So I recently picked up an '01 Z with some work done to it...head/cam/exhaust and a clutch/flywheel. The clutch is a Centerforce DF clutch, don't know if it's 11 or 12 inch, and it's not behaving like it should.

Driving around town, it's fine, although it is very hard to depress the pedal (like a race-clutch) and it engages right off the floor. When revs go higher...over 5500rpm or so...the car won't shift until the rpms drop.
So I do 'The Test'...car at rest, push in clutch all the way, put in first and rev to 6K...the car creeps forward. I put in reverse and the car creeps back. OK...the clutch is not disengaging 100%. I bleed the clutch (thankfully the PO had a remote bleeder installed) a couple of times and there is no change.

Checking around the forum I find out that this seems to be a common, or at least a similar issue, with other CF/DF users. Some have used the TICK adjustable clutch master to help (it pushes more fluid to the slave which disengages the clutch more) and some it doesn't help. I call TICK and they say it may work, but it's really the clutch design with the weights on the pressure-plate that cause the clutch to hang-up and not fully disengage at high rpm...so the weights help clamping force at higher rpms but they do it too good. Word is that some people remove the weights or some of the weights.

I call Centerforce. They admit that the DF clutches have had issues with the F-bodies not fully disengaging and removal of some/all of the weights have helped. I ask if they've heard of any issues with the vettes and they say 'NO'. Problem is, in order to take the weights off the clutch, I still need to have the driveline disconnected, and if I go that far I'm not going to chance the clutch not working right without the weights and I'll just replace the clutch with another unit.

So I ordered the TICK adj.master - I'm hoping that the extra fluid will allow the clutch to disengage a little bit more and give me the proper release at high rpms. I figure if it works then great, if not then I'll need to pull the clutch and replace it with something else.

I'll update this post with my findings and results for anyone else who has these issues in the future. Until then, anyone have similar issues?

Thanks,
TomK

 

I owned a clutch shop for 30 years and have had issues with Centerforce clutches in the past. Take the weights off. It's a little tough to get them off but not impossible. They use a little stronger diaphram than the stock unit, so you should be OK unless you have a lot of extra torque. The only time the weights come into play is at a higher RPM. They are supposed to apply extra pressure to the plate ah high RPM by centrifugal force. What that does is make the pedal harder to press. The additional torque capacity of the clutch should be taken care of by using the DF disk. Which is simply a stock clutch with a metallic or Fibertuff (kevlar mixture) facing on one side and an organic on the other. Any good clutch shop can build you one just like it for half the money. Another issue is do not use synthetic brake fluid in the clutch system. It will actually compress and reduce the slave cyl. travel.
Hope this helps a little.

 

Does anybody make a DOT4 brake fluid that's NOT synthetic?

 

It does help, thank you so much. The issue I have is that the prior owner also installed a big-black bellhousing that doesn't have a bottom cover (like the stocker), it's one piece...so to even get to the clutch, if removing the weights is possible with the clutch and driveline installed, I still need to drop the driveline.
I am hoping that the adjustable master from Tick does the trick...if not, then I'm on to another clutch for peace of mind.

 

Received the Tick adjustable master today...very nice piece.
Install for this weekend...hope it works.

 

Let us know your results. I got this clutch sitting in my garage ready to install. Very interested.

 

I've had zero issues with my CFDF with 15,000 miles on it so far.

 

i bet the tick fixes it. Seems to me once the master is adjusted out a bit the difference the weights make at high rpm wont be as significant. I have the 12" too and it engages about 1-2" off the floor and I have no problem at high rpm. In other words it appears to be something that will be fixed by further depresssion of the PP. Let us know

 

I think you mean silicone not synthetic.

 

That is my goal, as my clutch engages literally "from the floor"...it feels like it never really fully disengages, so a little more movement of the PP may just do it.

 

Same here, I have the 12", the 11" have the issues.

 

After an interesting install, and a bleed that seemed to take days...it worked.

The result in some detail - http://forums.corvetteforum.com/c5-t...post1572858245

 

its dumb that they put in the instructions to skip the gravity bleed if you have a remote bleeder....gravity bleeding would speed up the process of bleeding 100x....should be...gravity bleed and then use the remote bleeder to get the few remaining bubbles out this would have filled the master with fluid prior to pumping all that air through your whole system due to a dry master

 

What is gravity bleed? never heard that. well i never did bleeding on my vette except rangers turkey baster method, still on good stock clutch, but definetly help for future.