I recently installed a centerforce dual friction in my 69. When i first installed it i barley had enough room to adjust the linkage to ge the clutch to fully dissnengage, but the car drive fine with no problems for a while. Recently it feels like the linkage is binding and just today the clurth started to not fully dissengage. Is there a way to adjust this other than at the first part of the linkage, has anyone had simmilar problems.

 

I am having a similar problem with mine. But it did that with the clutch I had in before, not sure if it was stock or not. It engages very smooth when cold and gets bindy when hot. I found my fork geometry is off and that may have caused some issues with the pivot ball and fork connection. I can see guages on the bellhousing where the fork was digging in. I am going to replace the fork and use an adjustable pivot ball when I convet to a t-5 next year. I have cut some 6 inch strips of sheet metal and bent them to conform to the pivot ball so it acts as shim if you will. I currently have 4 shims in but am going to add 1 or 2 more since they seemed to have conformed to the pivot ball. The difference was amazing when I first put them in. It was sooooo smoooth! I used a zip tie around the fork to make sure they can't fall into the bellhousing area. Not sure if this fix is for you but check out the fork geometry to see if it is digging into the bellhousing.

 

Do an archive search on this subject, there are others with your problem. This was pretty recent and I think it was a quality problem, but not sure. A few folks just took 'em off and went GM again with no problems encountered.

 

I think the problem is you need an adjustable pivet ball.

CF tells you to adjust the ball x inches from the belhousing face.

I think that will solve both your problems. When I put my CF in, I could not get enough adjustment. Took trany out adjusted ball and have not touched since.

Terry

 

Yep, I had the same problem when I had a new Centerforce clutch (not dual friction) installed in my 68. A mechanic did it for me.

Just to be perfectly clear, my problem is I have to press the clutch pedal all the way to the floor to shift gears. I would prefer to press the pedal down only about halfway to the floor, but I have to mash it all the way down. When you go under the hood to adjust the clutch, the nut is already at the very end of the rod, so no further adjustment is possible.

The solution, as told to me by others (and mentioned above) is to put in either an adjustable pivot ball or the longer GM part. GM makes 2 different size clutch fork pivot ball studs. Now, I have also heard from somebody that the long one was too long, so perhaps the adjustable is the right answer. I still havent switched mine out because I am not that psyched to pull the trans. I'm sure it would help my 1/4 mile times tho!!! :) MJ


Here you go!! Check out my thread from Sep 2001 :) (Love this forum!!)
http://forums.corvetteforum.com/zerothread?id=158546




[Modified by MNJack, 3:50 PM 7/24/2002]

 

i would agree with all the suggestions above except for the part where you mentioned binding. something i learned from personal experience is there is a pivot bolt that bolts into the rearmost portion of the block to support your 'z-bar'. mine had begun to back out and was wobbling allowing me to side load it when i pushed in that heavy clutch. i didn't know this, mind you. of course, one day it snapped off clean at the block and i had no clutch at all. won't go into how i got it home but fortunately, since it was loose when it snapped i was able to tap out the threaded portion from the block and just replace the bolt. at least it's a very easy check. :chevy

 

I guess everything is different for everyone. I installed the Centerforce and the pivot ball measured and has worked great for over a year. Makes you wonder why these distances differ.

 

Dig out the orange piece of paper in the clutch box that came with the clutch. It gives the specific dimensions for the pivot ball.

Until you set it at that height, it will never work right.

There are basically two pivots from GM. The tall one was typically for cars with diaphragm clutches. They are much flatter and the arm needs to be moved "forward" to get it close enough to work right. The short one was for cars with "raised diaphragm" (stronger HP type) and Borg and Beck type clutches. They are taller and the arm has to be moved back toward the trans with the shorter pivot.

The Centerforce DF is usually somewhere in between. Depending on your bellhousing or scattershield, it oftentimes requires an adjustable ball to make it work. On mine with a McLeod scattershield and block plate, the short was too short, and the long was just barely too long. I used an adj. one.

What your looking for is that when the clutch is engaged (pedal not depressed), the throwout arm is pointing straight out from the bellhousing or slightly forward toward the front of the car. You DO NOT want it angled at all toward the rear.

There are several different length arms out there for Vette's. I tried a shorter one once on my '67 to speed up the ratio of the linkage, but it hit the floorboard. Like you, I like it to release quickly without a lot of pedal travel.

You also need to look at the inside of the car where the linkage attaches to the pedal. ANY wear there will drastically eat up pedal travel. Many times it requires replacement or welding up and redrilling the hole.

Another trick, is to redrill your crosshaft about 1" lower on the upper arm where the pedal linkage attaches to it. This will speed up release and makes a big difference. It's a little harder to push since you give up some leverage, but the CF is pretty easy to push anyway. Be prepared with GOOD drill bits or use mill like I had to do to drill that linkage. It's tough!

You must maintain plenty of free travel with the CF. The weights actually pull outward on the fingers at high rpm and you lose a little freeplay. If you have it too tight, the fingers push against the throwout bearing and if you are making power it will slip.

The CF dual friction is a great clutch, but you must install it correctly. I've had mine behind the 427 running low 11's with slicks for over 3 years and now it's been behind the 540 for 1 1/2 years. Never a problem with the clutch, but it did manage to break a few rear end parts!. No slips and I happen to have the body back off the frame right now and recently looked at it. It still looks brand new. Perfect!


Jim

 

Running a Centerforce DF with no problems. In fact I am very pleased with it's performance as long as my rear end holds up! :smash:

 

Jim has the best explanation.

I had to use a new pivot with my stock bellhousing to get the right distance. I now have 5000+ miles on the DF with no problems. That distance from block face to pivot ball is critical. It also needs to be adjusted if you flywheel is non-stock or has been resurfaced. The orange sheet in the clutch box has all the info.

 

Can anyone give me the info thats on this sheet. I cant find mine and i cant find the info on the centerforce website. Thanks for the help.[

QUOTE]
The orange sheet in the clutch box has all the info.[/QUOTE]

 

One more trick, I cut the horizontal linkage arm and welded in a 1" piece of steel to it, the nut was at the end and I had no more adjustment left. This gave me 1" more to adjust with. I had to dig into the fiberglass a little on the floor board, but it finally worked. I have had no problems since.

 

I had a similar problem with my CenterForce and it took some time to figure out what was wrong. When all was said and done, almost all of the freeplay was removed from the pedal and now things work fine. The clutch is smooth, there is enough space when the pedal is out and it has been checked and double checked. Instead of one inch freeplay, there is now about 1/8" .....but that is enough. No binding, squealing, sticking.....works just fine!

 

I've been running this clutch for years as matter of fact it's my second in the past 6 years. It has pulled many 12 second 1/4 miles without any problems. Geometry is very important. There was an article in a hot rod magazine that gave all the details. If you are still having problems I can dig out. :cheers:

 

Had the same problem when I put the DF in mine. I put the longer ball stud in and no problem. GM also has a longer throw out bearing,about 3/4 in. longer. It was in old pickups late 50s early 60s auto zone had it in one of there books. At the time they had the stud and had to order the bearing so the stud went in!! If I had to do over would order the bearing to get the geomerty in line a little better. Just the way it worked out for me.

Jon

 

Another possibility is throw-out bearing bind on the trans nose where it slides back and forth. because of the design, it wears an angled wear spot in the underside of the bearing retainer and will start to bind as the clutch wears. replacing the retainer fixes it. Better deal is to use a hydraulic throw-out bearing and lose the fork, but it would require engineering a master cylinder mount.

Hans

 

That trans nose must expand because my clutch is very smooth until the trans ges hot then it gets bindy. I unhooked the rod from the clutch fork on everything in front of it is very loose and easy to move. I fixed my geometry which reduced the binding but it still happens when hot.