Replacing the clutch in the C4 Corvette

The clutch on my ‘96 LT4 has been getting progressively worse for the past few years, and now it’s gotten bad enough that I’ve decided it’s time to think seriously about how I’m going to fix it. It’ll hold for normal driving and while it’s cold, but after it has gotten warmed up it’ll slip with prodigious throttle input on the 4, 5 and 6 gears. I bet if this were an LT1 it wouldn’t even have this problem, it’s just not up to the task for a strong LT4. I bought this car at 126k and have driven it for another 30k like someone who knows how a clutch works, but it had been through a lot of previous owners and since it goes like stink I’m betting the clutch has been abused along the way. I doubt it is the original and I have no way to know what it’s been replaced with.

I’ve done clutch jobs on transverse setups before, but this will be my first longitudinal. I’m aware of this being a dual-mass setup and that you’re supposed to replace everything including the expensive (>$1000) dual-mass flywheel, but that seems excessive for my situation. In the past I’ve been able to clean up the flywheel with some fine sandpaper, air-powered polishing pads like what I use to clean up cylinder heads, and/or a rotary wire brush on a drill. In light of how minor my issue is, I am hoping that a flywheel cleanup and a new clutch disc and/or pressure plate will take care of it.

It takes a lot of coordination and planning to make a project of this scale happen. I got the clutch kit on closeout at RockAuto in a Beck/Arnley box, but to my great satisfaction inside was a VALEO. With that part out of the way, next came the question of where to do it.

My friend’s shop I would need to use for this was tied up until the LeMons race at Thunderhill last weekend and I couldn’t really work on it until that was over. I got it torn down during the past week and what an adventure it’s been. It’s going to be tough to get it back together as nearly every exhaust fastener broke taking it apart.

I finally finished getting the trans and clutch out of the car, and I never could have guessed what went wrong. Of course, both the pressure plate and flywheel were badly burned. But the real surprise was the clutch disc itself, which pointed to an unlikely culprit for the cause of all this.

The first strange thing about the clutch disc was that it actually looked pretty good. No burns, no shiny spots on the pressure plate side, and plenty of thickness before it got to the rivets. But on the flywheel side, it looked like an LP record: the outer 1/8″ was shiny, and the radial grooves across it were worn unevenly. I had a hunch what this meant, and a straightedge confirmed it: the flywheel had warped into a concave, dish shape.

I will not be attempting to resurface it. I’m checking for a quality used part first then ordering one from RockAuto if nothing turns up.

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