GM G Body three link

[lachowich]

I had heard that SC&C were working on a 3-link rear suspension for 1983-1988 GM G Bodies but it seems like its not going to be available in the near future. I've done a lot of research and it doesn't seem like anyone has a kit that would be easily adaptable to these cars at all. At this point I'm going to go ahead and try to figure out how to make my own. I just need a little help from anyone who might be knowledgeable in this area. *If anyone has done this to an earlier A body their help would be greatly appreciated as well because thats probably the easiest place to start (similar frames and suspension)

What I know:
-I want to be able to use the stock rear seat without cutting into the upholstery. Minor trimming of the floor, seat frame or seat foam is ok.*
-I don't want to use the transmission crossmember as my pivot point for the torque arm.
-I want to use adjustable coil-over shocks mainly for packaging to make stock appearing rear exit exhaust possible.
-I want to use rubber bushings at the housing end to minimise NVH
-I don't care if its bolt in or weld in construction
-I want to use a watts-link
-The rear of the car should sit 1.5 - 2 inches lower than stock.
-I fully expect to have to do some major reinforcing of the frame, box in the C-Channel etc

What I don't know:
-How long should the torque arm be?
-How long should the other two arms be?
-Do the lower two arms need to be exactly parallel?
-Important angles?
-Should I use an F-Body 3 link rear end housing or?
-Are any F-Body parts or aftermarket F-body parts worth modifying to use?
-Swaybar? Yes? No? Mount to?

Any help would be greatly appreciated. I'm probably in over my head but I'm willing to learn. I'll document every step of the process and make detailed plans available to anyone else who wants to do this.*



http://www.rrs-online.com/3linkproducts.php
This is the closest I've found to what I'm trying to do. *

Failing this I'm actually toying with independant rear suspension. Something like what team321 offers. It might actually be easier but its got a lot of drawbacks. http://www.team321.com/321HotRodIRS/...odIRShome.html
But probably with the LCA shock mount so I can run stock appearing rear exit exhaust.
http://www.team321.com/321HotRodIRS/...untImages.html

thanks in advance for any input.
- Steve

[lachowich]

One thought I've had is to start with a crate f-body three link rear end custom ordered to the width I need. I would then have to build my own control arms and add the coil over mounts. Is this possible or is there a better way?

[oestek]

What do you plan on doing with the car? The 4-link is a pretty nice suspension design, and with arms like the DSE Swivel-Links you can really make one articulate nicely. Those are available for A bodies now, don't know about G bodies, though.

[megaladon6]

i'd look into how GM set it up on the GNX.

[6spdmalibu]

Here is some info on the GNX suspension. https://secure.mysuperpageshosting.c...ce.com/gnx.htm
Only problem is you'll have to fabricate everything from scratch as this kit is no longer available. I like the idea of a torque arm but the ground clearance might be an issue?! What will be the intended use of the car?
Checkout the decoupled torque arm setup http://www.f-bodysport.com/decouple_torque_arm.htm as an alternate.

[megaladon6]

looking at the GNX setup i'm thinking you just need to fab a torque bar and then use the sc&s watts link instead of the panhard bar. which should simplify things. admittedly i know almost nothing about this, but i think the only hard part will be the front mount of the torque bar.

[lachowich]

The car is currently and will always be a street driven car. Its not a daily driver or anything like that though. I would like the potential to do the odd autocross event. I put a lot of research into doing something with the factory 4 link but there are just too many compromises to be made to still use it. The only aftermarket control arm assemblies made specifically for this chassis that I like at all are the Currie Currectrac setup with the johnny-joints. Rod ends are too stiff for my liking. It just seems no matter what you do the four link still has a tendency to be in a state of perpetual binding.

The GNX setup is interesting. I never realized that they used the factory lower control arms. The idea of having a seperate cross member with a driveshaft safety loop is pretty much what I was planning. I just need to know where to locate it or how to figure out where to locate it for the best suspension geometry. I wonder if I could order a hybrid F-Body/G-Body 12 bolt rear end (I need to upgrade to a 12 bolt for strength anyways). This hybrid rear end would have the F-Body torque bar mounting locations and the stock G-Body lower control arm mounting points. I could then use the Currie Currectrac lower control arms. All I would have to fabricate then would be the cross member and the torque arm itself. Oh and of course add the watts-link and the mounts for the coil-overs. If i knew the length of the stock lower control arms is there a formula to figure out what the length of the torque link should be for optimal handling? Am I oversimplifying things?

Some info on the car as it sits already:
GM ZZ383 crate engine
700R4 Transmission (built)
UMI Performance tubular lower control arms (Front)
SPC upper control arms (Front)
QA1 12 way adjustable front coil-overs with 550 in/lb springs (these mount to the factory upper spring mounts, not a true coil over)
SSBC brakes, stainless lines, etc
Steering rag joint removed and replaced with U-Jointed steering shaft
The usual poly bushings and mounts in the front end, rebuilt steering linkage, etc.

[Samckitt]

Kirban Performance used to make a reproduction setup of the Grand National GNX rear suspensions.

https://secure.mysuperpageshosting.c...ce.com/gnx.htm

I don't see it on their website now though.

[lachowich]

I'm pretty sure that kit is out of production. Did GNXs use 10 bolt or 12 bolt rear ends? I'll try contacting them to see if I can get any measurements from them at least. Its probably a good starting point anyways.

[novaderrik]

the GNX used the same 8.5" 10 bolt as every other 84-87 turbocharged Regal, except it had the special aluminum cover with the torque arm mounts and a panhard bar mount added on one side.

[lachowich]

Thanks. I really have my heart set on a 12 bolt so theres no sense in trying to get a hold of one of these kits then even if they did turn out o still be in production.

[BillyShope]

-How long should the torque arm be?
-How long should the other two arms be?
-Do the lower two arms need to be exactly parallel?
-Important angles?
- Steve

http://www.racetec.cc/shope/tim.13.htm
http://www.racetec.cc/shope/tim.22.htm
The above might help.
http://www.racetec.cc/shope