I have a 93 base model with a ZF6 transmission. I am going to be replacing my clutch and flywheel at 117K miles shortly after Christmas with a SPEC Stage 2+ and single mass steel flywheel. Through the research I have done it seems like I will also want to get a new clutch fork and pivot stud in case I discover mine is bad after taking it all apart. (I can't afford to have too much down time on the car because it is my only vehicle.) I cannot find anywhere to source these parts though.

My question is: Will I most likely need an new clutch fork and pivot stud? There are no current issues with how the clutch functions it just doesn't catch like it used to and I am also about to do a heads/cam swap and want the drivetrain to be up to the task.

If you think I will need a new clutch fork and pivot stud, where can I source these parts?

Also are there any other supporting parts that I should replace while I am there that won't be included with the spec clutch? This is my first clutch replacement so assume that no part is too obvious to need to be pointed out.

Thank you for all your help in advance.

 

From my experiences...the clutch fork and pivot ball were fine. I can not think of one time that I needed to change them out during a clutch repair service.

For what it is worth...do not throw away your flywheel. the reason being that if it is not leaking from the bushing and its free play is within limits...it can be used...JUST IN CASE that when you get the solid mass flywheel and clutch installed...that the noise the transmission puts off is more than you like.

I use SPEC clutches and I hope you got the heavier flywheel from them.

DUB

 

I have not ordered anything yet because I am going to be out of town over Christmas and New Years. I was honestly debating between the steel flywheel without the extra mass and the aluminum flywheel. I'm not worried about the noise. My car already has plenty of exhaust drone and wind noise from the weatherstripping that I have just gotten used to stuff like that I am mostly just worried about the drivability of an aluminum flywheel on the street and that it would make it more difficult to launch at the strip. I feel like the normal steel flywheel would be a good compromise.

Thank you for your input on the pivot stud and clutch fork also.

 

Using a fadanza Aluminum flywheel made a huge difference in how fast she REV's. There was something like 33lb weight difference between the Alum. and Dual mass.

The down side to that was, I experienced chatter for the first few hundred miles and ofcourse the noise when the clutch is released in neutral.

I like my fadanza now that it has broke it. Glad I got a good REV limiter.

 

This is a very knowledgeable resource on the ZF6 clutch assembly. I bought my Spec flywheel from him, as he machines it, balances it on an LT1 crank, and counterbores for the factory PP bolt holes.

He also bought up the remaining NOS parts from GM when they stopped making them in '06. He told me he was working on manufacturing the pivot studs, not sure if he has yet or not. But he may be able to lead you in the right direction. His name is Jim Jandik

http://www.powertorquesystems.com/

I just replaced my clutch and flywheel, same set up last spring. Because I had already replaced the pivot stud at one point, I made the assumption it would still be good. This was not the case and I had to do it all over again. If your on a tight schedule, I would highly recommend locating these parts before you start.

 

It would be nice if someone would manufacture a HIGH quality throwout bearings for both the Vette and Fbody pull type clutches definitely a market for them!

 

The shipping weight of my lightweight billet steel flywheel from spec was 21 or 22 lbs; the stock dual mass flywheel is what 35 plus pounds ?

Granted an aluminum flywheel can weigh in at 12 to 14 pounds. But sorry, I'm not a fan of aluminum flywheels; too many horror stories from back in the day about them fracturing and grenading. If you race and run an explosion proof bellhousing, well that's another story.

Seemed like a 22 pound billet steel flywheel was a good compromise weight wise AND safety wise.

I definitely agree that running down a new pivot ball and clutch fork is the way to go.

I personally installed a Spec 3 plus clutch and love it; of course I'm a big fan of metallic clutch discs

 

Thank you very much this is exactly what i was looking for. I will call him and talk to him about what I should do.

 

Billet steel in the 20ish anything lb range is perfect for a street car. Heavy enough to store energy and light enough--

 

i'm really happy with the 22lb wheel. Still nice and easy in stop and go traffic, but with the lighter rotating assembly, it's almost as good as a gear change on acceleration.

 

The link above provided significant information about 6 speed part location problems - expensive resolution to clutch issues. Are there any replacement transmission solutions that can be applied to the C4?

 

After working with jim, im not sure i trust his motives.

While he is definitely the go to for clutch hydraulic parts, i would take his clutch advice with a grain of salt...

For example: he claims that spec clutches are the worst things ever.

Fact is spec does have a good product for us and that is the spec stage 3+.

Sure, the pressure plate comes from a different source than it did 6 years ago, but that doesnt mean its not going to work.

The new one (made who knows where) is working fine.

The only thing i caution is to be sure and balance your pressure plate to your flywheel because mine reqd more balance weight (than the prev valeo pp did).

Jim will try to sell you a carolina clutch stage 3 puck style, and he will get angry if you ask him about the spec.

Jim will also try to steer you away from the alum flywheel. In reality, the flywheel is not the cause of the noise.

The cause of the noise is countershaft gear buzz. its just that the heavier flywheels do a better job dampening it. The correct fix is a thicker shim from zfdoc.

I installed the thicker shim and all rattle went away -even with the alum flywheel i run.

The next concern is the throwout bearing. I got a china one and it seemed sloppy compared to a made in usa nos one that i also had.

spec is reproducing what appears to be a bhigh quality replacement that is not sloppy like the made in china one. It comes with their new kits (at least it did on mine when i ordered it in 2012).

That said, i am using the new old stock made in usa throwout bearing since i had one.....

 

One consequence of the alum flywheel is you have to downshift sooner when climbing a hill......

Another is that its harder to drag launch. However i have learned how to slip the clutch a little....

That said i still like mine

 

well theres no better way to scare someone about a part than to say its gonna hurt them....

This is the first time i have ever heard anything like that.

Have you seen an aluminum flywheel? The friction surface and flywheel teeth are steel.

Im happy racing with my alum flywheel. Ill see the steel flywheel guys from the other side of the line!

 

Thanks I feel like I'm getting a lot of good information here. I think I will order the Spec clutch and flywheel through SPEC and then I will order the pivot stud and clutch fork from Jim. I here a lot of people saying that the SPEC Stage 3+ clutch is the one to go with. The Stage 3+ according to SPEC is rated for 845hp and that seems just a little excessive for my application. I was leaning towards the stage 2+ which is still rated at 665hp to save a little money. What do you guys thing of a Stage 2+ clutch for an aggressive heads/cam application (approximately 400rwhp)

 

Is the stage 2 the kevlar one? If so i broke the hub out of one on my head/cam occasional nitrous hit car back in 06. About 10k miles on it

It was a great clutch up until that happened...

Be sure the clutch you get is full faced disk (not the puck or fan blade looking ones) and sprung hub because you will be eliminating the heavy duall mass flywheel (use that pos as a boat anchor). The sprung hub will absorb driveline shock.

I dont know what to think of the 845 hp claim of spec for stage 3+. Most people do twin disk clutch at that power level

Good luck

Im on my 3rd clutch

 

Stage2 should be more than enough
Running a lousy dual friction single disc centerforce with sticky tires never slips or chatters;fairly stout solid roller 383
fwiw
Most clutches will take another 50+ lbs of torque more than they are "rated" at to cover the mfr.

 

Cuisinartvette brought up a good point about throwout bearing. I put a new clutch, T/O bearing, pressure plate in my 89 quite a while back. With in 5 K miles, the t/o bearing came apart. Had to pull it all out again. This time I ordered a Delco t/o bearing. When comparing the two, the Delco was noticably beefier than the first one. I am told that they are hard to find now and more expensive, but tearing it all down within 5k was a pain in the ***. I wish I would have snapped a picture of the two sitting side by side.

 

Hey Diz, it's cool man. I don't know what your conversations with him were, but he never said anything bad about Spec clutches to me.

His motives are pretty clear, to sell parts. But he is a C4 guy and understands these cars pretty well. He is well spoken of among some others that he referenced me to when I was looking for a pivot stud.

He took a fair amount of time discussing the ins and outs of the proceedure with me, even when he didn't have to, and I didn't really expect him to. He gave me alot of very useful info, and just seemed like a nice guy to me.

 

Jim has been very helpful to me. He rebuilt a clutch master and slave cylinder for me and it works great.

He also helped me locate some new old stock clutch parts.

Heres the issue i had:

we were discussing clutch options and he kept trying to push off a puck style stage 3? clutch off onto me.

In fact, it wasnt even a sprung hub. He knew i had replaced the dual mass unit with an alum flywheel.

Its common knowledge that a sprung hub clutch is required when you get rid of the dual mass flywheel to dampen driveline shock.

I know enough about clutches to know that puck style clutches are not at al street friendly vs. Full faced.

I told them i thought the full faced sprung hub spec stage 3+ would be a better choice for me.

I needed to buy some other parts and he refused to sell them to me because i didnt buy a clutch (that would not have been optimum) from him.