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I know this subject has been beaten to death in the past, but lots of us still have gear engagement problems.
I have a standard 3 finger McLeod clutch, pantera spinner, new slave and master from Roland Jaekel, new release bearing and new flywheel bronze bush
but only with the clutch fingers touching the release bearing without free play can I engage
first relatively easily.
I read today that the clutch pedal should be half an inch higher than the brake pedal. mine is not its level with the brake.

I must be doing something wrong? I also hear that a longer throw slave cyl is sometimes required. I also hear that it isn't required.

I hear that therapy may help a very confused old Git, Pantera refurber. Help welcome.
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I am just a “student” and have yet to have any real experience with this clutch , but looking forward to it.

From what I have gathered from my “engineering” point of view;

The OEM master cylinder is a 0.75” diameter with a 1.125” stroke. Thus about 0.5 cubic inches of fluid transfer

The OEM slave cylinder is a 1” diameter with a 1.625” stroke. With the 0.5ci from the MC going full stroke, the slave active stroke is only 0.63”.

The slave to ToB lever ratio is such that the total TOB travel is 0.46”. thus the clutch compression mercal spring, plus the initial over travel to touch fingers (0.06") and the over travel to ensure disengaged (0.04")must be less than that stroke

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  • clutch
Peter, there are constant-contact throwout bearings that are designed to have long life with the throwout bearing adjusted to always touch the clutch release fingers. The real problem is, the Pantera clutch mechanism was designed with barely-adequate clearances in the whole system when brand-new. Wear, tiny leaks, non-stock parts or even using soft flex-hoses that expand under pressure may cause clutch-drag.

FYI, the clutch pedal position is adjustable by slightly varying the master cylinder rod length up under the dash. This is NOT a fun job!
Posted previously:
quote:
FWIW, here’s a summary of how to adjust the clutch on the Pantera. Being used to automatic transmissions for decades, it was a new and complicated world that opened up to me when I bought a Pantera with a hydraulic clutch and especially how to adjust it. Having bought all the literature I soon found inconsistencies. I’ve read many sources including the Instruction Manual, the TSB, PanteraPlace and others. And they were quite different. I think now I finally understand how to do it, and if it can help others, below is the short simple (?) method I’ve used

First, the basics have to be right: A good master, slave, pipe and line. And a proper Pantera clutch, not just a Mustang clutch. Some recommends a long-throw slave, and that will make getting the right adjustment easier. But it’ll also increase clutch pedal effort, something you don’t want (except if you want to discourage the wife from driving Wink). And the fluid has to be free of air.

1. Master: pedal should be adjusted so at rest it’s between 0-½” closer to the driver than the brake pedal. Then test with a friend that with the pedal fully pressed down, there should be at least ½” gap to the firewall/carpet
2. Clutch axle arm: the almost vertical arm from the ZF to the slave rod end. Imagine a straight line from the clutch axle on the ZF up to where the clevis pin is. That line should be 90 degrees towards the slave. Ideally it should be 90 degrees when the clutch pedal is half pressed down. Any other angle will result in that the slave rod movement translates into less movement of the clutch axle. Maybe you should move it a notch? Also check that there’s free movement, when the clutch pedal is fully depressed, does the arm or the bolt/nut perhaps rub on the ZF? And get a proper size clevis pin, previous owner had just used a bolt that was 0.3mm less in diameter
3. Slave return bolt: Temporarily remove the spring. Use your hands or a tool to move the clutch axle arm rearwards, and feel for when it hits the resistance of the clutch. Should be easy to feel. While holding the arm in that position, turn the screw so that it almost touches the bracket, leaving a 2mm gap. This will ensure that a. there’s no wear on the clutch release bearing when the pedal is not pressed down, and b. that you get as much movement of the clutch as possible. Reinstall the spring
4. Slave rod: Some suggest that the rod is used to position the resting position of the clutch axle arm and that the return bolt should be thrown away. And some say this is not good, because the slave should not bottom out. I think the best is to use the return bolt as described in 3., and then adjust for almost maximum slave piston travel on the rod. Almost, so with no bottoming out. With the system at rest, take out the clevis pin and by hand press the slave rod all the way up in the slave. And then release 1mm. Do the holes now align so the clevis can be put back in? If not, adjust the length of the slave rod, so that they do

With all this done, you should have a clutch that neither slips nor grinds teeth. And of course you must press the clutch pedal all the way down every time. Happy shifting!
quote:
Originally posted by Bosswrench:
Peter, there are constant-contact throwout bearings that are designed to have long life with the throwout bearing adjusted to always touch the clutch release fingers. The real problem is, the Pantera clutch mechanism was designed with barely-adequate clearances in the whole system when brand-new. Wear, tiny leaks, non-stock parts or even using soft flex-hoses that expand under pressure may cause clutch-drag.

FYI, the clutch pedal position is adjustable by slightly varying the master cylinder rod length up under the dash. This is NOT a fun job!


Please look at the pic, I have removed the master cyl rod but it is mechanically impossible to adjust the rod to make the pedal any higher.

It is retained by the linkage, also with a bit too much adjustment the pedal can then attempt to PULL the rod instead of pushing it DOOOOOM sday is here.
To disengage the throw out bearing at rest adjust the trunnion shaft on the slave, if their is no pressure on the arm coming out of the trans and the throw out is still touching,is it making the clutch slip? If you drive a few hundred miles and still doesn't disengage at rest,the only thing I can think of is you have a mismatched disc. is it a Mcleod disc? I also want to let you know, I had trouble engaging 1st gear on my newly rebuilt ZF, I changed out the really expensive Lucas oil for the cheap O'reilly oil and the trans shifted much better and no issue with 1st.
Chris, I made the mistake of having my clutch disc relined, Knowing nothing about Pantera clutch systems the, I just assumed it would be OK. There were all sorts of problems and I removed the ZF and the "New" plate.
The plate I had fitted was so much different than an old but not worn Plate that had been used in a friends Pantera and I fitted it, things were much better in that I could get a gear again but still no play at the finger ends.
so no I don't have a McLeod plate
Goodroc, I have no wear in the shift linkage and gear selection was NEVER a problem before I removed the engine and fitted new clutch parts.

I do appreciate your comments though, I have to beat this thing.
BTW after looking at your Photo I would say that you should not have a problem to adjust that Clutch Pedal further up/back. At least 3-5mm on the Push Rod on the Master would be my guess. Give it a try!

And concerning the shift Linkage it might very well be slightly out of adjustment. Just how well does the Gear engage if you remove the shift Gate?

Looks nice with new Interior Trim ;-)
The ONLY sure way to determine 100% release of the clutch disc is to use feeler gauges and measure the clearance.

I can't remember exactly at this moment the differences in the requirements but the three finger requires less clearance than the diaphragm does.

I think it is .035" for the three finger and .045 for the diaphragm.

That's all that matters. Leave the clutch pedal alone. It winds up where it winds up.

The only significance to that is that at somewhere less than full travel you have full release.

Also consider that these nice thick plush floor mats have a very significant thickness to them and reduce the amount of travel your pedal has to release the clutch fully. All this issue could simply be that.

As BW says, everything is so freakin' tight with adjustment on the Pantera for clearance, a simple change like the disc thickness or a change to a disc with more Marcel can change everything.

The original Pantera disc had the Marcel removed to add clutch travel to make it work.

If there was an original mistake in the calculation for the necessary clutch travel then it was likely for Marcel.

It is also possible that the calculation was taken from the GT40 as a race car and it had no Marcel in the disc.

As far as how to adjust the Pantera clutch, block the pedal to the floor, then adjust the slave to give you the clearance with the feeler gauge installed.

The observation port in the bell is put there so you can do this procedure. In fact it is probably the only way to be sure the release clearance is right.

As BW also said, a ceramic throw out bearing is a great idea so that if it happens to be that you are riding a hair on the fingers because that's all the travel you can get, you won't eat up the face of the throwout bearing.

The tips of the fingers are already hardened for this.

You actually need to be really careful with the Centerforce that uses a diaphragm disc because those fingers are not sufficiently hardened to resist wear.

...and not to be argumentative Chris, that isn't my intent but I seem to remember the full new disc thickness as right around 3/8" or .375 to .380 with the micrometer WITH a full Marcel disc.

I don't have an "original" clutch disc here to measure but it would make sense to me that without Marcel it might be right what you said at around .280"?

In my young and wild days as opposed to my old and cranky ones, I seem to remember putting calipers on "worn out discs" and they were at around .320 to.325" left, so bottom line, there isn't a lot of material between full and empty on a disc.

For those who don't know. The wavy line that runs through the center of the disc (arrow pointing to it) is the Marcel spring. It helps push the clutch apart when releasing and was eliminated in the original factory installed disc to gain room for the clutch assembly height.

I don't think that I am having psychotic episodes right now, for one thing no naked waitresses are wiggling their 'goods' and trying to seduce me...but that may not be the determining factor...I don't know...I forgot? Razzer

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  • clutch_marcel
Hello David,

I have tried to find if this was correct in an earlier thread, and have sent pics to a couple of folk who I thought would have known but without a reply.

So I thank you very much indeed for pointing this mistake out, I took out the gearbox today, god it was cold out there, and found an anomaly with part of the clutch which I am going to fix.

But I will change the quadrant to face the correct way round.

Last question, for now.Is the clutch effort reduction system worth keeping, is the effort much reduced?
Thank you again.
quote:
Originally posted by PanteraDoug:
The ONLY sure way to determine 100% release of the clutch disc is to use feeler gauges and measure the clearance....I think it is .035" for the three finger and .045 for the diaphragm.
....
As BW says, everything is so freakin' tight with adjustment on the Pantera for clearance, a simple change like the disc thickness or a change to a disc with more Marcel can change everything....The original Pantera disc had the Marcel removed to add clutch travel to make it work.
....
and not to be argumentative Chris, that isn't my intent but I seem to remember the full new disc thickness as right around 3/8" or .375 to .380 with the micrometer WITH a full Marcel disc.

I don't have an "original" clutch disc here to measure but it would make sense to me that without Marcel it might be right what you said at around .280"?
...
For those who don't know. The wavy line that runs through the center of the disc (arrow pointing to it) is the Marcel spring. It helps push the clutch apart when releasing and was eliminated in the original factory installed disc to gain room for the clutch assembly height.
...


I would not think it is the "thickness" of the clutch that matters that, but the amount the marcel compresses when squeezed by the pressure plate. this small amount of compression becomes greater at the Tob due to the lever ratio of the fingers. thus that is the value I think the clutch maker should tell you.

as for wanting to have 0.040" clearance when fully disengaged, the lever ratio of the fingers will make the needed ToB travel even more. that is another value I think the clutch maker should provide.

I think I have seen a ratio of 6:1 being a norm, so out of the 0.46" ToB stroke available, subtract 0.240" ( 6 X 0.04) for full desingaged and the desired 0.1" intial travel of the slave when first depressing with would be 0.06" at the ToB, that only leaves 0.16" to decompress 0.025" worth of marcel

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  • clutch_marcel_r1

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