GM A-Body IRS
 

Since I have been working and reworking my '72 442 convertible for something like the last 15 years, I thought I might "upgrade" to IRS. Why not, right? I figure I will sell my Currie 9" to fund this little project.

So I figure I have six basic options.

1) C-3 Covette

pro: Uses the half-shaft as the upper control arm. This makes narrowing difficult, but it also alleviates the problem of upper control arm/frame interference.

con: The unit is difficult to adapt given the transverse spring, and trailing arms.

2) '69-'87 Jaguar

pro: Uses the half-shaft as the upper control arm. This makes narrowing difficult, but it also alleviates the problem of upper control arm/frame interference. Comes in an easily adaptable "cage." Center section is essentially a Dana 44. Readily available for little money.

con: Unknown axle strength. No trailing arm.

3) MN12 Thunderbird/Mark VIII

pro: Strong. Comes on a readily adaptable carrier.

con: It's 2" too wide. Not easily narrowable (cast lower control arms).

4) Mustang Cobra

pro: It's an inch or so narrower than the A-body rear. Comes on an easily adaptable carrier. Strong.

con: Known handling issues. Not cheap.

5) 200X GTO

pro: Easily adaptable. Inexpensive.

con: Strength (both the differential and the suspension components)?

6) Pontiac G-8

pro: Comes on an easily adaptable carrier.

con: Strength (both the differential and the suspension components)?

Remember, this is a bit of a Pro-Grand-Touring car; a backroad burner, long distance tourer, and not an autocross machine.

I was leaning toward the MN12, but after reading about the Jaguar unit, I think it might be a good choice. It even has the right wheel bolt pattern. I think the adaption of a trailing arm to the factory A-body might help with wheel hop?

Anyway, looking for thoughts and arguments regarding any of these.

Shiny Side Up!
Bill

Check out these links, a bit of info, not real in depth, but a good starting point for research.

http://www.rodandcustommagazine.com/...n/viewall.html

http://www.hotrod.com/howto/hrdp_071...s/viewall.html

Did you consider a C4 Vette Rear end type of set up? The gear case / center section is braced with a torque arm (like a 3-link) and the wheels are set up like a 4-link. Yeah a real oversimplification, but I've heard that most mods that narrow the set up still retain good geometry with a hub to hub measurement as narrow as 58 inches .

These guys do a C4 Vette suspension on 50's trucks and tri-fives
www.hotrodjim.com/trifive_c4_grand_coil.php

And there are a few other shops that do custom C4 Vette set ups. They mostly cater to Corvettes only but some have done other projects.
http://uscorvetteconversions.com/

http://www.progressiveautomotive.com/

And one of the guys in our club has a 69 Camaro with a BMW 7 series IRS. He liked it because it had the huge brakes, and the right hub to hub for his project. He went with cantilever shocks in the trunk. Quite a project but it looks sick, and it handles great.
http://pacificfab.net/barry-camaro.htm

The C-4 looks nice, but very pricey.

The more I read though, the more the GTO rear looks like a good choice. Though he's never posted anymore on it, DDT RCKT put one in a a '70-'72 LeMans (shares a frame with my 442). Here is the thread on it.

Hmmm.....


Shiny Side Up!
Bill