[DeTomaso] Help needed with clutch slave

Fri May 8 10:40:49 EDT 2009

Hi Mike, thanks for the advice, here are a couple more observations:

I think it's the pedal.  It feels like nothing is engaging until the pedal has been pushed about an inch down, then it seems as if all the action happens after that.

> >

>>>>That means that for the first inch of pedal travel, you're not actually releasing the clutch.   The clutch fork inside the bellhousing is just swinging through free space, doing nothing, until it finally touches the throwout bearing which then starts to release the clutch.   You have adjusted the pushrod on the slave cylinder much, much too short.

When I installed the slave it had no fluid, so I was able to easily push the piston completely up inside.  If it were longer, the only way I could have gotten it attached to the arm with it all the way compressed would be to have moved the arm further down on the spline.  As it is now, the piston is fully retracted when the clutch pedal is out, and it extends all the way until the arm can't rotate any further down, in other words, when the pedal is depressed, it appears the piston is extending as far as the transmission will let it. 

>I'm afraid I don't understand.  If I turn the screw to begin pulling out the piston, that would be like pushing the pedal part way down, and isn't that partially engaging the clutch?  I've heard that's a bad thing to do.

>>>This presumes that your pushrod was properly adjusted.   You're looking for a certain overall length of the piston/pushrod combination such that the face of the piston in the slave cylinder is as far up into the slave cylinder bore as possible As I mentioned above, without fluid that was easy to do, and I did , and the fingers of the clutch fork are almost (but not quite) touching the throwout bearing  Again, I don't know what the fingers or bearing look like to see if they are touching.   The factory specification is just a hair over three inches for the overall pushrod length, but that is for a stock slave, and stock clutch.   Since you have all aftermarket components now, you have to determine the correct distance by feel (although it will probably be something close to that).

Disconnect the spring from the clutch arm.   Remove the pin connecting the pushrod to the clutch arm.   Remove the bottom snap ring holding the slave cylinder in its bracket, and slide it up an inch or two to get it out of the way.

You can now easily move the clutch arm by hand There's no way I can move the arm by hand.  I called another Pantera owner when I first started working on the thing telling him I couldn't more the arm (I wanted to check the full arc of the arm) and he said it didn't surprise him, and I wouldn't be able to move the arm by hand due to the massive resistance.  He said that's why it takes a hydrualic cylinder to accomplish moving the arm.   You will easily feel where the fingers of the clutch fork touch the throwout bearing   But I don't know what that feels like.  Feelings, whoa whoa whoa feelings....   Back it off a hair; that's now the target location when everything is put back together.

Lengthen the pushrod whatever amount you deem necessary If I do that, it only means I'll have to take the arm off and move it down further on the splined post sitcking out of the zf.  This will change the angle of the arm to a more horizontal position, and it seems to me that will decrease the leverage the arm has now and make the slave work harder (and after all, slavery is already illegal...) (your first guess) and then slide the slave back down, reconnect it to the clutch arm, and secure the bottom snap ring.   Chances are that it will be somewhat difficult to slide the slave back into position, because the piston will naturally want to extend, and you'll be compressing it as you're sliding the slave down.

By trial and error, you should be able to adjust the length of the pushrod so that when the piston is almost fully compressed, the clutch fork will be just slightly off the throwout bearing.   It's a good idea to leave just a small amount of space inside the slave cylinder It seems to me that could be accomplished by using the set screw; by turning it so it hits the plate and pushes the arm slightly outward, that would allow the pistion to start extending just a bit. , to allow for clutch wear.   (As the clutch disc wears thinner, the fingers on the clutch will 'grow' rearward, and there needs to be a little free space in the slave cylinder to account for this, or else the fingers on the clutch fork will start resting on the throwout bearing, burning it up and possibly causing the clutch to slip).

When you first step on the clutch pedal at this point, there should be relatively little motion at the clutch arm, and perhaps a half-inch of free motion at the pedal, before you feel a marked difference in your foot and the clutch begins to release  This is the odd part--even though the piston is all the way in, there is still that inch or so of pedal travel before anything happens.  Could it be there is still air in the system?  Is that what it would feel like?.   This ensures that you are getting the most out of the available pedal travel, using almost all of it to actually control the clutch.

You don't want the fingers to be touching all the time, because the throwout bearing will burn up and the clutch may slip.  I certainly wouldn't want to burn my fingers--but as I said, Im not sure where to look to see if that is happening.  While putting things back together after installing the new engine (with tons of help from a bunch of PNW club members, which was amazing) I decided to use a wire wheel to see how much skin I could remove from my left wrist.  Turns out it's alot.

Does that all make sense?   It sure sounds confusing to me....:>)  I appreciate all your help--and even more your patience!  The only good thing about all this is that I am slowly learning things.  For example, a year ago there is no way I would have even attempted this.  By the time I'm finished (which as you can see, may take a while!), I will have one more Pantera issue I will know how to address.  Thank you!

Mike

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