 with the tri-4 first then look at this as an evolution with the car. We had a meeting over last weekend discussing our build time frame. I brought the new AM catalog to show it off. Needless to say we’re big fans. We need more Art Morrison products over at Starlite Garage.

[andrewb70]

Matt,

Thanks for chiming in.

Can you elaborate more on things like camber and toe curves as well as the anti-squat characteristics?

Also, I would like to know how this system integrates with the A-body frames and the front suspension used on them.

Andrew

[silver69camaro]

Sure thing Andrew.

Camber gain is a consistant 0.520 degrees per inch of travel, antisquat is similar to our 3-link, about 40% but that changes pretty easily depending on the vehicle. Roll center movement is 1:1 with chassis height, and lateral migration is on par with our C6 front suspension.

The toe curve is a bit different than what you may be used to, and this may sound a bit silly, I'm not sure how many details I want to divulge as it is a bit of a trade secret. It will toe out and toe in by various amounts in order to steer the rear axle into a corner, but large amounts of bump travel (say a pothole or similar) will toe in about 0.017" for stability. The magnitude of the roll steer is adjustable by an eccentric on the cradle, and will be pre-set at a conservative amount here at AME. Careful tuners will really find this helpful as they can fine-tune handing woes caused by various factors (too much/little rear grip, too much/little power, very short/long wheelbases, extra tight autocross courses, etc). With street driving, as David had mentioned, the rear turn in is very sharp and may feel almost alarming at first but the amount of grip is amazing.

Because of the sensitivity of the cradle toe-link location, our lead shop man built a tool for the cradle that has astounding accuracy. After every component is welded, side-to-side pivot measurements are typically within .008" of each other - something that I wouldn't have thought was possible. It's quite amazing.

Moving on to the A-body, they will require a bit of sheetmetal work behind axle C/L, but nothing in the front. Fuel tank is fine, rear seat is fine. I can't say much about about the aftermarket front suspensions other than ours, as I don't have detailed data on critical metrics.

[andrewb70]

Matt,

I sent you a PM.

Andrew

[CTSV]

Ok i was really looking this over again today in the AM catalog i received and this question is for AM direct or its reps

it looks like this IRS rear cradle has 4 mounting locations with pressed in rubber bushings almost like a modern OEM type rear IRS subframe.

How does this work on a 69 Camaro? what is involved making this bolt in or is this welded in while replacing the rear OEM frame rails?

Also im just a bit confused are you making these IRS for various cars or just one system as shown in your catalog that must be retrofitted to any car? Will you be offering this IRS on your full chassis in place of the 4 links you currently offer?

i think it looks great i am just wondering what this will take to install in lets see a Mustang, Camaro, Chevelle or Corvette. Please fill in those details as I am in the process of building another car with IRS and i had my mind set on a Fast Track Chassis.

[silver69camaro]

When using our IRS, you have the option of purchasing our brackets (that weld to the stock frame) in which the IRS cradle bolts to, or you can purchase a subframe/full frame from us with those brackets already integrated. In terms of a Camaro, we've had our rear subframe available for a couple years that only requires the OEM frame rails to be removed. That same subframe can be outfitted with the cradle brackets (like our car has). While you could weld to the OEM rails, they are very thin and I don't recommend attaching much of anything to them. You could reinforce the rail, but by the time you are done, it would have been faster to install our subframe. So in short, every frame we currently offer (builder's platform or bolt on, sans trucks) will have the IRS available.

The amount of cutting required, if any, is determined by the OEM sheetmetal profile. No way around that. Some cars have more room than others. We have one cradle design that is extremely compact and will work very well in most cars, but it can't fit everything.

Does that answer your questions?

[HellPhish89]

..this is going to possibly be a pie in the sky/stupid question but... any plans to make it work (with a weld in bracket kit) in later generations of FBody? like say.. a third generation car?

[andrewb70]

..this is going to possibly be a pie in the sky/stupid question but... any plans to make it work (with a weld in bracket kit) in later generations of FBody? like say.. a third generation car?

The cradle looks easy enough to adapt to a wide range of chassis. I bet if you found a competent chassis shop in your area it wouldn't take them a lot of work to make the mounts for the cradle in any chassis.

Andrew

[silver69camaro]

..this is going to possibly be a pie in the sky/stupid question but... any plans to make it work (with a weld in bracket kit) in later generations of FBody? like say.. a third generation car?

The only thing we could do in that case would be to:
1. Draw up a weld-in clip complete with frame rails with cradle mounts already attached (we've done a few for those cars, but mostly drag 4-links)
2. Give you cradle brackets that you weld in to your factory unibody rails (provided they are in good shape and are of sufficient thickness)

[David Pozzi]

Nearly done with the install, I'll post some details once I'm finished. It's been way more cutting & welding than a first gen, but turned out pretty nice.
92234

Frame supports are 2" wide on each side of the flat panels. I put some bead rolls into them to stiffen them up.
92239

I raised the floor placing it on top of the new crossmember. The raised floor allows space for the mufflers, there is around 1/2" clearance. There is a factory kickup in the area of the crossmember, so the forward edge of the stock floor lays on top of it.

Below, you can see the edges of the old floor along the edges of the frame rails. I think it may have worked better to have placed the frame braces farther inward closer to the edge. It would look cleaner.
92241

Thermo Tec insulation added.
92240

I cut the corners off the trunk which gained a lot of access room to get at the subframe bolts and upper shock mounts.
I still need to cut holes for the shock reservoirs to pass through.
92238

[jtwoods4]

That is beautiful. Nice job.

[MrQuick]

Nice work David. So its a bolt in cradle? Can't wait to hear some feedback on the new set up.

[David Pozzi]

It goes in & out pretty easily with just 4 bolts.
We should have the car at Pleasanton Goodguys.

[Rod]

It goes in & out pretty easily with just 4 bolts.
We should have the car at Pleasanton Goodguys.

AWESOME!!! cant wait David see you there!!

[DJW32]

David,
Looks great!

Did you add any support to the stock frame rails?

[David Pozzi]

Yes, I plated inside the car on top of the frame rails with 10 ga cold rolled steel spaced 2" apart. I added support inside in the rear seat kick-up vertical area to compensate for cutting most of the rear frame rail away to clear the toe links. I also plated the remains of the frame rail kick-up in 10 ga steel.
David

[David Pozzi]

92457Baer made a kit to put 14" rotors & 6R calipers on the Camaro knuckles.
The rotor hat is like a Corvette, very shallow, so your wheel hub area needs to be made like Corvette wheels.

[chevelletiger]

david,is mary ditching the hotchkis 3 link and all the front set up...for sale?ha!ha!
phil

[Bowtie racing]

Thank you Matt for detaild information of this new irs. Much apreciated!

[David Pozzi]

The Hotchkis 3 link is going back to Hotchkis, they want to see how it's held up.
Did rear alignment yesterday, hope to drive it today! Old floor mats make great knee pads.


92655

[andrewb70]

Looking forward to some driving impressions.

Andrew

[Nicks67GTO]

I just went through this thread for the first time and maybe I missed it but I have to assume this is much heavier than a traditional leaf spring/ solid axle rear....right? How much more does it weigh than the standard rear chassis that would be removed? Now for road racing/auto x, would that be a negative because the overall weight was increased? Or maybe positive because the cars weight bias be more evenly balanced?

[andrewb70]

I just went through this thread for the first time and maybe I missed it but I have to assume this is much heavier than a traditional leaf spring/ solid axle rear....right? How much more does it weigh than the standard rear chassis that would be removed? Now for road racing/auto x, would that be a negative because the overall weight was increased? Or maybe positive because the cars weight bias be more evenly balanced?

The main thing to consider is not only the total weight as compared to a live axle, but also the unsprung weight. An IRS system generally offers a significant reduction in unsprung weight, which simultaneously improves handling AND ride quality. This system uses a Strange diff housing which is cast from aluminum. I bet the increase in total weight is less than 50 pounds compared against an all iron and steel 12 bolt or 9", and I bet it is even less if compared to an iron Dana 60 (which this diff is based on). And as you pointed out, the extra increase in weight in the rear might be a good thing for weight distribution. I bet Mary's Camaro now is pretty close to 50/50, and I am sure that David will post some corner weights eventually (hint..hint...).

The other benefit to this system is a significant reduction in pad knock back and greater safety.


Andrew

[andrewb70]

David,

Can you clarify brake fitment a little more. I know the rear spindle is Gen 5 f-body, so I assume any Gen 5 caliper will bolt up. But since the hub is ZR1 does that change the rotor offset or will Gen 5 f-body rotors work as well?

Andrew

[David Pozzi]

I think 5th gen brakes will work, but I don't have any to try. They won't clear 18" wheels. Actually, it remains to be seen if 18" wheels will clear stock Camaro brakes. The Baer 5th gen rear brakes in 15" would have had 1/8" clearance which we didn't want to chance. It depends on the wheel shape.

I did have to open up the Baer rotor center hole to fit the Corvette hub. I'll give them feedback on it. Maybe the Camaro pilot is smaller?

I drove the car today. Driving on a familiar very bumpy road, the ride quality is excellent! The ride is better than any other Camaro I've driven there. Going from leaf springs to 3 link was a step forward, this is a leap forward! I'm very glad I ordered one for my 67 Camaro.

I didn't get to slide around any corners yet, but the car is very responsive, it changes direction with much less steering input, like it had a faster ratio rack installed. I gassed it in first & got wheel spin but no hint of wheel hop. There is no gear whine, no vibrations, the car runs down the road very smoothly!

[andrewb70]

Dave,

Thanks for the update. One thing that I would be interested in is the front and rear operating angle of the u-joints.

Andrew

[David Pozzi]

The first test drive went awesome! Super smooth ride compared to the old stuff. No gear noise or vibrations, the steering feels faster with the rear end helping. The rear feels very responsive, it doesn't GO anywhere but it feels like it wants to change direction, kinda "free" feeling that takes some getting used to, kinda like rear tire pressure is low. I have the rear steer amount set pretty high right now.

The car is SO much more comfortable, & responds quickly to small inputs. I didn't get to corner it very hard, but it felt pretty good. I used to hate driving it on the street, but now it's a car I would enjoy touring in.

I'll add up the weights, but I think we gained 50 to 80 lbs, but it's in the rear and low. We gained nearly 1%!rear weight! lost 1% front weight.
I can't wait to get mine running, I picked it up today with new frame rails.
92795

[HellPhish89]

I think 5th gen brakes will work, but I don't have any to try. They won't clear 18" wheels. Actually, it remains to be seen if 18" wheels will clear stock Camaro brakes. The Baer 5th gen rear brakes in 15" would have had 1/8" clearance which we didn't want to chance. It depends on the wheel shape.

<snip>
18 should be fine, my C5 wheels clear. the 17" RT-S wheels will clear the camaro brembos safely as will the CTW's.

[silver69camaro]

David,

Can you clarify brake fitment a little more. I know the rear spindle is Gen 5 f-body, so I assume any Gen 5 caliper will bolt up. But since the hub is ZR1 does that change the rotor offset or will Gen 5 f-body rotors work as well?

Andrew

Brakes are fairly easy for this setup as, like you said, a 5th Gen knuckle is used. The C6/ZR1 hubs have a register diameter that is about .090" (or so) larger than the 5th Gen. My decision to use this hub was because of the wheel bolt pattern: Corvettes even to this day still use a 5x4.75 bolt pattern, while Gen 5 Camaros are 5x4.72. Rather than re-drill the bolt pattern, I'd rather have the rotor registers opened up slightly. I battled with this decision for a long time because each method has upsides and downsides. In the end, I ended up with this decision also because it lowered the overall cost to the customer by about $50 and gave the option of using a standard C6 hub, or the upgraded ZR1 hub which is so well proven.

[andrewb70]

Brakes are fairly easy for this setup as, like you said, a 5th Gen knuckle is used. The C6/ZR1 hubs have a register diameter that is about .090" (or so) larger than the 5th Gen. My decision to use this hub was because of the wheel bolt pattern: Corvettes even to this day still use a 5x4.75 bolt pattern, while Gen 5 Camaros are 5x4.72. Rather than re-drill the bolt pattern, I'd rather have the rotor registers opened up slightly. I battled with this decision for a long time because each method has upsides and downsides. In the end, I ended up with this decision also because it lowered the overall cost to the customer by about $50 and gave the option of using a standard C6 hub, or the upgraded ZR1 hub which is so well proven.

Matt,

Thank you for the clarification.

One thing that you guys want to consider is making some adapter brackets for C5/6 spindles in the front to accommodate Gen 5 Camaro breaks. If AM is going to offer this as an option for all of your chassis, I can see many customers opting to use the SS Brembo brakes that can be easily sources and seem to be well suited to heavy cars like A-bodies, considering Gen 5 Camaros are about the same weight. Food for thought.

Andrew

[silver69camaro]

I just went through this thread for the first time and maybe I missed it but I have to assume this is much heavier than a traditional leaf spring/ solid axle rear....right? How much more does it weigh than the standard rear chassis that would be removed? Now for road racing/auto x, would that be a negative because the overall weight was increased? Or maybe positive because the cars weight bias be more evenly balanced?

This is tough to answer because everybody has different axle weights. I had a 9" (iron center section, .188" tubes, 13" brakes, 3 link with watts) before, and this setup added about 50 lbs. Part of that was because now I have larger brakes (14.25") and I'm using the heavier Strange differential. You have the option of ordering this suspension with the OEM 5th Gen diff which is about 35lbs lighter. The advantage of adding a bit more rear weight (and it's down low) is usually a good thing for these cars. But like Andrew said the difference in unsprung weight is great, and you'll notice the difference immediately.

Anyway, on my first gen, it weighs 35xxlbs with 3/4" tank of fuel, 185lb driver, and a 50.7% front weight bias. I couldn't be much happier with that.

92806

[jtwoods4]

The first test drive went awesome! Super smooth ride compared to the old stuff. No gear noise or vibrations, the steering feels faster with the rear end helping. The rear feels very responsive, it doesn't GO anywhere but it feels like it wants to change direction, kinda "free" feeling that takes some getting used to, kinda like rear tire pressure is low. I have the rear steer amount set pretty high right now.

The car is SO much more comfortable, & responds quickly to small inputs. I didn't get to corner it very hard, but it felt pretty good. I used to hate driving it on the street, but now it's a car I would enjoy touring in.

I'll add up the weights, but I think we gained 50 to 80 lbs, but it's in the rear and low. We gained nearly 1%!rear weight! lost 1% front weight.
I can't wait to get mine running, I picked it up today with new frame rails.
92795


I am jealous

[silver69camaro]

Matt,

Thank you for the clarification.

One thing that you guys want to consider is making some adapter brackets for C5/6 spindles in the front to accommodate Gen 5 Camaro breaks. If AM is going to offer this as an option for all of your chassis, I can see many customers opting to use the SS Brembo brakes that can be easily sources and seem to be well suited to heavy cars like A-bodies, considering Gen 5 Camaros are about the same weight. Food for thought.

Andrew

That's a good idea. I'll check that out. I initially didn't want to offer the 5th Gen rear brakes because of the front mismatch, but a front adapter would solve that issue.

[andrewb70]

That's a good idea. I'll check that out. I initially didn't want to offer the 5th Gen rear brakes because of the front mismatch, but a front adapter would solve that issue.

Matt,

Can you also clarify the parking break components? I see in the pictures of David's rear for his first gen there is a drum brake arrangement. Does the OEM Gen 5 Camaro e-brake system work with the Corvette hubs?

Andrew

[silver69camaro]

Matt,

Can you also clarify the parking break components? I see in the pictures of David's rear for his first gen there is a drum brake arrangement. Does the OEM Gen 5 Camaro e-brake system work with the Corvette hubs?

Andrew

All the parking brake components are Gen 5 Camaro parts, off the shelf stuff. The C6/ZR1 hub is dimensionally identical to the Gen 5 Camaro, minus the register diameter. The e-brake is activated by a small lever pulled by a cable, much like the common Explorer type e-brake. We have a simple adapter that will allow Lokar cables to be used.

When an IRS is ordered from AME, it will be fully assembled when it leaves our shop - which includes the parking brake components.

[DJW32]

David,

The rear setup looks great! Can't wait to see a build thread.

[andrewb70]

All the parking brake components are Gen 5 Camaro parts, off the shelf stuff. The C6/ZR1 hub is dimensionally identical to the Gen 5 Camaro, minus the register diameter. The e-brake is activated by a small lever pulled by a cable, much like the common Explorer type e-brake. We have a simple adapter that will allow Lokar cables to be used.

When an IRS is ordered from AME, it will be fully assembled when it leaves our shop - which includes the parking brake components.

Thanks for the clarification!

Andrew

[carbuff]

Dave / Matt,

Perhaps I missed it earlier in the thread, but can either of you comment of exhaust routing? Did you go under, did either of you take pipes all the way to the rear of the car?

[David Pozzi]

Matt has full tail pipes. Ours kick down at the rear of the cradle.
92821

[David Pozzi]

Did two autocrosses this weekend. The IRS is working great! The car is faster than ever. The amount of rear steer was initially set too high but things are working well with it at a lower setting. Now it's set the same as what Morrison has been running all along.

S-nhjVa5V4M

Same video higher quality: http://m.youtube.com/watch?v=S-nhjVa5V4M

Suspension video
L6ozRyAr6Vs

Higher quality version: http://youtu.be/L6ozRyAr6Vs

[silver69camaro]

Dave / Matt,

Perhaps I missed it earlier in the thread, but can either of you comment of exhaust routing? Did you go under, did either of you take pipes all the way to the rear of the car?

You can go under like how David did (and then go up and out the rear, or terminate it at the diff), and we snaked it under the CV then routed beside the fuel tank.

92882

[David Pozzi]

I just went through this thread for the first time and maybe I missed it but I have to assume this is much heavier than a traditional leaf spring/ solid axle rear....right? How much more does it weigh than the standard rear chassis that would be removed? Now for road racing/auto x, would that be a negative because the overall weight was increased? Or maybe positive because the cars weight bias be more evenly balanced?

We gained 70 lbs.
Rear weight percent increased by 1% front weight decreased 1%

[carbuff]

Thanx Matt... Those look to be 2.5" pipes, is that correct? Is there room for 3" through there?

[DJW32]

The vids look good. For comparison sake, did maier show up at this auto-x? If so, what were his times?

[andrewb70]

The vids look good. For comparison sake, did maier show up at this auto-x? If so, what were his times?

What would that information tell you? A Mustang is smaller, lighter, different driver, possibly different tires, etc...Way too many other variables to account for.

Andrew

[silver69camaro]

Thanx Matt... Those look to be 2.5" pipes, is that correct? Is there room for 3" through there?

2.5". 3" could be done, but I'd route it under the diff like how David did. If a person were to order the cradle with the OEM 5th Gen diff, it allows much more room for larger exhaust. The Strange diff is large in comparison.

[andrewb70]

Matt,

What are the implications with regard to the axles when using different diffs (stock 5 Gen vs. ZL1, vs. Strange)?

Andrew

[CraigMorrison]

Thanks for asking great questions guys! Either Matt or myself will try to answer as quickly as possible. One thing that I haven't seen yet is any question regarding track width. We are offering four different track widths. 55.5", 57.5", 59.5" and 61.5". With the four different widths, we will definitely be able to set this IRS up for a lot of different applications. For out GT-Sport line of bolt-in chassis (C1, A-Body, 55-57, 49-54, 1st Gen rear sub) this will be an available option. We will also be able to do this on all of our custom chassis as well as sell the cradle with lose brackets. So far this has been the most popular with a lot of customers retrofitting this suspension into their existing chassis or reinforced OE subframes. While David did the install on Mary's car using the existing OE subframe, Matt has designed a great replacement rear sub for these cars. Any other questions, please let us know.

[silver69camaro]

Matt,

What are the implications with regard to the axles when using different diffs (stock 5 Gen vs. ZL1, vs. Strange)?

Andrew

The Strange diff is a drop-in replacement for a 5th Gen differential, so the axles are the same.

I haven't worked much with the ZL1 differential because the Strange unit is extremely durable, wider range of gear and diff choices, and much lighter. I do not see any advantage to using a ZL1 diff. The ZL1 does offer a diff cooler, but that can be easily added with our system as well.

[CraigMorrison]

The Strange diff is a drop-in replacement for a 5th Gen differential, so the axles are the same.

I haven't worked much with the ZL1 differential because the Strange unit is extremely durable, wider range of gear and diff choices, and much lighter. I do not see any advantage to using a ZL1 diff. The ZL1 does offer a diff cooler, but that can be easily added with our system as well.


And we did this on David's diff cover - added ports for the external pump and cooler.

[David Pozzi]

The vids look good. For comparison sake, did maier show up at this auto-x? If so, what were his times?

We tested at a different event closer to home & got in a lot more runs. Maier & Hobaugh were at Goodguys in Pleasanton.

I had some extra bungs put on the diff cover. Will monitor temps to see if a cooler is needed.

[andrewb70]

The Strange diff is a drop-in replacement for a 5th Gen differential, so the axles are the same.

I haven't worked much with the ZL1 differential because the Strange unit is extremely durable, wider range of gear and diff choices, and much lighter. I do not see any advantage to using a ZL1 diff. The ZL1 does offer a diff cooler, but that can be easily added with our system as well.

The only reason I am talking about the ZL1 rear diff is because the Strange can only go down to a 3.50 gear, while the ZL1 is offered in a 3.23.

Andrew

[DJW32]

What would that information tell you? A Mustang is smaller, lighter, different driver, possibly different tires, etc...Way too many other variables to account for.

Andrew

Simple. Mary and mike are very fast. If Mary, or David, would have beaten Mike by a good margin, I would say that the new rear is worth it's weight in gold.

[CraigMorrison]

The only reason I am talking about the ZL1 rear diff is because the Strange can only go down to a 3.50 gear, while the ZL1 is offered in a 3.23.

Andrew

Andrew, it should definitely fit, but keep in mind that we are building a new back cover for both the OE Camaro diffs and the Strange diff. The stock Camaro configuration has it's rear mount offset to one side. Because we are doing multiple track widths, we have centered that mount, if we hadn't we definitely wouldn't have been able to pull off the 55.5" option.

[dontlifttoshift]

What is the maximum wheel backspace with an 18" wheel?

Would it be safe to assume that the widest track width may offer the best suspension geometry?

[silver69camaro]

What is the maximum wheel backspace with an 18" wheel?

Would it be safe to assume that the widest track width may offer the best suspension geometry?

Yes, wider is typically always better. However, our multilink can get away with narrower track widths because the links provide direct load paths that efficiently transfer forces to the cradle. Because of this I'm comfortable suggesting a track width that is a couple inches narrower than what a typical IRS can allow - unless the person has an extremely powerful engine with sticky tires.

18" wheels, assuming the hoops are spun aluminum, will allow a backspace of 7.5".

[andrewb70]

Yes, wider is typically always better. However, our multilink can get away with narrower track widths because the links provide direct load paths that efficiently transfer forces to the cradle. Because of this I'm comfortable suggesting a track width that is a couple inches narrower than what a typical IRS can allow - unless the person has an extremely powerful engine with sticky tires.

18" wheels, assuming the hoops are spun aluminum, will allow a backspace of 7.5".

So Matt, ideally, on a GM A-body would you run the 61.5" rear with the biggest offset wheel possible?

Andrew

[silver69camaro]

So Matt, ideally, on a GM A-body would you run the 61.5" rear with the biggest offset wheel possible?

Andrew

For ideal geometry, yes. But for this suspension a 59.5" would work great too.

[andrewb70]

For ideal geometry, yes. But for this suspension a 59.5" would work great too.

I guess using a slightly narrower rear will allow the wheel to have more of an outer lip which tends to look better on older cars.

Andrew

[CraigMorrison]

I guess using a slightly narrower rear will allow the wheel to have more of an outer lip which tends to look better on older cars.

Andrew

Exactly!

[PPG TRIGGER MAN]

Well I've been reading this thread with interest because I recently bought an entire ZL1 rear setup. I looked at the AM piece, and it is awesome, but the price was more than the budget would allow. I was hoping someone else had taken the ZL1 rear and utilized it already so I could get some feedback. I got the whole setup with 14" brembos for less than 4k so it was too tempting to pass up. The other thing is i'm using it in a big car that will see more street time than anything else. The car is a 62 Buick Lesabre. for the front i'm using mustang II from Hiedt. I'm going to build the rear rails higher in the car so hopefully I can get the stance low while maintaining good geometry on the cv's. Here is a couple pics of the unit.9323193232 93233

[David Pozzi]

Simple. Mary and mike are very fast. If Mary, or David, would have beaten Mike by a good margin, I would say that the new rear is worth it's weight in gold.

In general, this makes sense. One issue though is Mike, like us, is always improving his car so what beats what today may not hold up next weekend. At Del Mar last year, Mary beat Mike by .003 seconds, so any improvement by him could possibly put him ahead, but she won't be competing against 2013 Mike, with the old lower HP engine, it will be 2014 Mike with the Roush engine back in the car. BUT! She now has the IRS! :-)

[andrewb70]

There are several reasons why I am even discussing the ZL1 rear. First is cost, and probably least important is cost. A new ZL1 diff can be had for under $2000. Secondly, in my instance, I really want to run a gear ratio less than 3.54. The auto ZL1 gear is 3.23. Lastly, I want to use a CV joint at the rear and The Driveshft Shop make a simple adapter that bolts to the ZL1 3 finger flange that will accept a CV joint.

I am eager to see how Mary does this year as she learns to drive with the new rear and it gets tuned.

Andrew

[silver69camaro]

There are several reasons why I am even discussing the ZL1 rear. First is cost, and probably least important is cost. A new ZL1 diff can be had for under $2000. Secondly, in my instance, I really want to run a gear ratio less than 3.54. The auto ZL1 gear is 3.23. Lastly, I want to use a CV joint at the rear and The Driveshft Shop make a simple adapter that bolts to the ZL1 3 finger flange that will accept a CV joint.

I am eager to see how Mary does this year as she learns to drive with the new rear and it gets tuned.

Andrew

Andrew, why not look at the aluminum diffs? They'll save lots of weight, and notice on the Z/28 they switched from the iron ZL1 diff to the aluminum case again. Granted the Z/28 used a different gear, but we do offer the smaller aluminum diff in 3.23. If the OEM diff saves about 30lbs over the Strange aluminum diff, I'm sure it's 50+ over the ZL1. The OEM diff is pretty durable, and if you're road racing, add a fluid pump (it would be easy to do).

Just a thought.

[andrewb70]

Andrew, why not look at the aluminum diffs? They'll save lots of weight, and notice on the Z/28 they switched from the iron ZL1 diff to the aluminum case again. Granted the Z/28 used a different gear, but we do offer the smaller aluminum diff in 3.23. If the OEM diff saves about 30lbs over the Strange aluminum diff, I'm sure it's 50+ over the ZL1. The OEM diff is pretty durable, and if you're road racing, add a fluid pump (it would be easy to do).

Just a thought.

Good thought Matt. I am concerned about durability. Is the ring gear size the same on the aluminum diffs as it is on the ZL1? I thought the ZL1 had a bigger ring gear.

Andrew

[silver69camaro]

Good thought Matt. I am concerned about durability. Is the ring gear size the same on the aluminum diffs as it is on the ZL1? I thought the ZL1 had a bigger ring gear.

Andrew

The ZL1 is quite a bit larger, yes. The standard diff is 8.6", the ZL1 is about 9.9". Best I can tell, the Z/28 uses the smaller diff. I have a couple sources that I can ask, that info doesn't really seem available yet.

[keithq69]

I'm not sure if the Z28 is going to use the 8.6" aluminum section or an aluminum version of the ZL1 differential.
I have been trying to find out too but can't find any information.
The ZL1 has a built in cooler in the housing and the Z28 is going to have a cooler also so I'm thinking it may be a new housing.
Would love to know the specs if anyone had an inside track.

Keith.

[andrewb70]

I'm not sure if the Z28 is going to use the 8.6" aluminum section or an aluminum version of the ZL1 differential.
I have been trying to find out too but can't find any information.
The ZL1 has a built in cooler in the housing and the Z28 is going to have a cooler also so I'm thinking it may be a new housing.
Would love to know the specs if anyone had an inside track.

Keith.

Keith,

One way to tell would be if the part numbers for same ratio ring and pinion gears are the same between the ZL1 and the Z/28. The manual ZL1 gets a 3.73 gear as does the Z/28, however, it doesn't look like the R&P area serviceable items. I did a little looking around and it looks the the rear end assembly is sold complete.

Ultimately, I am just splitting hairs here. For the vast majority of power train combinations a 3.54 or numerically higher gear ratio is perfectly suitable. In which cace, the use of the S60 rear is ideal because it is both lighter and probably stronger than even the ZL1 rear end. It is just that for what I have envisioned (for my particular combination), I need huge torque capacity and something like a 3.08 or 3.23 gear.

Also, cudos to AM for using the gen 5 Camaro rear knuckle assembly. If it ever needs to be replaced it looks like the cost is less than $140 each!

Andrew

[keithq69]

I think the Z28 might use a 3.91 gear like the 1LE car does.
There are no part numbers or information available yet for the Z28.

[CraigMorrison]

Also, cudos to AM for using the gen 5 Camaro rear knuckle assembly. If it ever needs to be replaced it looks like the cost is less than $140 each!

Andrew

Thanks Andrew, but the thing that's really great about this part is that it's so darn compact. With the top to bottom height being relatively short it lends itself to be packaged into a lot of applications where extra fab work is at a minimum.

[silver69camaro]

I'm not sure if the Z28 is going to use the 8.6" aluminum section or an aluminum version of the ZL1 differential.
I have been trying to find out too but can't find any information.
The ZL1 has a built in cooler in the housing and the Z28 is going to have a cooler also so I'm thinking it may be a new housing.
Would love to know the specs if anyone had an inside track.

Keith.

My sources say the ring gear is the small diameter, and the housing is "similar if not the same" to the current production SS aluminum housing. The Torsen diff is a big plus, it is well tuned. A cooler would be easy to add to any housing.

[andrewb70]

Matt,

Do you have any insight as to how this set-up might work in a drag racing scenario? I realize that an IRS is far from ideal for drag racing (I am familiar with some challenges having owned a second gen RX7 and trying to drag race it), but how do you suppose it might work?

Andrew

[silver69camaro]

Andrew,
To be perfectly honest it's tough to say without trying it in a real high HP with sticky tires. One thing I can say is, it should work better than a Gen 5 Camaro does. Geometry is different, and the bushings are much much stiffer. I suspect it will do well, obviously not like a true 4-link however. I'm not concerned about strength, as the load paths are very efficient and axles are extremely strong.

[andrewb70]

Andrew,
To be perfectly honest it's tough to say without trying it in a real high HP with sticky tires. One thing I can say is, it should work better than a Gen 5 Camaro does. Geometry is different, and the bushings are much much stiffer. I suspect it will do well, obviously not like a true 4-link however. I'm not concerned about strength, as the load paths are very efficient and axles are extremely strong.

I am not concerted about strength either. As long as the diff is stout, I am confident in Frank's axles. I have worked with him before on custom axles for my RX7. I had a Ford 8.8 Cobra IRS in it and Frank broached my RX7 hubs for one of his massive outer CVs. It was extremely durable.

The RX7 used a swing arm style IRS and from what I understand had zero anti-squat. In order to fight the tendency to lift the rear tires, most second ten RX7 racers, including myself, ran stiff rear springs and shocks.

Does this set-up have some anti-squat built in? I realize that anti-squat/squat is a balancing game, but some is desirable even for road racing.

I am not looking for 1.2x second 60 foot times, but being able to get in the 1.6-1.8 would suit my needs.

Andrew

[silver69camaro]

Andrew, you're right, some is desirable in road racing. Since this was designed more for road racing it doesn't have too much anti-squat. I know some people get real fixated on anti without realizing that the minute you start applying throttle in a corner, the suspension is starting to bind - and that's bad. Compliance is good, bind is not. This suspension has 35% anti-squat, which is a touch less than our triangulated 4-bar. I'd rather have a guy get more forward traction hydraulically (via shocks) than to make the car lose grip when under power.

[andrewb70]

Andrew, you're right, some is desirable in road racing. Since this was designed more for road racing it doesn't have too much anti-squat. I know some people get real fixated on anti without realizing that the minute you start applying throttle in a corner, the suspension is starting to bind - and that's bad. Compliance is good, bind is not. This suspension has 35% anti-squat, which is a touch less than our triangulated 4-bar. I'd rather have a guy get more forward traction hydraulically (via shocks) than to make the car lose grip when under power.

Thanks Matt. You always give great answers, which I really appreciate.

Have you seen how they dial extra anti-squat on the Koenigsegg Agera R? They call it Triplex suspension.

Here is a great video that goes over some details:

https://www.youtube.com/watch?v=bbgjRBT4ltM&list=PLHa6PXrV-yIgnXSYFT07BouKhEhyFuWnf

I'd love to hear your thoughts on that. I think something like that can be made by using a bell crank arrangement in the trunk.

Andrew

[David Pozzi]

My thought is, you don't have engine torque reacting on the suspension links, so you can possibly use more anti squat on an IRS than a stick axle car.
Indy cars use a third shock acting on the anti-roll bar middle that does what the Konigsegg system does. It separates ride spring/shock from roll or one wheel bumps. In the case if a ground effects Indy car, maintaining ride height is critical.

[silver69camaro]

That's a good point David. You know it's funny reading about anti's in suspension books, most apply the same principles from a solid axle to an IRS. Most don't suggest that, like you say, the links do not have any reaction to engine torque, and the antisquat line is drawn from axle center instead of at the contact patch. Or the antisquat more of a reaction from forward thrust. Being a guy who has done solid axles for years, it took a while for me to see that.

When I designed this (and there was countless iterations, gives me a headache just thinking about that), what I came up with was what I feel is the best of all the iterations I had done. I landed at 35% anti-squat and 50% anti-dive with the anti-dive being the primary driver. Most agree that anti's result in some bind (some even run zero of each), and many had warned me that the power of todays LS engines can make anti-squat very sensitive and lead to erratic lateral grip when on the throttle. Multilinks allow the decoupling of both antis to some degree, but one still effects the other in small ways.

[silver69camaro]

Thanks Matt. You always give great answers, which I really appreciate.

Have you seen how they dial extra anti-squat on the Koenigsegg Agera R? They call it Triplex suspension.

Here is a great video that goes over some details:

https://www.youtube.com/watch?v=bbgjRBT4ltM&list=PLHa6PXrV-yIgnXSYFT07BouKhEhyFuWnf

I'd love to hear your thoughts on that. I think something like that can be made by using a bell crank arrangement in the trunk.

Andrew

Pretty well thought out stuff (obviously). I would think that would be a tuning nightmare! I would wonder if there was a easier method of packaging, probably not. Those are the types of cars where packaging constraints aren't a big deal, which is totally different than our industry.

[CraigMorrison]

Ok, so going back through this thread, the one thing I wanted to address is the pricing. When Super Chevy did the story on Matt's car, it was in the advanced prototype stage and we had no clue as to what the price was going to be, so with a best guess I put a number together. Please keep in mind that that also included the entire rear weld-in subframe for a 1st Gen car as well.

So, for what we have available now here is the pricing and component breakdown:
IRS Cradle
Strange S60 differential
Upper control arms
Front lower control arms (with Johnny Joints)
Rear lower control arms (with Johnny Joints)
Toe link kit
5th Gen Camaro knuckles machined to accept C6 hubs
C6 30-spline hubs
5th Gen Camaro parking brake kit
Two-piece adjustable sway bar
Cradle bushing kit
Driveshaft Shop 30 spline axle package w/ 930 CV joints
JRI non-adjustable monotube coil-overs
5th gen Camaro disc brake kit 12.4" rotor

This package (which is rated at 1400+ RWHP) is priced at $11,500
This IRS package can be added to any rear subframe or chassis in our line-up. We also have sold a number of these packages with loose brackets so customers can graft it into existing chassis and subframes. There are also numerous options available on the shocks and brakes.


The two biggest pricing factors in this IRS is the Strange S60 center and high HP Driveshaft Shop axles with the 930 CV's. We are going to be offering a package very shortly with a few different options for OE Camaro diffs as well as a more affordable axle package from Driveshaft Shop - power rating should still be in the 700-800 RWHP range.

Hope this answered a few questions regarding the pricing... Any more please let me know.

[carbuff]

Thanx for that information Craig. I'm curious about one thing. Why the non-adjustable JRi in the package you describe? As it sounds like the rest of the package is more on the higher end of the components, I was a little surprised by that.

While I'm typing... Do you have any approximation as to the price for the rear subframe which would work to package this setup in the rear of a second-gen F-body?

[David Pozzi]

They are pretty flexible in coming up with a suspension package that suits you. That's one of the reasons Mary, James, & I all bought front subframes from them.
I'm sure if you wanted an upgraded component, it's just an add-on.

[CraigMorrison]

Thanx for that information Craig. I'm curious about one thing. Why the non-adjustable JRi in the package you describe? As it sounds like the rest of the package is more on the higher end of the components, I was a little surprised by that.

While I'm typing... Do you have any approximation as to the price for the rear subframe which would work to package this setup in the rear of a second-gen F-body?

Bryan, please keep in mind that this is the starting point. I have non-adjustable JRI shocks on my truck and love them. We have guys that don't want to have to worry about messing with their shocks an we have guys that are very serious about shock tuning. JRI has non, single, double, triple and quadruple shocks and we can include any option that would best suit your particular application.

We do have a rear subframe available for 2nd gen cars. Matt Faro'ed the rails on the Camaro we have here and designed a sub that would fit as best as possible. 2nd gen cars are a real challenge out back with the rails being so tight to the axle housing. I'll check with sales and let you know a price.

[Nothingface5384]

i'm really liking their hydraulic J Ride shock system they offer

[CraigMorrison]

They have some pretty amazing offerings available.

[keithq69]

Regarding the Z28 differential housing.
I finally got a hold of a VIN number but when I checked with GM parts there are none listed yet.
You can only order for specific card with warranty issues.

[CraigMorrison]

We are still waiting to hear back from our sources as well.

[keithq69]

I live an hour and a half from where they build the Camaro. I'm tempted to go over there and see if I can dig anything up, haven't bothered though because I doubt anything will come of it.

[andrewb70]

I live an hour and a half from where they build the Camaro. I'm tempted to go over there and see if I can dig anything up, haven't bothered though because I doubt anything will come of it.

No point in doing that. You probably won't even be able to get inside the plant...LOL

Besides, it's not like the factory people know.

I bet Mark Steilow knows. Craig, surely you know him or know someone that knows him?

Andrew

[keithq69]

I agree Andrew, that's why I didn't bother trying LOL.
I tried contacting Mark, I'm sure he gets too many messages from people he doesn't know.
It seems like a part number would do me no good anyway, the parts aren't available yet.
I would like to know if I should wait for it or just get the 1LE diff and upgrade to the Z28 when it's available.
On a side note, a friend of mine Brian Makse was in New York today driving the new Z28 for an article he's writing. He loved it, seems like Chevrolet knocked it out of the park with this one.

[CraigMorrison]

No point in doing that. You probably won't even be able to get inside the plant...LOL

Besides, it's not like the factory people know.

I bet Mark Steilow knows. Craig, surely you know him or know someone that knows him?

Andrew

I do have all of Mark's contact info, but what Mark can get doesn't mean we will be able to buy it for our customers. We have a great relationship with handful of pretty large GM dealers - as soon as I get word of "yay" or "nay" I will let you guys know.

[silver69camaro]

Regarding the Z28 differential housing.
I finally got a hold of a VIN number but when I checked with GM parts there are none listed yet.
You can only order for specific card with warranty issues.

I have the numbers (although I'm sworn to secrecy) but they aren't listed as service numbers yet. Might be a while.

[CraigMorrison]

OK, so we finally have pricing on a more budget friendly IRS package:

So, this package includes the GM diff and GM axles and GM brakes, here is the pricing and component breakdown:
IRS Cradle
GM 5th Gen differential 3.27 gear ratio
Upper control arms
Front lower control arms (with Johnny Joints)
Rear lower control arms (with Johnny Joints)
Toe link kit
5th Gen Camaro knuckles machined to accept C6 hubs
C6 30-spline hubs
5th Gen Camaro parking brake kit
Two-piece adjustable sway bar
Cradle bushing kit
GM 5th gen axle package narrowed by The Driveshaft Shop
JRI non-adjustable monotube coil-overs
5th gen Camaro disc brake kit 12.4" rotor

This package will sell for $9865.00. We also have a 3.45 GM differential and a 3.91 GM differential also available.

[HellPhish89]

GM will not be allowing the sale of the Z28 diff and other parts without a proper vin code. sorry guys:
http://gmauthority.com/blog/2014/04/gm-makes-it-difficult-to-clone-2014-camaro-z28-by-restricting-these-35-parts/

[andrewb70]

GM will not be allowing the sale of the Z28 diff and other parts without a proper vin code. sorry guys:
http://gmauthority.com/blog/2014/04/gm-makes-it-difficult-to-clone-2014-camaro-z28-by-restricting-these-35-parts/

That's the most ridiculous thing I have ever heard. This isn't 1967 when cars went out the door and VIN numbers were forgotten. Presumably, every new Z/28 will be easily spotted by the VIN number which is in about a million places on new cars. This sounds like GM BS for keeping the price of those parts high...God forbid a Camaro owner buys a few parts to make a Z/28 clone...THE HORROR!!! Not that anyone would do that because it would be cheaper to just buy a real Z/28...

Andrew

[CraigMorrison]

GM will not be allowing the sale of the Z28 diff and other parts without a proper vin code. sorry guys:
http://gmauthority.com/blog/2014/04/gm-makes-it-difficult-to-clone-2014-camaro-z28-by-restricting-these-35-parts/

We saw this as well. That diff would have been fun to use. Who knows if this ban will stay in place. With the Strange S60 and the 3 different gear ratio differentials from the other Camaro's, we can't complain too much.

[HellPhish89]

im sure some conversation with torsen would get you what you want..

[DJW32]

David,
Do you think the car would benefit from a larger tire(width) in the front?

[BonzoHansen]

That's the most ridiculous thing I have ever heard. This isn't 1967 when cars went out the door and VIN numbers were forgotten. Presumably, every new Z/28 will be easily spotted by the VIN number which is in about a million places on new cars. This sounds like GM BS for keeping the price of those parts high...God forbid a Camaro owner buys a few parts to make a Z/28 clone...THE HORROR!!! Not that anyone would do that because it would be cheaper to just buy a real Z/28...

Andrewi think it is much more about inventory control

[David Pozzi]

David,
Do you think the car would benefit from a larger tire(width) in the front?

We now have 315 x 18's front & rear. For autocross, it's ideal to have equal size front & rear.

[CraigMorrison]

David,
Do you think the car would benefit from a larger tire(width) in the front?
With as hard as our IRS plants the tire, I would definitely be conservative on a rear tire choice in regards to width.

[CraigMorrison]

Looks like the Z/28 diff and cooler will be available after all! http://www.camaroperformers.com/news/2014-camaro-z28-parts-not-on-the-restricted-list/?sm_id=social23261764

[keithq69]

It will be available eventually but it's still restricted as of now.

[dhutton]

OK, so we finally have pricing on a more budget friendly IRS package:

So, this package includes the GM diff and GM axles and GM brakes, here is the pricing and component breakdown:
IRS Cradle
GM 5th Gen differential 3.27 gear ratio
Upper control arms
Front lower control arms (with Johnny Joints)
Rear lower control arms (with Johnny Joints)
Toe link kit
5th Gen Camaro knuckles machined to accept C6 hubs
C6 30-spline hubs
5th Gen Camaro parking brake kit
Two-piece adjustable sway bar
Cradle bushing kit
GM 5th gen axle package narrowed by The Driveshaft Shop
JRI non-adjustable monotube coil-overs
5th gen Camaro disc brake kit 12.4" rotor

This package will sell for $9865.00. We also have a 3.45 GM differential and a 3.91 GM differential also available.

Hi Craig. I assume this does not include the subframe to mount the suspension in a first gen Camaro. How much additional is that?

Thanks,
Don

[David Pozzi]

Here is a video of the Morrison IRS by Super Chevy Magazine, the story should appear in the January issue.

http://youtu.be/pp3LaDz_8Dg

[MCMLXIX]

Bringing this back up. I see there is a new Compact IRS being offered.
Are there any details that can be shared as to the differences between the two?
What are the dimensions of the mounting points?
Lastly, are there any options for an air ride setup?

https://static1.pt-content.com/images/pt/2016/08/pg6compactirs-1.jpg

[andrewb70]

Bringing this back up. I see there is a new Compact IRS being offered.
Are there any details that can be shared as to the differences between the two?
What are the dimensions of the mounting points?
Lastly, are there any options for an air ride setup?

https://static1.pt-content.com/images/pt/2016/08/pg6compactirs-1.jpg

Is that on the AM website somewhere?

Andrew

[dhutton]

Is that on the AM website somewhere?

Andrew

http://www.artmorrison.com/compactirs.php

Looks pretty good.

Don

[HellPhish89]

http://www.artmorrison.com/compactirs.php

Looks pretty good.

Don
it does. looks like it would be easier to convert the third gen fbodies with those.

[grendel]

Still wondering if I can use some of the IRS I already have, like a center section, spindles/hubs and my brakes... I'd love to get rid of the Mock set up in the rear. It works well, just a very bad taste.

[silver69camaro]

Hi guys,
I haven't been able to spend as much time on here as I would like - just too busy these days. It was brought to my attention that some info was needed on the IRS cradles we have to offer. To make sure everybody is on the same page, we have three cradles available. The full size cradle was the first design and fits 1st gens, 55-57s, etc. This cradle fits either the Strange Dana 60 diff or the 5th gen diff:

130851130852130853

[silver69camaro]

The compact unit is just that - compact. This design only fits the 5th gen diff but changes may come in the future to allow the Dana 60...although it would be a crazy tight fit. As you can see with the dimensions below it is both shorter vertically and front-to-back. Here's some dimensions on those:
130854130855130856

To make use of the reduction in vertical height, this cradle requires a different upper control arm. This design isn't as stiff as the full size cradle but is more than adequate for high performance applications.

[silver69camaro]

Lastly, we have a modified version of the full size cradle as seen in the image below. The full size on the left, compact on the right, and modified-full in the middle. We developed this for C2 Corvettes requiring the Dana 60.

130857

I'm not too familiar with 3rd gen floors but I do know they are tight. I think the compact would work pretty well...the 2nd gens, however, are difficult. The compact is a no-brainer for those but I'm pretty sure some floor cutting is needed behind the rear seat.

[andrewb70]

Matt,

Thanks for the detailed dimensional sheets!

Have you seen any of these used with a stock A-body frame? Any suggestions there?

Andrew

[MCMLXIX]

This was the data I was looking for... (and should be on the AME website)