clutch adjustment

1. You absolutely should install a return spring so that the clutch fork does not ride on the throw out bearing, or it will prematurely fail.

2. The adjusting nut on the clutch arm should be adjusted to the point you can just feel play i.e. it is not constantly riding on the throwout bearing.

Definitely install the return spring. Adjust the free play at the slave cylinder adjusting screw to .102". Use a #38 drill (.1015") or a 7/64 drill (.1094").

JB,

I am currently doing this too. Where do you check the play?

Carbo,

Adjustment is at the slave cylinder. Free play is adjusted per the pic on the right. Pic on the left is for the slave cylinder push rod.

Thanks, that looks like what I need.

Carbo

Step-by-step instructions are here at Pantera Place http://www.panteraplace.com/page124.htm

Mike

We just got our 1974 pantera restored and we're having some issues with the clutch setup.

When the car is cold I have no problems shifting through the gears.
I get about 3/8" of movement from the resting position (the space shown in fig. 16 from jb1490's post above) when the clutch pedal is fully depressed.
Once it's running for a bit and hot, I don't seem to get enough travel from the slave cylinder push rod. I'll lose about 1/8" of movement.
Does anyone know what the problem could be here?

Have you checked for air in the clutch hydraulic system? Air in the system will expand when hot and push fluid back into the master cyl res resulting in less movement of the slave piston when the clutch pedal is depressed.

Yea, we've bled the system a few times. Just did so now. We'll take it for a spin now.
I'll post a result shortly.

We bled the system...tiny amount of air, almost nothing.
Took it out for a short cruise, same problem as before.
After it heats up we get less movement at the slave cylinder push rod.

I do notice a good amount of movement in the hose from the master to the slave cylinder.
If the hose is heating up and becoming pliable, could this be causing the loss in movement at the slave?

# 6579 Do you get air out of the system when
you bleed it? Have the clutch master and or
slave cylinders been replaced? Are you bleeding
the system at the master or slave?
Have correct fluid in system?
TOM at T.J.s does great work. Has done
some work on my car as well.
JOHN

quote:

Originally posted by No. 6579:
We bled the system...tiny amount of air, almost nothing.
Took it out for a short cruise, same problem as before.
After it heats up we get less movement at the slave cylinder push rod.

I do notice a good amount of movement in the hose from the master to the slave cylinder.
If the hose is heating up and becoming pliable, could this be causing the loss in movement at the slave?

The line from the master to the slave area is metal with a very hard red plastic section near the slave. Sometimes people replace the red plastic with a braded steel line.

Mike

We bled the system at the slave. I'm not sure how you bleed at the master. There was the slightest amount of air when bled last night.
We're using DOT 3 brake fluid. Both the master and slave are new, from Precision Pro-Formance.

The line from the master is stainless then about a 4 ft section of hose to the slave, not sure what type of hose.
Again, there is a significant amount of movement in the hose when the clutch pedal is depressed.

quote:

not sure what type of hose

Can you post a pic of the hose?

How much free play do you have at the slave cyl when cold?
Does the free play change when hot?

The hose is an Aeroquip FC332-04. 1/4 " hose 250 PSI rating.

We've had some trouble feeling the free play. We've read the adjustment instructions on the pantera place site, but haven't been able to feel any kind of free play. With our current setup it seems almost impossible to move the clutch arm at the tranny by hand.

We've adjusted the slave cylinder push rod shorter and then were able to feel maybe a little bit of play, but then we weren't getting enough movement to fully disengage the clutch.

I suspect that the Aeroquip hose may be the problem. I don't think that the pressure rating is high enough. I'm surprised that whoever installed the ss hard line didn't also install the ss braided flex line to the slave cyl. You can order the ss braided flex line from one of the Pantera vendors or have one made up locally.

As a temporary test, you could get a length (or two) of 1/4" steel brake line from the local auto parts to replace the Aeroquip hose. You will need to change the fittings and reflare the tubing ends. Copper tubing will also work, as this is only temporary.

If the hose is the problem, what PSI rating hose should be used?

I'm not sure what the normal pressure in the system is, but I would guess around 450 to 500 PSI. It depends upon the ratio of the master cyl and slave cyl bores, the pressure plate spring rate, and how quickly you depress (or stomp) the clutch pedal.

The Aeroquip FC332-04 hose has a fair amount of elasticity, has a max 250 PSI rating (you knew that), has a max temp of 300*F, and is not approved for impact hydraulic applications. Stomping the clutch during a fast shift could be construed as an impact application (kind of). If it were my car, I would get rid of the rubber hose and use the ss braided teflon hose. Besides, the ss line looks much better than a hose (even if the hose is blue!?) IMHO.

This all assumes (fatal error) that the clutch master and slave are functioning properly and free of air.

Other possibilities would be if the clutch pedal is not returning fully (broken spring?), the clutch master cyl push rod is too long, or the master cyl is by-passing.

I'll add my two cents. I was having a problem with not enough disengangement, grinding going into reverse and trouble going into first, etc. All this occured when everything was warm. I monkeyed with the slave, bled it, adjusted it, checked free play, etc. Finally, I got fed up with no progress and decided to adjust the eye bolt out far enough that I was sure to get plenty of disengagement. It worked. I now get plenty of disengagement and it still hooks up fine. I am sure I will get flamed for this, but everyone on this forum seems to worry more about "free play" than disengagement. We all seem to be grinding reverse and not shifting correctly in an effort to save the throw-out bearing. I say, go in the opposite direction. Pull the rod out of the slave and give yourself more marging on the disengagement side. The stock rod can be adjusted to give you more than enough disengagement. Just play with it until everything works correctly.

Oh, and the plastic hose comes in handy when bleeding the system. It allows you to see when there are no more air bubbles. Plastics are typically a no no in hydraulics, but in this case there should be no problem. Unlike a braking system, there is no progressively higher pressure in a hydraulic clutch. Once it is to the floor, it won't go any further or generate anymore pressure. The pressure in the system is the minimum amount it takes to disengage the clutch. All the pressure the system will ever see is due to the force generated by the throw out bearing against the clutch fingers. Think about it.

Joe6pack,

I respect your opinion but tonight I'm taking my ZF out due to, I believe premature t-o-bearing failure. I just ordered another HD bearing from PI. The last one lasted about 1000K, 500 on the old engine then 500 on the new one. The first time I jumbed on the new engine the clutch slipped so I adjusted the bearing out to give more free play and engagement. That worked for a while and things were great but now I hear a bearing noise at higher rpm's 5800 to 6000. If I depress the clutch peddle a bit the noise changes a bit. I believe that this is because I had the t-o-bearing too close to the pressure plate. I'll let you know what I find. I'm just giving you a heads up so you don't have the same premature of the bearing.

Sorry Jo6pack, I mean John. Just saw your name at the end of your post...

Someday I’m going to do a diagram to help owners understand this adjustment. It is really, really simple. But for now if you follow the adjustment instructions the clutch should work perfectly using stock de Tomaso parts. If it does not work you have a leaking master, air in the system or a bad or wrong clutch cover/plate.

Mike

John,
We have tried adjusting the slave cylinder push rod to it's longest length, but it was then almost impossible to hook the system back up. We could barely get the clevis pin through the eye hole of the rod.
When we eventually got it all hooked up, we didn't have the grinding problem, but we were not getting enough clutch engagement.

As I left the car on Sunday, I had it hooked up to where I could start it up and easily get into all forward gears with no problem, even reverse. But again, once the car gets warmed up I lose movement at the slave.

If this were a leaking master/slave wouldn't the problem persist from the start, rather than after it heats up?

Is your hydraulic fluid maybe getting too hot and loosing it's compression properties? Don't know just a thought, I'm not a chemical engineer.

That shouldn't be the problem, I'm using DOT 3 break fluid.

John Kazlo,
Do you know of any mechanics that have knowledge of the clutch system in your area?
I live close to Holbrook and haven't been able to find anyone with any real knowledge/experience besides TJ's.

All - Yes, it was difficult to get the pin in. And, I was worried that the slave would not compress enough to allow the throw-out bearing to move off of the clutch fingers. However, I was pleasantly suprised at how much the slave compressed. I confess that this is a new adjustment for me and I will let you know how it goes. I just got fed up with the grinding.

No. 6579 - You say you have a measureable loss of throw at temperature. It definitely sounds like there may still be air in the system. Although it is usually tempting to suspect parts, I find that most problems are adjustment related.

I honestly think these problems (and we seem to have a lot of them) occur with new clutches. This is when the adjustment between free play and disengagement is most critical. The slave cylinders only have so much throw. Once we get a little wear on the clutches, things should straighten out (I hope).

Not to disagree too much with the free play crowd, I think an acceptable way to set up the clutch would be to adjust until you get acceptable shifting performance across all temperature ranges. If, at that time, the throw-out bearing is contacting the fingers in an unacceptable way, then you have another problem that cannot be adjusted away.

I'll try bleeding the system again this weekend after I get the car warmed up, and see how that goes.

Also, when you start to depress the clutch, should the slave cylinder push rod start moving immediately? or is there a delay?
Does this affect shifting/disengagement?

Joe6pack - How has that adjustment worked out?

quote:

Also, when you start to depress the clutch, should the slave cylinder push rod start moving immediately? or is there a delay?

The clutch pedal should have some free play also. It varies from car to car, but is usually around 1/2" to 3/4". Then the slave cyl push rod will start to move.

So far, so good. It's never shifted better. Before, if I moved the clutch pedal off the floor a tiny amount, the clutch hooked up. Now, it hooks up about halfway through the travel range of the pedal. This seems more reasonable. Also, I can now go into reverse with no grinding. I still can't shift into first every time while sitting still. If I am rolling a little and downshift to first it is no problem. Overall, I am happy.

I'll let you know if there are any problems.

Can I ask a stupid question?

On the tech service bulletin the distance for the rod is 3.07" - 3.09". If this is the correct length the rod should be then why is it adjustable? I just R&R'd the ZF to replace the to-bearing yesterday but have not had a chance to test it yet. The old one did not look too bad so I'm thinking that it may not have been the source of the noise. I'll see later today but I just wanted to go over the adjustment one more time and noticed the rod length post.

The rod adjustment sets the position of the piston in the slave cylinder so it is in the working area. Too long and the piston will bottom in the top of the cylinder not allowing the free play to be set. When the clutch arm is on the correct spline on the clutch shaft it should all fit together so the only adjustment needed is the free play. The home position of the throwout bearing is controlled by the free play stop bolt. Because the slave is filled with hydraulic fluid it automatically adjust so that wherever the free play stop is positioned so the slave piston will move in sync with the master piston like a direct connection. Once you can grasp the concept of how it works and adjusted it is quite simple.

Things I’ve seen that messed up the clutch system:

1. Bad flywheel surface
2. Wrong clutch disc
3. Wrong clutch cover
4. Damaged or wrong throwout bearing
5. Throwout bearing retaining spring installed incorrectly
6. Front bearing in ZF slid back from case
7. Binding clutch shaft
8. Clutch arm on wrong spline
9. Broken clutch arm
10. Rod adjustment wrong
11. Free play set wrong
12. Missing free play stop
13. Leaking slave
14. Air in system
15. Master bypassing
16. Master leaking
17. Master push rod out of adjustment (too much free play/not enough
18. Clutch pedal set too low or too high
19. Oil on clutch plate

Mike

Thanks Mike,

I looked at your website and I believe that someone has changed the slave cyl at one time. Mine is a dark blue and appears to be aluminum and the rod does not look like yours. It may be long throw. I think that I have the concept you described except that when you said that slave piston and the master piston move in sync which makes sence. So if you have a long throw slave you would think that the total movement of the rod can only be as long as the master piston. Then how can you ever get a longer throw that whatever the master piston is? Oh this is getting to mechanical now, I'm civil and structural.. Thanks Mike

quote:

slave piston and the master piston move in sync which makes sence.

Mike (74LQQKR),

The master and slave pistons are different diameters, so they travel at different rates (the smaller diameter piston would travel farther). If they were of the same diameters, then they would travel at the same rate (distance). Clear as mud??

John

Yep, clear as mud ..

74LQQKR
Try this site for basics on hydraulics. Stop, I repeat, stop, as soon as you have the basics otherwise you'll get a headache.

http://www.pirate4x4.com/tech/...Steering/index1.html

Glenn

Boy Glenn,

What a great site. Every thing you would ever want to know about hydraulics, at least for me. Thanks for the link, brings back some old classes...

Mike,
We're still having problems shifting. We're not getting enough disengagement even after adjusting for free play. We've shortened the slave push rod and slowly lengthened it after each failed attempt to shift and it seems like we get the same amount of throw no matter the length of the slave rod.

Could it be an adjustment at the master?

How do you adjust the master push rod?
I believe we've got a clutch pedal reduction kit if that makes a difference.

quote:

Could it be an adjustment at the master?

I had suggested checking this previously in this thread.

The master push rod is threaded into a clevis yoke, and is secured with a jamb nut. It is very difficult to get to, but it can be done (painfully) from under the dash. If you have the effort reduction kit installed, make sure that you don't adjust the push rod too long. This will cause the clutch pedal to be harder to depress (initially), or not depress at all.

I still think that the Aeroquip hose may have too much "flex". IMHO.

I forgot to mention something important in my previous posts. We had the car running nicely for quite some time, but coming back from about a 75 mile cruise the hose to the slave cylinder slipped off the fitting at the slave.
This shot fliud all over the engine bay doing a number on the paint.
I was able to get the hose back onto the fitting with a hose clamp to keep it from slipping off again. Then I drove the car back to the garage (about 20 miles).
At this point the car seemed to be running fine. Then all the issues started. Trouble with disengagement. I also noticed a dark oily spot under the car on the garage floor. I thought it was just some oil from the tranny, but now I'm curious if it's related to the hose coming off the fitting.

I have since bled the system several times and still do not get enough disengagement.

Any opinions.