new clutch, pedal much too hard - looking for a softer setup

Not knowing specifically the combination of factors involved in your install, just generally speaking, the "Long" style will have the greatest effort in the pedal.

The clutch at the other end of the effort spectrum is going to be "diaphram" style like the Centerforce.

The Centerforce specific to the Pantera is going to be a 10.5" od disc. Most aftermarket clutches are going to recommend an 11" for the Cleveland.

I was initially concerned with the holding ability of the Centerforce as a result but am agreeable that it is acceptable with no issues.

I don't see how the disc diameter would result in lower pedal effort but in this case it may? That makes no sense scientifically but there seems to be something to that.

If you are running a "stroker" engine with more cubic inches then a 351 (5.7L), it probably would be wise to use the larger disc but frankly all Panteras seem to be applicable  to some kind of a various "witches brews"?

If you choose to go with the Centerforce dual-friction, be aware that the thing is "spooky" first installed and takes a bit of driving before it stops sporadically slipping mostly from at rest.

Centerforce does warn about that but the amount of slippage and the length of the break in period does seems to vary from car to car.

Just my observations, "your mileage may vary".

Oh...one thing to add that may be significant...in the Pantera the seating position can effect the effort needed to operate the clutch pedal because of the leverage change cause by the seating position. Just something to consider?

Some vehicles do better then others with clutch type changes. For instance in a vintage Mustang, changing from the original "Long" style to a "Diaphram" style effects the entire design of the mechanical parts to the clutch pedal. The Mustang doesn't like the change.

The pedal stays noticeably lower then originally and needs help returning to where you want it. In the Pantera, that doesn't seem to mater because of the hydraulic system?

Additionally, the use of the "Long" in the Pantera originally seems to be a compromise and makes mixing ANY changes into the rest of the components problematic. The Pantera actually likes the diaphram type better. One reason being that a diaphram doesn't need as much travel to release as a Long does. Therefore, it's a better match to the Pantera then the Long.

I don't think that the various phases of the Moon have anything to do with it though...just in case you were going to ask but there may be more data on that of which I am not aware? You never know?

I have been thru a few set-ups. Started with a Centerforce & steel wheel when purchased. Owner complained about effort. Heavily glazed and shuddered like mad.

Replaced with the Centrifugal Centerforce. Clutch always dragged. Thought I had gearbox issue. Changed slave cylinders couple times, constant bleeding to get every ounce of movement. Hardest pedal I've ever experienced.

Changed to longer throw slave, bigger bore master, installed aluminum flywheel and 3 finger Hayes racing set. Worked great for some years. Still a bit stiff on the pedal. Not fun in Detroit traffic.

Now going with aluminum wheel, plate, and small diameter multi disc clutch. Installed a hydraulic throwout bearing all from McLeod. Whole set is alot lighter and not gonna last in traffic. Gotta do the bump, roll, ENGAGE!

I have a new 164T Centerforce aluminum fly and Centrifugal plate/clutch and the McLeod hydraulic conversion throwout for the Pantera on ebay right now.

If you have the clutch effort reduction kit, make sure the triangular bellcrank piece is oriented correctly. It is not reversible and if installed the wrong way, it will *#%¥-up your clutch release.

In my experience, the formula for the lightest clutch pedal possible is: a diaphragm pressure plate, a (flame suit on) McLeod hydraulic throwout bearing and a 5/8” clutch master cylinder. Unfortunately, installing a hydraulic T/O bearing is not a trivial undertaking. Set-up is critical but once set-up, they work great and are reliable. I’ve only used McLeod’s unit. Early on, they could be problematic, although I had no issues with them. Others did! It seems they were updating the design every 6 months, for a decade, but they now seem to have finalized the design. Bosswrench has had a Tilton unit installed for a long time, without any problems. McLeod makes an 11” diaphragm pressure plate for the Pantera, however; you need to call them to get the part #. Dennis and Adam Quella stock them too. I’ve used a McLeod 10-1/2” diaphragm pressure plate and had no issues with it but the Centerforce 10-1/2” Pantera pressure plate won’t work with a hydraulic T/O bearing unless you remove the counterweights.

I noted you have the “adjustable” throwout bearing, mine is adjusted by adding/subtracting metal collars from the stack to set where the bearing sits relative to the clutch fork…

Maybe you can adjust the “throw” by adding or removing a collar?

This probably wouldn’t change the effort, but might affect the engagement…

Rocky

The effort is relative. It depends on what you expect to feel.

Stock isn't a heavy feel at all. A diaphragm is a little lighter.

There is not a huge difference with the effort reduction kit installed.

No manual shift performance car that I can think of is pleasurable to drive in bumper to bumper traffic. They make automatics for that.

An aluminum flywheel will just accentuate the issue.

I had a very heavy clutch on a Pantera after installing a McLeod 3 finger clutch setup.  The car was a 72 pre-L.  Then I added the clutch effort reduction kit from Wilkinson and the clutch was immediately friendly.

@rocky posted:

I noted you have the “adjustable” throwout bearing, mine is adjusted by adding/subtracting metal collars from the stack to set where the bearing sits relative to the clutch fork…

Maybe you can adjust the “throw” bu adding or removing a collar?

This probably wouldn’t change the effort, but might affect the engagement…

Rocky

Thanks for all the valuable information here! Regarding the adjustable throwout bearing: yes, I measured before assembly and adjusted the bearing (to maximum thickness). That way it works, but the travel is basically to short for this clutch setup for disengaging completely when having a minimum free travel at the throwout bearing.

Eugen

@panteradoug posted:

The effort is relative. It depends on what you expect to feel.

Stock isn't a heavy feel at all. A diaphragm is a little lighter.

There is not a huge difference with the effort reduction kit installed.

No manual shift performance car that I can think of is pleasurable to drive in bumper to bumper traffic. They make automatics for that.

An aluminum flywheel will just accentuate the issue.

Thanks, yes, I know, I have and had a bunch of racecars and classic cars with heavy clutches, but the Pantera in this new setup is really something different.

In my Pantera, all of the issue is in getting the relationship between the throwout bearing, the clutch fingers and the slave cylinder to where the release is correct.

In the Pantera it isn't easy to measure the clearance between the disc, the pressure plate and the flywheel but when I set up clutches, that is a key number. You need to do that with a feeler gauge.

The diaphram requires less clearance at full travel then the Long type does.

You are going to ask me what those numbers are. At this moment, I don't honestly remember. I'd need time to come up with those, but those are the key numbers.

I do remember that with the original Long type that I took out of there, the slave was maxed out. The diaphram provided more clearance.

Why the Centerforce is spinning like a dumb-dum for you is inconsistant to what I have with them.

I have a Centerforce in my '68 GT350 and my '73 Pantera. Neither has any kind of issue but as Shirlock Holmes once stated, "once you eliminate all of the obvious, whatever remains must in fact be the answer". No kidding right?

What did you do with the pilot "bearing"? As per the pilot bearing discussion, there is a maximum tolerance allowable on the wear. If you want to be comprehensively scientific you need to look at that also.

Using Marlin's numbers on that would be highly advisable,

Thanks for all the helpfull insights! In private messages I heard good things about the RST Dual Disk Organic Clutch from Pantera Performance. That way I could keep my new expensive aluminium flywheel and the new throw out bearing, when I am correctly informed.

thanks............Eugen

I haven't used an aluminum flywheel in these cars.

Is the total thickness at the cltch disc surface the same as a steel/iron one? It d oes NOT need much difference to complicate the matter with a full new disc.

It is worthwhile to consider measuring the thickness of the flywheels and compare them. Aluminum v steel/iron.

There may also be a variation of the thickness of the mounting flange to the crankshaft or even the tolerance that the stock crankshaft flange is machined to? I haven't looked for that since you would need really more then two engines in one place to compare that. That would effect the dimension available for travel of the throwout bearing.

I do remember Gratiot Auto Parts in Detroit selling their "Pro-Stock" line of rebuilt clutches.

They would resurface the pressure plate also like you would do with brake rotors. That would contribute to more clearance for travel and it is so tight in a Pantera that even a few thousands help although we are probably trying to gain hundreds in travel?

If you examine a clutch disc, you will notice that they are not flat.

They are made with the radial fingers twisted.

That is called Marcel. It is intended to act as a spring and to help the disc release from the flywheel.

That twisting from flat contributes to the total clearance needed.

I don't know if the amount of Marcel  is a constant with clutch manufacturing or not but it may be that varies as well?

Some racing clutches have no Marcel. That makes them lousy street clutches. No Marcel makes them chatter and they tend to feel like that they are only 100% on or 100% off. Forget about driving those in "traffic".

You should inquire about that feature,i.e., whether it is included or not in the clutch you are considering. When you go to a multi-disc design, it is essentially a racing clutch. Exercise caution there.

This may be getting "into the weeds" but sometimes that's where the answer is.

I thought I read that in the DeTomaso factory, the Marcels were removed from the disks, and the clutch disks were re-riveted together, due to the need for more space between the pressure plate and the flywheel?

I recall this from a while back, and it should only apply to the original (factory) clutch assemblies - if true.

This wouldn't affect the pedal effort, though...

Rocky

If you search on the word "marcel", you will find a couple threads referencing the Marcel being removed, or flattened, one by Dan Jones, and one by a dude named Pantera Doug.

Wow. Talk about dynosaurs? I certainly qualify but I don't eat raw meat anymore. You know? The doc's and all that jazz?

I remember the discussion vaguely BUT I find zero Marcel difficult to believe that would work as a "streetable" solution?

It isn't like the Pantera was the first to use the ZF. The issue is that there just isn't enough room for the throwout bearing in the bell house. I do think that someone goofed there.

My "clutch expert" retired. Sits and watches reruns of Jeopardy all day. If you think I get pissy, you ain't seen nutin' when you talk to this guy? Actually I am a reflection of my NY socialization. The race teams here when I was a teeny bopper were just plain nasty. I kept some of the wrenches they threw at me. Good stuff! Screw them. Catch me if you can to get 'em back!

If I could, I would ask him if the amount of Marcel varies or is it a standard dimension. They were always playing with the clutch in their Pro Stock Camaro.

If you research Marcel, I don't think there will be any mention of the amount built into the disc? That may be somewhat of a trade secret so to speak?

Maybe someone here can find something on that. There is nothing wrong with a forum being highly educated.

It’s my understanding, the factory disassembled the discs, flattened the marcel, then put them back together, in order to reduce the thickness of the discs.

@davidnunn posted:

It’s my understanding, the factory disassembled the discs, flattened the marcel, then put them back together, in order to reduce the thickness of the discs.

Ford must have been thrilled with that?

What did they do with the Mangusta?

My 2 cents- Not from personal experience, but the Mangusta with a smaller, less torquey engine, different linkage under the dash and a different set of parts from pedal to (different) flywheel, just don't seem to have clutch problems.

Next, with modern throwout bearings, free play is often no longer necessary, but one should not go past zero-clearance to an actual clutch preload. Mexican-made throwout bearings sometimes disassemble themselves during drives so they obviously are not well made. Finally, I've found that some Panteras no longer have the 1/8" thick steel motor-plate between the block and bell housing, which narrows the available clutch distance even more. It needs to be there. Ford was not involved at all- DeTomaso designed & built which may be significant.

One thing some guys miss: the Pantera effort reduction system was never offered as a new assembly so all added ones are take-outs. And they are built with a dozen unhardened steel to steel pivots which have NEVER been lubed, even at the factory. So after 50 yrs there's always wear which significantly cuts possible clutch throw distance. Some owners have gone through the system and added bearings or bushings for all the pivots but its an exacting, tedious machining job.

I forgot about the backing plate. That would have come in the engine assembly from Ford. The one in my car is .080" thick.

Don't misunderstand. I'm not arguing, Ford's issue was that they were the ones Warranting the car. Not Detomaso.

The Detomaso logos on the valve covers were there because Ford literally would not let Detomaso take the valve covers off from the engine assembly they delivered for the Pantera installations.

While I have heard this story about removing the Marcel. I have also been mislead by inaccurate Automotive Journalism at times. So I have doubts about the accuracy of the claim? I need to consider the original source of the information.

If Ford wouldn't even let Detomaso change the valve covers, how would they let them modify the clutch disc from what Ford delivered to them? Ford's review on the ZF was that it was pittifly fragile.

While I do question journalistic accuracy at times, it was reported that Ford REQUIRED selling dealers to stock 3 ZF's as they expected a high failure rate.

While I find this an interesting subject, I'm wondering if it is just what we now refer to as a Conspiricy Theory? I don't buy it.

The fix was going to a long throw clutch slave. It gives you more adjustment available for clearance.

I'm thinking that the number for clearance is .035" for a diaphram and .045" for a long? You also need to "mic" the thickness of the clutch disc, as some are thicker new then others.

I think the number on that is .375"?

It is true that you can now get "constant" contact throwout bearings but the culprit there is going to be the finger on the pressure plate.

I personally have had issues with Centerforce pressure plates in that the diaphram fingers were not sufficiently hardened and the throwout bearing cut through them. It was as if the fingers were just painted black. Not flame hardened.

I prefer non-constant contact types but I can't always get what I want.

My '92 Taurus SHO was a constant contact design. When I did the clutch I went top shelf with the Centerforce Dual Friction. It failed at 12,000 miles. Bummer. It is a constant contact design from Ford and the Centerforce was a direct replacement.

That is where I met my new acquaintance Gene, the Centerforce factory rep. Let's just say that we had a very heated argument and both of us wanted to insert this clutch into the others private orifice where the sun don't shine?

Front drive cars are SOB's to do a clutch in. EVEN IF you wanted to pull out the entire engine/transmission drive train, you have to drop the entire thing out from the bottom and lift the car high enough to slide it out. Not something that I look forward to do in my free time.

A Pantera clutch by comparison is child's play but it's just a little bit different.

I don't remember specifically but I think the engine assembly delivered to Detomaso had the Ford bellhouse, clutch assembly,  throwout bearing and fork included? There are a couple of Detomaso factory pictures of workers unpacking the engines and the bells I think were still on them?

ACT is advertising their clutch discs as "reduced Marcel".

https://www.advancedclutch.com...t-sprung-clutch-disc

I don't see a number stated though.

UPDATE: finally I found the perfekt solution! This clutch (CENTERFORCE DF021057S Dual Friction Disc/Pressure Plate Set) I bought from a member here on Ebay works perfectly. It fits the aluminium flywheel (MCL 563200 1964-9 5 SBF) with 8mm bolts. I had to fabricate 3 centering pins but otherwise just a bolt on.

The throw out bearing (MCL16525) also works. The setup does not need a long throw master cylinder. With the short throw there is enough travel for the clutch to disengage.
The pedal effort is almost nothing - as if there is no clutch at all. And the best thing: the clutch shudder is gone, total smooth engagement! So much more fun to drive!

Eugen