It's been some 14 years since gave up on my 4+3 trans and swapped in my T56. Last year I re-ignited a project to update my old Vette with some needed horsepower. And while I had everything torn apart it seemed like a good idea to update the clutch assembly too. My new/old engine is a two piece rear main seal (400 sbc) so that requires a special flywheel to mate to the T56. I managed to pick up a Fidenza aluminum FW #198661 for a song and figured I'd step up to a Spec 3+ clutch to match. My setup still uses the F body external clutch slave cylinder connected to the factory Corvette clutch master. I can't remember why, but I must have disconnected the two because I spent an inordinate amount of time trying bleed the air out of it.

Here's where things went sideways: Even after bleeding it several times over, the pedal didn't feel quite right. In the mean time work on the engine continued, there's always a hundred things that need to checked, changed, or modified. Finally I'm getting the point where I can start this critter up and get it off jack stands. PROBLEM: the clutch is NOT disengaging. My next act was to determine if the clutch fork was actually moving so whipped up a little brace, in lieu of the slave, that would hold the fork in/open. No dice - so the problem isn't the slave.

Ugh, so back out the exhaust, drive shaft, "C" beam, transmission, bellhousing to see what's going on.

As you can see my new Spec clutch is now sport a nice grind stripe. An here's the culprit. My clutch fork is hitting the pressure plate. WTF?

So I ran to the internet to see if someone had encountered a similar issue. I did find a post on the Chevelle Forum with basically the same problem and the fix. My stock F Body flywheel looked to be about 35.3 mm thick, with the Pressure Plate 42mm, total 77.3mm The Fidenza FW was 36.9mm thick, and Spec PP 43mm thick, giving me a total of 79.9 A good 2.6 mm bigger than stock. The fix was to reduce the height of the clutch pivot fulcrum. The Chevelle Forum took off 1/8" so I ground about 3mm off the bottom. I did also smooth out the ridges on the fork where contact was made, not much maybe only 1mm, so as not to weaken it.

Wrestled everything back together, crossed my fingers, and it worked. The clutch pedal feels normal and it does disengage. Now here's the caveat: I have not road tested this yet, so I don't really know where my engagement point is regarding pedal travel. With any luck it should be manageable. I'll update if this all goes to hell.

 

Seems like a good fix! How's the throwout bearing on that setup? I ran an Lt1-style T56 like that for years behind a Vortec 350 and no matter what brand throwout bearing I ran it was always super noisy.

 

I didn't notice any additional noise from the Camaro "pull-style" clutch/throw out bearing. The old 4+3 was dismissed quite a some time ago so any noise comparison would be a faint memory. My new exhaust is bit on the loud side so I'll never hear the throw-out bearing even if it's screams in agony.

 

I had to unbolt my slave from from trans hold it Vertical with bleeder valve open. Compress the slave cylinder forcing the fluid up and out the bleeder that is up. Tighten the bleeder screw.
Then check your clutch pushrod throw for the master cylinder, to make sure you are getting the full stroke on the master. I had to lengthen mine about 5/8 inch to get full stroke. After that it worked beautiful. But save your custom length rod because you will need it when you replace the master. Even better if you make it adjustable.