clutch /

[John 550]

I was wondering if there is a difference in travel needed on a 2800 lb pressure plate compared to a lighter one ? Does a heavy Duty pressure plate need more travel ?
On a friends era car , with a 428 , I am having an issue with needing more travel to dissengagee the clutch . 2nd owner The clutch does not slip , 6000 miles . Tires like new ( clames to have been driven easy ) Looking where the clutch fork goes , the condition on clutch look good .
We spent two saterdays on bleeding fluid , adjusting the master / slave linkage adjustments .The 3rd saterday we spent replacing the master cylinder / slave cylinder , still no improvement . The linkage needed to be pre loadere to get in to dissengage . This I have been told is not common .

I want to find out what I can before changing the clutch to a standered one . I do not know to much about the clutch other than it is a 2800 lb and it is a red-ish pink color


Thank you !

[John 550]

should I move this to shop Talk ?

[Tom Wells]

Hello John 550,

No direct answers but here's a couple suggestions that should get you your answer:

Go to the "ERA---Speak with Bob Putnam" forum and ask Bob. He does answer quite well!

Or go to the online ERA manual here:

ERA 427 manual (PDF)

and look at page 89 to begin with.

Hope this helps,

Tom

[John 550]

Thanks , I had talked to Bob some time back on this , but it is not the car as I have now replaced the parts . Must be the pressure plate .

[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.
__________________________________________________ ________________________________________
• 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.