Common front susp mods for a C4?

[C10CoryM]

Hey guys, I am building a little hotrod that is likely going to use C4 front suspension with solid bushings and coilovers. I will be seeing some track time with it and I am just wondering if there are some mods that are commonly done to correct factory imperfections. Things to reduce bumpsteer, reduce unsprung weight etc. For brakes I think the stock brakes will be plenty for now. Car only weighs 2300lbs(est.) I can always upgrade later if I need to. Is there somewhere online that has a corvette junkyard that I could buy a whole front clip from? If there is a autoX/roadracing forum around for C4 vettes please direct me there too.
Thanks for any help.

 

[vader86]

Usually, we just go to Z51 or bigger swaybars, and poly bushings, then the camber brace. Check out VetteBrakes', they are the place I always go to look for better parts. They should have anything specific you want.

I hope youre talking about the brakes from the 88+ models, those are a bit better than the 84-87 brakes.

 

[C10CoryM]

Camber brace huh..... didnt know they were weak in that area. What part actually flexes? It wont be a concern on my car since it will (hopefully) be properly triangulated but always nice to learn. Thanks for the help. So far it sounds promising. I am going to have to beg someone to do some real quick measurements for me. The suspension is the same from 84-96 with better brakes from 88+? Or did it all change in 88?
Thanks for the help.

 

[vader86]

No the suspension geometry changed in 88, but is the same thereafter.

GM decided to go a different route than they had the 84-87 years. They were using stiff springs to give handling, and in 88 they changed their philosophy to geometry changes and bigger swaybars and improved alignments to give the same handling. The components in the front are not interchangeable between the 2 designs, though I think the rear almost entirely is.

The Camber brace is put in because the upper control arm bolt is so far away from the crossmember, and in cornering, it feels the most force and tends to flex. By putting it in, you remove flex from the control arm mounting horns.

 

[Tuna]

Check out http://r-dracing.com/Camber-brace.htm for their front suspension brace. It just might fit your application.

 

[C10CoryM]

Thanks for the info guys. I will be building my own crossmember rather than splice the stock one into my chassis. Much cleaner and stronger that way. On this car there is not much in the way of the front suspension. The engine sits very far back. I can properly stiffen the front end without any troubles. I am going to have to look into which C4 susp I like better. It will probably come down to whichever I can get my hands on cheaper/faster. I may just buy a wrecked car as I also need a diff and some other stuff. Does someone happen to have a list of measurments for the C4 front susp? Centre to a-arm pivot, centre to balljoint etc etc? Otherwise I will have to beg one of you guys to do a few rough measurements for me . I need the rough measurements so I can final design my chassis on the computer. The car is going to be based on a 64 cheetah with modern drivetrain/suspension. You corvette guys should know what a cheetah is since it was mostly vette parts
Thanks again guys.

 

[C10CoryM]

Just a little update incase anyone cares. Apparantly I have good luck as a 91 vette came into the shop today for me to work on. On the test drive I was very happy with the way the front end handled, I did get some jacking from the back which I expected, and the steering wheel had far too much movement on bumps to it. I hate it when the wheel moves around when you hit bumps. Makes me feel like the steering is not solid enough. After driving it though I think GM really hit the nail on the head with the front suspension. It responds very well. I think with my mods it will be a very good setup. I also got a chance to measure what I needed for now to get my chassis designed. One more Q though, the rear end in this 91 vette automatic, convertable.... would that be a dana 36? I will also be needing a IRS differential for this car. I think a dana 36 would be up to the task, but if the weights/size of the dana 44 are close I may go for that for extra insurance.
As always, thanks for the help.

 

[vader86]

Yes its a D36. It will be fine for most street applications.

Depends on how much torque you want to put through it, though anything in the low 400s 'should' be ok for any street driving. Just know that if you take it to the track, its gonna blow anytime it feels like.

 

[C10CoryM]

Well, for now I am running a 420hp 377ci from my camaro but I am planning on upgrading the engine after the car is built (Ill probably blow it up and have to build it again anyhow, wouldnt be the first time :eyerole ). So Id like my drivetrain to be able to handle 500hp with no launches. It will be running on street tires for most of the time with race tires for the road course. Keeping in mind the car weighs almost nothing with fairly narrow tires (255mm) and very light rotating mass so traction is going to be non-existent. What can the dana44 handle in stock form in a corvette? The other route is to get a 8.5" 10bolt built. I know that will handle anything this car will do to it but it wont be cheap to convert it to IRS. Id sooner have a dana44 which I think could handle it.
Thanks.

 

[vader86]

The D44 will handle that amount of power.

They can handle slicks on cars running 9's, so I believe youll be ok. Cryo-treating would make it even a little tougher.

 

[C10CoryM]

Cool, I figured a dana44 would be plenty. Couple more Qs and I should know enough for now. Whats the ratio of the steering rack from a 88+? Or how many turns of the steering wheel does it take to go from lock to lock? I have minimal elbow room so I need a pretty high ratio box. I will leave room for a steering quickener if I can. I assume all 88+ are power steering? Are they variable rate (get harder to turn at higher speeds)? If so I will have to figure out a way to wire it from a speed sensor (you happen to know if it uses a vehicle speed sensor or a steering wheel speed sensor like the newer one?). Last thing I want is full P/S at 140mph in a 90" wheelbase car. I would like to stay alive after all . Thanks for the help Vader. I help people a lot on other forums so its great to have the favour returned .
Cheers.

 

[vader86]

If I remember correctly, its 2.5 turns lock/lock for a Z51 car. Its something like 2.75 lock/lock for non-Z51.

I used to know the ratio, but I forgot and I cant find it anywhere, someone will know.

Yes its a rack&pinion power assist for all of us.