US300hp

I recently rebuilt my 69 corvette engine and installed a new clutch assembly. The car is totally stock. I have driven the car but the clutch pedal needs to be put to the floor boards to shift gears. It then grabs immediately when you release the pedal even one inch. Normally I would say the linkage screws need to be readjusted, but it is already at the end of the travel. In other words no more adjustment is possible. The fork, z bar, and pedal all seem to be correct when looking at an assembly manual. What could be the problem?? Any real pictures or measurements of the linkage would be helpful. I've already looked in Paragon and Dr rebuild and everything looks correct, I would really like to see a Real car picture not just a drawing. THANKS!!!!!

pws69

Common problem, especially with Centerforce Dual Friction clutches. You need a different pivot ball for the clutch fork. The geometry is incorrect - the pivot point is too low (pivot ball shaft is too short). Most replace the stock pivot ball with an adjustable one - Summit carries them. There are MANY threads here on this very subject.

Gordonm

Did you install a new throwout bearing? Some of the throwout bearings are a little different in height. Is the clucth stock or aftermarket?

Here is my setup with a Speed Direct linkage setup. I run a Centerforce with an adjustable ball and a Lakewood scattershield.

...Roger...

Make sure your not loosing disengagement action with some worn items.If "everything" has just a little wear on it it can add up to enough to create the problem you are having.Is your clutch pedal under the dash wobbly,are all the pivot points slightly sloppy?Check both ends of the Zbar,make sure the pivot in the block is not wobbly.How much padding do you have under your floor mat?

69/03vette

Had to go with the Long pivot ball on my 69. PIA because you have to take everything back apart.

AzMotorhead

Another reason to not use a centerforce clutch.
I just did a clutch in a 66 this weekend and used a Mcleod clutch and Linkage from Speed Direct. Sweet & smooth clutch operation now

dmaaero

Mr gasket sells a longer clutch adjustment rod, does not look near as nice as Gordonm"s but looks more like the original just longer.

Surfer69

TO bearings could either be 2.5 or 2.25. Original 69 uses short one. Most clutch packages will give you the 2.5 so make sure you used the correct one. Pivot stud is also an issue as stated above. Either one you still are looking at yanking the tranny.

I had to yank tranny 3 times before I got my adjustable pivot ball correct and still is just barely working correct. Change flywheel thickness and clutch assemblies and you have to start from scratch trial and error.

Some new clutch linkage kits people are using that may give you more adjustment.

US300hp

Thanks for all the help. I installed a Zoom Performance clutch set with a new throw out bearing but I didn't really notice any difference in the thickness. The pivot ball I left in, I believe its stock. I would really perfer NOT to take the whole tranny out again so I'll probably go with the new likage. My pedal is a little wobbly so I'll check that too. Thanks guys!!

Ironcross

Corvettes correctly use the short TO bearing.

fly1977

I just went through this with my 69 and someone had put the wrong clutch fork in ,Had to pull the tranny, but the right fork fixed it . Good luck

69ttop

I had a similar problem. I bought a delco clutch kit because I didn't want any problems. Well after I installed the clutch the linkage geometry was off. the fork was up against the bell housing. Because I was working with a rolling frame troubleshooting was a bit easier. I put the new and old pressure plates on a flat surface and found the fingers on the new pp were 1/8 inch higher than the old GM pp which was enough to effect the linkage geometry. the fix was to install a adjustable pivot and adjust it
shorter. I don't like jury rigging anything but I had the clutch and flywheel
assembly balanced. from what I understand after market adj. pivots don't last. my original pp was a stock chev clutch that I installed 35 years ago with no problems. this could be your problem too.
by the way the delco clutch was made in korea.

mysixtynine

It gets more fun when you use a bellhousing with a block saver.

My quicktime bell ball stud was just a little too short as it was 6 3/8 deep compared to the 621 that was 6 1/4 deep.

I had to use a GM p/n 3790556 long 1.680 ball stud. It isn't perfect as it puts the clutch fork very close to the opening of the bell but it still has room to fully pull the throw out bearing away from the pressure plate fingers.

I am also running a tko600 and their 600hp dual friction clutch.

NMT1957

WOW I'm glad I just read this. I just put my tranny on my motor and getting ready to put it in the chassis. The body is off so it's an easy install. I think I really need to look into this before I put it in. Anyway of checking these dimensions before installing??? I have the motor and tranny sitting on the stand ready to go in. Now would be the time to deal with this issue. Can I measure the position of the clutch fork as it sits now to know if it will disengage properly.

NMT1957

I'm using a Centerforce Dual Friction Centrifugal Clutch. Its on a 1969 427/400.

wzschirnt

If it is "all stock", then the bottom clutch rod - from the z-bar to the fork - is not adjustable. After-market clutches sometimes have thicker material for the clutch disk.

Use an adjustable bottom clutch rod (Mr. Gasket, Moroso, etc sell them). Not 'stock' but it will make it work.

Something in the back of my mind tells me that I once put the z-bar in facing backwards that made adjustment really tough.

Good luck.

walt

NMT1957

Im thinking the best thing I can do at this point is to take out the Centerforce Clutch and install a stock clutch while its still out of the car. I really dont want to take it out later. I cant think of any way of testing the travel on the clutch pedal until the body is back on and i can actually push the pedal. Looks like Ill be selling a Centerforce clutch with 0 revolutions on it.

fly1977

Probally a good Idea, I know for sure with the stock clutch,pressure plate and release bearing from Paragon and the stock clutch fork and linkage and Z bar it works like a dream with lots of adjustment left. My car is 100% stock and I plan on keeping it that way.To each's own.CB