New Art Morrison IRS

[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=bbgj...7BouKhEhyFuWnf

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=bbgj...7BouKhEhyFuWnf

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.