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118 replies

Clutch adjustment?

P peterfenlonMember
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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jfb05177jfb05177Member
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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bosswrenchbosswrenchMember
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!
noquarternoquarterMember
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!
P peterfenlonMember
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.
panterachrispanterachrisMember
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.
P peterfenlonMember
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.
goodrocgoodrocMember
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 ;-)
panteradougpanteradougMember
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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P peterfenlonMember
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.
jfb05177jfb05177Member
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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bosswrenchbosswrenchMember
Step 1: have a friend absolutely mat the clutch pedal from inside the car. Moving the floor mat from under the pedal may be necessary to get ANY clearance from Step 2.
Step 2: insert a flat-shim feeler gauge between the flywheel and clutch disc through the ventilation/inspection hole in the bellhousing.
Step 3- read the max thickness of gauge that can be easily inserted without force.

Note that doing this check will un-compress any marcel. I will be surprised if anyone finds as much as 0.040" of clearance by doing this. That also means that each side of the free-floating clutch disc only gets 1/2 of whatever clearance you find. So- best results of 0.040" actually gives only 0.020" between the flywheel & clutch disc, and another 0.020" between the disc and clutch surface. That much clearance is marginally OK but any less causes drag on one or the other spinning surfaces, which wears the ZF synchronizers and eventually causes grinding when going into gears. Less clearance means more clutch-drag and wear.

Note also that doing the above clearance check means nothing if you do NOT fully mat the clutch pedal with each shift, in your everyday driving. Most people including me do not, and synchro drag is the results of getting in a hurry with your shifts. Synchro replacement costs will eventually cause severe wallet-pain to most owners.
panteradougpanteradougMember
Keep the faith. I got .050" clearance, so it can be done.

Also the flywheel that you use figures in to this also. You can pick up probably .010" by resurfacing it. Even a new one.

The Marcel was reduced for this reason, i.e., minimum required clearances. They picked up maybe, .030" by doing so.


Everyone with a Pantera NEEDS a Pantera SPECIFIC clutch assembly. Modify a Mustang unit at your own risk?

It is specific to a Pantera. It is minimally a generic unit. How much were new syncros? $600 or was that $900 each?
Last edited by panteradoug
bosswrenchbosswrenchMember
Depends on who actually does the work. If you order the parts after pulling your ZF and do a tear-down to determine what wore out- the synchro assembly, the gear cone which requires full replacement of that gear and maybe the mating gear as well, or all of the above, and your assessment is correct & you reassemble it yourself correctly, is one price.

Or crate the 155-lb gearbox as befits a $6000 assembly and ship it to an overhaul facility, synchro R&R done this way can run several thousands of dollars and several months down-time.

Also realize that all new ZF parts including gaskets only come from RBT Transmissions and everyone pays full retail for them. Overhauls therefore all have the same parts costs so any variation comes from cheaper labor rates or cannibalized used parts recycled into your gearbox. Nothing wrong with that except used parts obviously won't last as long as new ones.... Some gasket dimensions are critical, too.

Last bill I saw (a dozen years ago) including shipping to RBT, tear-down, inspection and reassembly with a few new gaskets and only an inexpensive thrust washer replaced- no synchro required due to a mis-diagnosed noise- then return shipping, was for $1100. Took a month.
panteradougpanteradougMember
quote:
Originally posted by Bosswrench:
Depends on who actually does the work. If you order the parts after pulling your ZF and do a tear-down to determine what wore out- the synchro assembly, the gear cone which requires full replacement of that gear and maybe the mating gear as well, or all of the above, and your assessment is correct & you reassemble it yourself correctly, is one price.

Or crate the 155-lb gearbox as befits a $6000 assembly and ship it to an overhaul facility, synchro R&R done this way can run several thousands of dollars and several months down-time.

Also realize that all new ZF parts including gaskets only come from RBT Transmissions and everyone pays full retail for them. Overhauls therefore all have the same parts costs so any variation comes from cheaper labor rates or cannibalized used parts recycled into your gearbox. Nothing wrong with that except used parts obviously won't last as long as new ones.... Some gasket dimensions are critical, too.

Last bill I saw (a dozen years ago) including shipping to RBT, tear-down, inspection and reassembly with a few new gaskets and only an inexpensive thrust washer replaced- no synchro required due to a mis-diagnosed noise- then return shipping, was for $1100. Took a month.


What I was alluding too is simply it is better to put the correct clutch in the car now rather then have to rebuild the ZF soon after putting in the wrong one.

It seems to me to be a simple equation.

This just seems to me to be one of those areas in the car where some go to "Bonzo the Chevy clutch guy because 'obviously' the original engineering was wrong because the Italians wouldn't stop with drinking Bolla and spilling it all over the blue prints?"

That simply isn't true. It is well engineered for 1970 limitations. It needed more development to improve it.

Conspiracy theories have their place, but not here with this car.


This pic of a Turbo shows how the mats should be cut to keep them away from the pedals. There is no possibility of the pedals bottoming out on the floor mat here.

If you did the pedal box modification of moving the mounting plate forward, then the pedals wind up closer to the floor at full travel than stock.

Check your mats.

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P peterfenlonMember
Well
I have received my new clutch spinner plate from The USA (McLeod)
so now have
both New McLeod pressure and spinner plates
new master and slave, quality stuff too from Roland Jaekel
New crank bearing
New release bearing
and not a gear can now be selected with the engine running.

over 3 months of buggering about with a sodding clutch system, unbelievable

adjustment of slave rod to longest possible to 0.5mm free play makes no difference.

bled with vacuum system no play in pedal.

if I stop the engine and select first gear as soon as I begin to release the pedal we are off and running.

I never thought a clutch system could be so problematical
goodrocgoodrocMember
Peter, last summer just on the way to join my fellow Pantera drivers in France I had Clutch issues. The Bolt that links the pedal to the master snapped and I had to repair it really fast, na never mind long story. My point is that I had really a lot of trouble bleeding the air out after the reapair and could not figure out why. Until it struck me the cars was pointing nose down in my driveway (maybe 10° slope) and after I put a Jack under the front and lifted it the air got out. I use a vacuum device to bleed btw.

A small air pocket was trapped in the master cylinder causing the trouble.
P peterfenlonMember
I think I have been making some of the problems with my clutch myself without the help of others.

Not knowing a great deal about the Marque, I tackled the clutch just as I would have with a TR2, E type or any other classic car that over the years I have been fortunate to own.

A clutch is simple, or so I thought and an effort reduction kit I also knew nothing about.

in short I have never put the adjustments recommended with the Effort reduction kit, and just tried to set the clutch up like any other bloke would.

I have spent a while today reading up on the ins and outs, found that I have measured the Master cyl rod in the wrong way to start with.

At least I have the quadrant around the right way, so I shall now set it up as per the settings in the books.

Master 2.91"
slave 3.07"
and hope for a decent space between flywheel and disc.

I must thank all those far more knowledgeable than myself for their efforts to help this numbskull, but hopefully we are on the way to getting it working properly.

Best wishes and a happy xmas to you all.

and the days are getting longer again too Pete
P peterfenlonMember
quote:
Originally posted by JFB #05177:
I GUESS your quadrant looks like this now.


the angle between links b & c would be the critical in the setting of the master cylinder rod. if b & C are near in a line, the pedal will lock up, you want the shallow angle about as shown. More angle and you start loosing MC stroke (and thus slave stroke)


No it doesn't, it was like this before you told me to turn it around, this is just so confusing see page 1 for your pic showing the incorrect fitment, and your comments.
jfb05177jfb05177Member
Please accept my sincerest apology in adding to the confusion.

My experience so far has only been “keyboard and monitor” and I assumed the photo I found and used to determine the motion of this linkage was correct. I was not aware of the Mike Drew article (posted earlier by David Nunn).

After studying the MDrew article, I went to the barn and looked at my linkage that has been rusting for 30+ years. As to which way is correct, I don’t KNOW. My modeling equations of the “possibly wrong” orientation did provide realistic results. Unfortunately the progression of dementia is such I doubt I will be able to model the “possible right” orientation and make a comparison so I would actually know for sure.

Again I apologize

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P peterfenlonMember
There is no need for apologies at all, I am very grateful for help. There isn't a definitive write up for Idiots like me.

Thank you for your latest picture, the slightly rusted one, My bracket is now that way around.

so with this latest info I will begin to put it all back together, fingers crossed, I have to be on the homeward run now!!! best Pete.

PS just noticed the split pins, what a grand idea.
P peterfenlonMember
quote:
Originally posted by Peter Fenlon:
There is no need for apologies at all, I am very grateful for help. There isn't a definitive write up for Idiots like me.

Thank you for your latest picture, the slightly rusted one, My bracket is now that way around.

so with this latest info I will begin to put it all back together, fingers crossed, I have to be on the homeward run now!!! best Pete.

PS just noticed the split pins, what a grand idea.


In reply to my own post.

NO luck, with the arm now in the right position
I cannot get more than 12/13mm movement of the slave cyl piston.
I am to try and go back to a direct no effort reduction system and see what transpires.


I have no leaks.
pedal pressure is continual with the new slave and master cyl.

I have an armoured flex line so no bulging.

I see there are different spinner and pressure plates depending on the ZF gearbox fitted,

sadly I didn't know and just asked the vendor for a clutch spinner and disc and the McLeod stuff came through.

I also noted that one poster said the height of the clutch pedal should be 1/2" higher than the brake pedal, I found this impossible to adjust when the effort reduction kit is fitted.
jfb05177jfb05177Member
I know this will be more difficult to measure, but your pedal travel should be stroking the master cylinder ~29mm to get the ~16mm at the slave.

your 13mm at the slave implies only ~23mm at the MC.

Is your MC the original ~19mm BORE? with the slave bore of ~25mm? vendors do sell a long stroke slave which has a smaller bore. (smaller bore gives MORE stroke from the same MC)

If the 12mm slave stroke is all you can get, then you might consider changing the length of the lever arm to the ToB?
P peterfenlonMember
quote:
Originally posted by goodroc:
Peter, please tell me which procedure you use to bleed the air out of the system?

Even a tiny air bubble trapped in the system will hinder travel of the slave.


I have tried using a vacuum system, using my compressor.

Also the good lady in the car pumping, and myself at the slave cyl nipple/zerk.with tube in half filled bottle.

2 questions for those who have working clutches.

1 how long is the travel on your slave please when pressing the pedal fully down, in mm if possible

2 is there a factory figure for the travel?
goodrocgoodrocMember
Peter I understand your frustration. Partly caused by your own "I just assumed" approach Smiler

There could be more than one reason for your troubles. Please tell me if/how you continued after fellow Pantera owners gave you their feedback? i.e.
1. Did you measure with a feeler gauge how much play between the clutch plate and flywheel when the clutch pedal is fully down?
2. Did you extend the fork bolt on the master to full? (its where the angle between b and c is a few degrees less than 180°) That will raise the pedal towards you (when not pressed) so it sits higher than the brake pedal and give maximum/full stroke on the master.
3. Did you remove the shift gate when troubleshooting to avoid misalignment being a factor.
4. Absolutely all air must be bled out.
5. Seems like you have managed to put the right parts together but also check the direction of the clutch plate. Only one side can be facing the flywheel! (should be marked)

I am sorry if this all sound so basic but I am just trying to brain storm...... I never had any of those problems. I bought a new McLeod Kit and removed the bell housing from the ZF to be able to carefully check/measure and adjust for required play between pressure plate (multi fingers) and throw out bearing. I rebuild the master and bought a new slave. All done on the same occasion.
P peterfenlonMember
1, there is no room for a feeler gauge between the plate and flywheel.
2 the geometry of the effort reduction system prevents this, I have yet to go none effort reduction by fitting the correct rod, which I assume (!!) will allow the pedal to be above the brake pedal.
3 alignment is not a problem, gate removal isn't needed
4 again all air is out, pedal is solid
5 plate is in correctly.

What is the travel of your slave piston?

I do appreciate assistance, I think all other posters are absolutely fed up with this problem that they have either solved or not met.

thank you for your continued help.

best Peter.
goodrocgoodrocMember
Peter you should not have to remove the effort reduction kit? What I mean by extending the rod is to install everything but NOT tighten the counter nut on the rod. Then with your fingers or a needle plier turn the rod to its maximum extension just prior to b and c being in a straight line (linkage becomes over-centered).

That should bring your pedal up and increase the possible travel/distance on the master.

I cant check my slave travel tonight but i will try to do it tomorrow and let you know.
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