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I (think) the chassis is the same on all C4s. Spring rates, shocks were changed. I am basing this on what I read about different year C4s and the hard ride complaints. The 84s rode the worst, but was one of the best handling C4s.
Major changes in 88 for the front suspension and revisions for the rear. First, the 17X9.5 wheels were introduced, the 16X8.5 was standard. The Z52 pkg included the 17.5" wheels. The 0 scrub radius front end incorporated a steering radius that intersected the road at the exact center of the tires contact patch. One of the proposed benefits was better directional control under hard braking. The rear suspension got more rebound travel and reduced camber. Brakes were upgraded also w/larger rotors and dual piston calipers with the Z51 and Z52 pkg. You could start an argument as to whether the 0 scrub radius redesign was better or not, but regardless, it was still the best handling car on a road course, the ride was better and the Vette was still the best bang for your $.
Inner structure components for C-4 were constantly changing. Callaway discussed this some at one of his seminars. Structural rigidity increases were large between 86 and 89. Part of this was most likely due to needed increase for coming ZR-1!! Also it is well known that C-4 was originally engineered for non-removable top and then changed causing a large loss in structural rigidity!! Also entering into this was changes for air bag systems!! So hardly a non-changing design!!
Inner structure components for C-4 were constantly changing. Callaway dicussed this some at one of his seminars. Structural rigidity increases were large between 86 and 89. Part of this was most likely due to needed increase for coming ZR-1!! Also it is well known that C-4 was originally engineered for non-removable top and then changed causing a large loss in structural rigidity!!
Didn't many members make more notice/complaints of cowl shake in the later years (as opposed to the earlier)? We there any differences attributed to the Z51/Z52 option?
You could start an argument as to whether the 0 scrub radius redesign was better or not,
Well I can understand the reason to change to 0 scub and more predictable braking. But can anyone tell me the "cons" of 0 scrub or the plusses of the earlier suspension geometry?
I don't have my books handy but I do remember that GM gave the SCCA SOLO(?) national champion a 88 model to replace his early model C4, and after trying it out he gave it back and he returned to the older C4. I also read somewhere long ago that the other reason for the change was that it reduced the number of parts in the front end , therefore saving production cost. The 0 scrub radius was just a byproduct of the redesign. The cars year by year were softened, if you look at spring rates, caster, staggered tire sizes in the base suspension and lower tire pressures to soften the ride, the changes made the vette a better road car in more of a GT vein. GM caught a lot of flack from the press for the early vettes ride qualities but on a closed course they were near impossible to beat.
The chassis itself is basically the same. They added some extra bracing for the convertible and this extra bracing was also used in the later Z51and Z52 cars. Of course there's lots of little differences over the years.
Dave McClellan, Cheif Corvette designer from 75 to 92, came to an SAE meeting at Texas A&M University last week, and I asked him about the front suspension change. He said the change from positive scrub to zero scrub was to work better with ABS. He said that the positive scrub setup would jerk the wheel when ABS was engaged, and thus it was changed to a zero scrub setup.