I have done many C4 suspension installs in a wide variety of vehicles including a 40 or 41 (been to long, don't remember exactly) Chevy coupe.

Cars like these are fairly narrow so go with a 85-87 suspension. In 88 they got wider, and in 93 the geometry was changed but they are still wider than the 85/87's. In 84 they have the parking brake internal in the rotor with shoes like a drum brake which can be a hassle.

Use the factory Corvette crossmember in the front, and install it so the tie rods are level at ride height, and the crossmember is level front to rear with the frame at the proper rake. If you use the stock front spring you can shim the outboard end to raise the car if necessary, or remove the shims on the frame mounts to lower it a bit. You will have to build upper front shock mounts.

For the rear, I install mine so the toe adjusters are level at ride height. The hub centerline on the rear is about 5/8" further rearward than the output yoke on the third member when installed properly. Use the stock Corvette frame mount for the trailing arms, and at ride height the upper arm is angled down toward the front about 30%. You will have to "C" notch the frame to clear the toe adjusters if the car is to be low. I have had good luck running the stock composite springs with these conversions, and they ride very well. You may have to put longer bolts on the rear spring to lower the rear end if necessary.

Use the stock front and rear anti-roll (sway) bars too!

Good luck!
Andy

 

Why re-invent the wheel? Progressive Automotive has complete kits down to individual parts...

Russ

 

Why re-invent the wheel? Progressive Automotive has complete kits down to individual parts...

Russ

Possibly because it is fun to do it yourself, and it's much cheaper.

 

I have done many C4 suspension installs in a wide variety of vehicles including a 40 or 41 (been to long, don't remember exactly) Chevy coupe.

Cars like these are fairly narrow so go with a 85-87 suspension. In 88 they got wider, and in 93 the geometry was changed but they are still wider than the 85/87's. In 84 they have the parking brake internal in the rotor with shoes like a drum brake which can be a hassle.

Use the factory Corvette crossmember in the front, and install it so the tie rods are level at ride height, and the crossmember is level front to rear with the frame at the proper rake. If you use the stock front spring you can shim the outboard end to raise the car if necessary, or remove the shims on the frame mounts to lower it a bit. You will have to build upper front shock mounts.

For the rear, I install mine so the toe adjusters are level at ride height. The hub centerline on the rear is about 5/8" further rearward than the output yoke on the third member when installed properly. Use the stock Corvette frame mount for the trailing arms, and at ride height the upper arm is angled down toward the front about 30%. You will have to "C" notch the frame to clear the toe adjusters if the car is to be low. I have had good luck running the stock composite springs with these conversions, and they ride very well. You may have to put longer bolts on the rear spring to lower the rear end if necessary.

Use the stock front and rear anti-roll (sway) bars too!

Good luck!
Andy

Thank You for the info!!

This is very helpful!

 

Possibly because it is fun to do it yourself, and it's much cheaper.

Admittedly it is fun to do, but not necessarily cheaper. Consider materials, your time, and mistakes along the way... Plus you won't be having the benefits of an "engineered" system.

Russ

 

Admittedly it is fun to do, but not necessarily cheaper. Consider materials, your time, and mistakes along the way... Plus you won't be having the benefits of an "engineered" system.

Russ

The way I see it, if you enjoy the process, the time is free. A little bit of steel stock is much cheaper than any fabricated crossmembers. As to the "engineered" system, if you stick to the factory configuration and set-up you won't go too far wrong. I have worked with a lot of junk aftermarket suspension systems that looked pretty but had serious issues.

I have spoken to many suspension system fabricators over the years, and it is funny that when you start asking questions such as what is the camber gain, how much bump steer is built in, what wheelbase is the ackerman designed for etc how they can get quiet real fast.

I will admit there are some excellent aftermarket suspensions systems out there, but you do have to pay for the engineering and the quality. In the case of the C4, that is why I prefer to use the factory front crossmember and the stock rear geometry if it will work for your project. GM paid for the engineering, and we get to reap the benefits.

Andy

 

C4 Suspension

Hello

I am currently installing a 1990 C4 front and rear suspension in a 48 Chevy P/U. I haven't started on the rear yet still cutting & welding the front. There are a few things to watch out for. Are you using the Corvette front cross member?