clutch /

[Cobra75]

Seems like you're not alone with this issue. I have been dealing with this for over a year and only solved it by taking out the slack on the slave preload.

Here's a copy of the previous posts that have talked about this issue:
•I believe I have my clutch problem solved. My Unique came with a 3/4" master and So. Auto put a 1" slave on my Bell housing. After talking to Wilwood and a bunch of other folks, I was convinced that the master should be no more than an 1/8"smaller than the slave and mine was a 1/4" smaller. If you go with an equal size master and slave, the peddle effort will be too high.

This weekend my Wilwood 7/8" master came in and, after installing it, my clutch now works flawlessly. I obviously had a mismatched master and slave cylinder and the 3/4" master wasn't providing enough fluid to the slave to get full slave travel. Now when the wheels are off the ground and the clutch is depressed, the tires don't rotate and I can reach back and turn them by hand. It goes into reverse now without grinding or having to shut the engine off first.

•Bleed the clutch with the back of the car significantly higher than the front.

If there is a return spring on the throwout lever, remove it.

Without pressure on the clutch pedal, adjust the threaded link between the slave and the throwout arm so that you can push the link into the slave about 1/4" (with the throwout arm gently pushed toward the back).

You should get 5/8"-3/4" throw at the throwout arm when you push the clutch pedal all the way to the floor.

If the clutch doesn't fully disengage, you may have to raise the clutch pedal by lengthening the link between the master cylinder and the cross-shaft arm. If you can't get adequate movement then, a larger master cylinder may be needed, but we find that they rarely needed on a big block.
Bob Putnam-E.R.A.
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• Finally discovered the problem. Mine had a 3/4 inch master cylinder and a 1 inch slave cylinder. There just wasn't enough fluid being pushed from the 3/4 master to the 1" slave to move the slave cylinder far enough to get a correct adjustment. Do the hydraulics math and you'll quickly see the problem.

I replaced the 3/4 Wilwood master with a 7/8 inch Wilwood master and it solved the problem. The part number from Summit Racing is Wilwood 260-6765. If you want to see what it looks like go to http://www.wilwood.com/ Very easy to change.

You can also do a bunch more work and change the slave cylinder to a 7/8" slave, but you'll have to fabricate a new bracket to hold the 7/8 slave. Your master cylinder must be 1/8 inch smaller than your slave or it will never adjust correctly. If the master and slave are the same size (i.e. both are 1"), the peddle pressure will be too hard to push comfortably. If the master is more than 1/8 inch smaller than the slave, it can't move enough fluid to disengage the clutch completely.

• I believe I have my clutch problem solved. My Unique came with a 3/4" master and So. Auto put a 1" slave on my Bell housing. After talking to Wilwood and a bunch of other folks, I was convinced that the master should be no more than an 1/8"smaller than the slave and mine was a 1/4" smaller. If you go with an equal size master and slave, the peddle effort will be too high.