Only 3 years?
When my brainstorm hit me was when I was at a car show at a local Chevy dealer several years ago. There was a blue C4 vette there with the hood flipped up and I was looking at the suspension pieces....it amazed me that they were all aluminum. I thought it would be great to use the a-arms and whatever else I could use on my Nomad. At the time I didn't even know anyone was already doing these conversions, but I searched the internet and found a Roush Engineering website and they were doing one for a tri5 using the 4 plate method you are using. Not long after that I got a Super Chevy or CHP magazine and there was a red C4 conversion frame on the cover. It was Roush's. That's when I decided to move forward with my Nomad. I spent weeks laying it all out to make sure everything fit, after I bought the suspensions and took measurements. Today it seems like such a simple thing.
If by track width you're referring to the tire centerlines, they're kinda close. The tri5 track width is 58" in front and 58.9" in the rear. The late C4 is 59.6" in front and 60.4" in the rear. However, the wheel mounting surface is quite a bit wider on the C4 than the tri5 as you probably know.
I took my measurements on the outside of the tires front and rear. I have aftermarket wheels and tires and dropped spindles in the front so mine is already wider than stock. Our 90 Vette is the same in the rear and just a tiny bit narrower in the front.
just roomy.
A '90 vette coupe is 3255 pounds and a convertible is 3301 pounds curb weight. The ZR1 was 3479 pounds. A stock 55 Chevy 2-door BelAir sedan is 3285 curb weight with a 3-speed. A C4 suspension will knock 150 pounds or so off of that.
I weighed both cars at the local race track (Paved stock cars) where I work part time. I don't remember the exact weight but my 55 was about 190 lbs heavier. Should be pretty close with the weight savings the C4 suspension has. The weight at each wheel is very close also so the front to rear balance is very close also (Stock cars are weighed on a separate scale for each wheel)
I do plan to use the Corvette springs, but have the upper shock mounts set up so I can convert to coilovers if needed.
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a swaybar that has shorter arms, or shorten the C4 swaybar arms. That will make the swaybar stiffer so I'd use one of the smaller diameter ones. Another solution is to use a different gas tank. I've done that and mounted it to the frame instead of the body. If you need a new tank anyhow, it's a good solution.
Keep up the good work and keep us posted on progress.