Modified A body Chassis

[clu269]

Looking for photos and or post of modified and narrowed rear frame rails. Its been a long time and ready to jump back in full bore chassis needs to be completed first. I want to run a 3 link in rear with 335/20 tires.

[raustinss]

Not sure why you want to change from the 4 link to a theee link . If you go to abcperformance.net and google mini tub pics theres a few YouTube videos too.

[clu269]

thanks for info. I will check out the mini tub. I am reworking the entire rear end and narrowing the frame rails.

[raustinss]

ABC performance aka Tony(s) kit you will be able to fit those tires easily and they sell wider wheel wells also . Tony's kit thou is based off the original 4 link design. As are most suspension companies who make parts for the 68-72 A bodies . The triangulated 4 link design is a very good set up.the frame needs some bracing and the suspension needs to be tightened up . Good luck

[jetmech442]

I didn't modify my frame for narrowing, but I did modify it for the 3 link. I only protruded into the back seat by about 1.5''. If I could do it again, I would have gone more and built a backseat armrest around the top mount point. I'm better in SVA length than original, but a longer top arm would be better. As it is right now though, my rear has a lot less vertical travel than original so maybe its not a big deal.

I added an adjustable bracket to the lower frame side arms so I could set them level at ride height.

[clu269]

HPI frame kit with new cross tube in place of the lower rear control arm brackets. The new rear frame rails will have the rear lower control arms mounted inside. The upper link I plan on mounting off the new cross brace.
Any thought?

[raustinss]

Dont buy the hpi kit ... they're a nightmare to deal with , I asked for a modified kit from them . The said yes np . We will have in x time . Well I held off my summer holidays so I could install it , nope nothing... then fall ... then xmas ... then I got nasty . Excuses from we're on holidays , there was a mix up , 3 times given fake shipping numbers , was told kit made it to toronto then the box was damaged and got sent back , .... it was only when I threatened to involved the R.C.M.P and have them charged with fraud and theft did they magically have my one off frame brace kit at my door 2 days later . It's a fantastic product but I wouldnt buy it from them directly, try going thru summit . Now onto the suspension why completely reinvent the wheel . I'm curious what you plans are for the car that would make the 3 link better than an improved 4 link ? Reason I ask is Tony from abc performance used to work for gm in engineering, probably has the fastest pro touring chevelle in the country. Mark from SC & C is a suspension guru still suggests a 4 link . Etc etc .

[clu269]

Only reason is I was told better for track car. I purchased the HPI kit modified for my needs of modified frame. I am glad I didn't have the issues you had. I have AFX spindles with SPC uppers and lowers, baer 6 piston front brakes, C6 rear brakes and speedtech chicane conversion with ridetech all 4 corners. Motor currently 470 CI Buick, T56 Moser 12 bolt. Build a 6.2 with LSA blower. Retirement toy.
I started 11 years ago and life got in the way. Back at it since last child graduates his year. I will call Tony on the mini tube and how his triangulates 4 link is setup. I did by all of my part with the exception on the chicane kit and coil-overs from Mark.

Thanks for your help.

[raustinss]

Nice , I have heard a 3 link can be better for some forms of racing but I dont know enough about the details of why. This was why I was asking , why change what already works and works very well . Like to see how this all works out .

[BMR Sales]

I had a build Thread that was F'd Up by Photobucket. Here are some Pictures. BTW, we will be coming out with a Frame Rail Kit soon!

https://i.hmjimg.com/images/2020/04/07/100_6529.jpg (https://www.hostmyjunk.com/image/VZsBZ)

https://i.hmjimg.com/images/2020/04/07/100_6533.jpg (https://www.hostmyjunk.com/image/VZU9d)

https://i.hmjimg.com/images/2020/04/07/100_6584.jpg (https://www.hostmyjunk.com/image/VZCPo)

https://i.hmjimg.com/images/2020/04/07/100_6607.jpg (https://www.hostmyjunk.com/image/VZqNi)

[Alwhite00]

Do you need a panhard bar with the 3 link?

[Cheveezy]

I had a build Thread that was F'd Up by Photobucket. Here are some Pictures. BTW, we will be coming out with a Frame Rail Kit soon!

https://i.hmjimg.com/images/2020/04/07/100_6529.jpg (https://www.hostmyjunk.com/image/VZsBZ)

https://i.hmjimg.com/images/2020/04/07/100_6533.jpg (https://www.hostmyjunk.com/image/VZU9d)

https://i.hmjimg.com/images/2020/04/07/100_6584.jpg (https://www.hostmyjunk.com/image/VZCPo)

https://i.hmjimg.com/images/2020/04/07/100_6607.jpg (https://www.hostmyjunk.com/image/VZqNi)

Did this require any other modifications?

[raustinss]

Probably new inner wheel wells otherwise kind of a useless modification lol

[BMR Sales]

Did this require any other modifications?

This car was the Rustiest PoS I've ever seen, so everything was done. When we come out with our Frame Rail Kits for the A-Bodies & G-Bodies, we will also be introducing a Rear Upper Shock/Strut Brace

[Cheveezy]

Probably new inner wheel wells otherwise kind of a useless modification lol

To clarify, any other SUSPENSION modifications required? Of course you'll need bigger tubs.

[raustinss]

To clarify, any other SUSPENSION modifications required? Of course you'll need bigger tubs.

Sorry this virus thing has my smart ass scale on 11 lol cheers , let us know how things work out for yourself

[clu269]

yes I will

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Do you need a panhard bar with the 3 link?

Yes do you have one available

[clu269]

I had a build Thread that was F'd Up by Photobucket. Here are some Pictures. BTW, we will be coming out with a Frame Rail Kit soon!

https://i.hmjimg.com/images/2020/04/07/100_6529.jpg (https://www.hostmyjunk.com/image/VZsBZ)

https://i.hmjimg.com/images/2020/04/07/100_6533.jpg (https://www.hostmyjunk.com/image/VZU9d)

https://i.hmjimg.com/images/2020/04/07/100_6584.jpg (https://www.hostmyjunk.com/image/VZCPo)

https://i.hmjimg.com/images/2020/04/07/100_6607.jpg (https://www.hostmyjunk.com/image/VZqNi)


Will it completely replace the rear frame rails or modify like the photos?

[BMR Sales]

Will it completely replace the rear frame rails or modify like the photos?

Modify like the pictures!

[CSC Design]

Here is a customer car we are working on currently.

[clu269]

Here is a customer car we are working on currently.

Where are you located?

[Nothingface5384]

3 link is better at everything compared to a 4 link Eve. With all spherical ends..
With except of 4 link being stronger for drag

For best overall rear suspension torque arm hands down 3 link of still rated over tri 4
More Road race 3 link
More drag tri 4link

[clu269]

Thanks for your input. Does anyone make a torque arm setup that will weld in or that I can modify to work

[raustinss]

I'm pretty sure Chris Alston does

[BMR Sales]

Thanks for your input. Does anyone make a torque arm setup that will weld in or that I can modify to work

You can make anything fit with enough elbow grease! Not sure why you would want a Torque Arm in an A-Body though

[clu269]

You can make anything fit with enough elbow grease! Not sure why you would want a Torque Arm in an A-Body though

I get it. there are so many deafferenting opinions. I am looking for guidance and help in choosing the best option.

[raustinss]

The best aka easiest .. stick with the stock chassis , reinforce it with one of the 3-4 companies that make kits . Then use one of a bunch of companies suspension using the stock style triangulated 4 link . Again it might not be "the best " but you can pull a hair over a g on a skid pad with the right set up in these a bodies

- - - Updated - - -

Or go nuts and use a dobbertinperformance corvette IRS kit

[BMR Sales]

I get it. there are so many deafferenting opinions. I am looking for guidance and help in choosing the best option.

What I was getting at is that in an A-Body, you already have a 4 Link set-up that can be upgraded. a Torque Arm would defeat the purpose of the 4 link and bind everything in a ball!

A Body 4 Link

https://i.hmjimg.com/images/2018/08/13/s1.jpg

F Body Torque Arm

https://i.hmjimg.com/images/2020/02/04/_MG_2953.jpg

[clu269]

The best aka easiest .. stick with the stock chassis , reinforce it with one of the 3-4 companies that make kits . Then use one of a bunch of companies suspension using the stock style triangulated 4 link . Again it might not be "the best " but you can pull a hair over a g on a skid pad with the right set up in these a bodies

- - - Updated - - -

Or go nuts and use a dobbertinperformance corvette IRS kit

I already have the following for my frame.
AFX 1" drop spindles
SPC upper and lower control arms
Speed tech chicane kit
ride tech coil overs
6 piston baer 6P brakes
HPI frame stiffing kit.
I will be narrowing the rear and the frame kit id modified to connect to the rear lower control are cross tube to tie everything together.
If I can compete with the triangulated setup that is a plus. I just want to get the most out of the stock frame since I have the access to lasers, water jet and press brakes to fab anything I design on solidworks.

[jetmech442]

I already have the following for my frame.
AFX 1" drop spindles
SPC upper and lower control arms
Speed tech chicane kit
ride tech coil overs
6 piston baer 6P brakes
HPI frame stiffing kit.
I will be narrowing the rear and the frame kit id modified to connect to the rear lower control are cross tube to tie everything together.
If I can compete with the triangulated setup that is a plus. I just want to get the most out of the stock frame since I have the access to lasers, water jet and press brakes to fab anything I design on solidworks.

I had two major issues with the triangulated 4, which were resolved by the 3 link. The most important at the time was lateral movement of the axle because my tires would rub. As I got serious with the front suspension/brakes, I then noticed that I could never get the car to settle into a corner in time because the rear would oscillate several times until it damped out. It causes uncertainty in corners because the front will have planted happily, but the rear will still be moving mid corner, changing the loading on the tires. this cannot be fixed with solid(or poly bushings) in the uppers. The uppers need to have compliant bushings in order for the axle to roll without binding. The lowers shouldn't be solid for the same reason and in design shouldn't be accepting lateral load anyways-so this issue is inherent to the design of the Tri4. this doesn't really matter in a drag cause, you know, straight lines.

The other major issue is that Rear Roll center and Anti squat are directly coupled. Lowering rear roll center for a more balanced roll axis directly moves your Anti squat lower. In A bodies that have been lowered, the the upper arms angle down and increase antisquat. But this puts the roll center point into the trunk(with my edelbrock antisquat relocation bars, the roll center was actually near the torsion bar for the trunk lid. I've found the car is very stable and predictable when the roll center is about an inch above the axle centerline. Ina 4 link car that would mean the upper arms are angled upward(towards the front) and antisquat is, i don't really know at that point..zero? I'm not good enough to know, but I know I don't want whatever it is lol).

This is getting long,and I don't want to take up space on your thread if its not helpful, so I"ll just say that a watts or panhad bar can overcome the issues above -Almost-. I ran the watts for about a year with the Tri4. It completely eliminates the side to side movement, and lets you choose the rear roll center. Yes, I had two rear roll centers. 1 Physical(watts) and 1 virtual(Tri4 upper arms). the Watts wins right up until the uppers go into bind-then things get unpleasant. the settings to get into bind are not where I would normally run it, and if you keep the rear reaally stiff and damped, the axle won't move up and down enough to matter...but I wanted freedom to explore a wide variety of setups and the ability to quickly alter antisquat as well, so that led me to the 3 link. hope this helps, let me know if you have any questions.

[raustinss]

If you already have all of this make me an offer for my abc performance mini tub kit then replace the stock components with an engineered rear set up. Unless your dead set on wanting the absolute best stuff out there . At the end of the day a properly designed rear 4 link will give you damn near everything you want . I believe this has all turned into a giant pissing match ... aka the difference between a 500 whp engine vs a 650 whp. End of the day you're going to get everything you want and can actually use with 500 whp but , yes we all want to say we have 650 whp if you follow me

[clu269]

I had two major issues with the triangulated 4, which were resolved by the 3 link. The most important at the time was lateral movement of the axle because my tires would rub. As I got serious with the front suspension/brakes, I then noticed that I could never get the car to settle into a corner in time because the rear would oscillate several times until it damped out. It causes uncertainty in corners because the front will have planted happily, but the rear will still be moving mid corner, changing the loading on the tires. this cannot be fixed with solid(or poly bushings) in the uppers. The uppers need to have compliant bushings in order for the axle to roll without binding. The lowers shouldn't be solid for the same reason and in design shouldn't be accepting lateral load anyways-so this issue is inherent to the design of the Tri4. this doesn't really matter in a drag cause, you know, straight lines.

The other major issue is that Rear Roll center and Anti squat are directly coupled. Lowering rear roll center for a more balanced roll axis directly moves your Anti squat lower. In A bodies that have been lowered, the the upper arms angle down and increase antisquat. But this puts the roll center point into the trunk(with my edelbrock antisquat relocation bars, the roll center was actually near the torsion bar for the trunk lid. I've found the car is very stable and predictable when the roll center is about an inch above the axle centerline. Ina 4 link car that would mean the upper arms are angled upward(towards the front) and antisquat is, i don't really know at that point..zero? I'm not good enough to know, but I know I don't want whatever it is lol).

This is getting long,and I don't want to take up space on your thread if its not helpful, so I"ll just say that a watts or panhad bar can overcome the issues above -Almost-. I ran the watts for about a year with the Tri4. It completely eliminates the side to side movement, and lets you choose the rear roll center. Yes, I had two rear roll centers. 1 Physical(watts) and 1 virtual(Tri4 upper arms). the Watts wins right up until the uppers go into bind-then things get unpleasant. the settings to get into bind are not where I would normally run it, and if you keep the rear reaally stiff and damped, the axle won't move up and down enough to matter...but I wanted freedom to explore a wide variety of setups and the ability to quickly alter antisquat as well, so that led me to the 3 link. hope this helps, let me know if you have any questions.

This is excellent and make me want to move to the 3 link. I will be working on the Chassis in the next month and send you photos to critique as I go. You have spent the time guiding me to an outcome that took you possible years to come to. That is valuable and extremely unselfish.
Thanks for you honesty and forthcoming.

[clu269]

PM me on the mini tub kit. That maybe valuable I will research it since I have yet to look into this. I had planed on modifying my stock tubes.
There was certainly no intent for a pissing match. I am only looking to inquire knowledge.
Thanks for the offer on tubes.

[clu269]

I have finally made some progress. I have mocked up the ride height and got the frame kit installed. Frame rails are tacked and ready to install. the lower control arms will be mounted in the rear frame rails.


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[raustinss]

Nice work

[Mark@lateral-dynamics]

Interesting rear frame rails! Did you have those cut special, or does someone offer them for sale? We have a 65 El Camino that is going under the knife, probably not terribly soon but this is the main thing we are after too - much larger rear tires (well, front too.).

[clu269]

Interesting rear frame rails! Did you have those cut special, or does someone offer them for sale? We have a 65 El Camino that is going under the knife, probably not terribly soon but this is the main thing we are after too - much larger rear tires (well, front too.).
I actually made a template and traced them out on 11ga plate. i cut them out with a cutoff wheel and lasered out 11ga x 1.75 plate to achieve the 2" width. i would be willing to trace out the rails if you would like.

[chevelletiger]

Nice fab work!!

[clu269]

Nice fab work!!
Thanks I hope to have the chassis mocked up and sitting complete this winter. It take longer than expected when you continue to rethink the build lol.

[Mark@lateral-dynamics]

i would be willing to trace out the rails if you would like.

Hey, I'll take you up on that! Love the project, keep us updated!

[clu269]

Hey, I'll take you up on that! Love the project, keep us updated!
I will get these traced this Friday. once they are ready I will message you. I do plan to use my CMM scanner at some point to reverse engineer these. oce that is done I will have a DXF that can be used to plasma or laser these. I do intend to make a weld in clip to offer in the near future.