Slave Adjustment

Did you look here http://www.panteraplace.com/page124.htm on Pantera Place?

Mike

Some cars had the small (6mm) screw with the head facing aft & some had it facing forward. Turn the adjusting screw in the direction that will make the return spring longer. This will move the top of the clutch arm towards the rear of the car.

You could also have a problem with the hydraulics. The master cylinder could be by-passing &/or there could be air in the system.

Was everything working correctly before the problem started? Or was there work done recently?

Thanks for the webpage, I hadn't checked there in a while. It may have recently occurred because it seems the screw may have backed out some. I just screwed it in some more to make the bracket come more toward the rear of the car and it was a little better. It seems it works perfect when the car gets warmed up, go figure. I plan to bleed the system soon anyway with new fluid, so that will take care of any air if in there too. Thanks guys!

If the clutch is engaging with the pedal just off the floor I hope you find that you have way too much free play, thus not disengaging the clutch fully. If the free play looks good then you might have a master that is leaking past the piston (sometimes more when cold), a linkage problem or something messed up with the pressure or clutch plate. If the master and slave are in good shape and the clutch assembly is correct Pantera part I find the Pantera clutch system works great with stock parts.

Mike

Yes Mike, I am trying to convince myself it is not the master (pain in the butt to change with a bad back).

In your website description with the wrench as a feeler on the arm, is the car running when you rock the wrench to get a feel for the free play? It is pretty tight and hard to feel when not running, but if running, then maybe you could feel it better on the wrench when the throwout bearing begins to contact the clutch fingers? I even had the wife take a look see in the engine bay when I began to press the pedal to see at what point any movement takes place at all on the slave.

Yes, some folks feel the free play with the engine running because it may be easier to detect when the throw out contacts the clutch fingers.

Mike

Been raining here in CA so I didn't get a chance to mess with it yet. However, just pumping the pedal it is feeling a little soft in my opinion, and when this happend on my orange car, it was the master. I also looked at photos of the slave adjustment from several months ago compared to now, and now I see that I have the slave arm adjusted more to the rear of the car, but it still has some issues with the car engaging at the moment I release the clutch off the floor. Is there some method to determine if problems are at the master or at the slave? I know some recommend to change both.

Don't forget as the clutch wears it becomes thinner and this will move your engagement fingers toward the throwout bearing, reducing or eliminating your clearance between the fingers and throwout bearing. this will eventually waste the throw out bearing, if you moved the arm towards the back of the car you are eliminating the freeplay or clearance, bad things will happen,You may be out of adjustment or your clutch is needing replacement.

Mark

Thanks for all the input. One thing good about having more than one Pantera is that you can compare things. My wife took photos of the slave before and after with me pressing the pedal on all my cars, and the black car was minimal distance movement at the slave compared to the others. Pedal is just weak feeling too, so now to decide whether to start with the master or the slave replacement. I wonder who has this Master in the attached photo?

Just picked up my polished long throw slave from Byars and will try that first to see if it helps. The aluminum one I had was leaking. Hot damn Byars sure did polish it up good! He even chromed the snaprings, nuts, etc. Maybe I will just use it as a paper weight for a while and just look at it.

It seems the slave extension porton of this new slave is about 1/2 inch longer than my other slave when it is pushed all the way into the slave. As shown in the photo, the eye screw is screwed in as far as it will go into the slave even if I back out the nut all the way. So in order to fit the slave into it's bracket on the car and have the eye connect to the arm on the transmission, it seems I need take the arm off the transmission and readjust it a little more toward the rear of the car to give more space. Other option could be to grind down some of the eye screw to make it shorter so that it will screw into the slave further, but that doesn't seem like the way to go. Anyone ever had to adjust their trans arm? I suppose this is ok, makes sense to me anyway.

It appears to be a CNC aluminum master cyl. used in sprint cars etc and sold (Hall?) in the LA area for Panteras. One of the few that are a bolt-on since clutch master bolt spacing on Panteras is tighter than normal so cheaper Girlings etc won't fit directly.
I notice your brake booster on this car has the reverse vacuum line setup. Most Panteras have the vacuum line going up thru the same hole in the floor as the clutch master line. Has the booster ever been replaced? Just curious- the placement of the line is only important if you carry wide stuff in the frt. trunk. I needed such a booster when trying to fit a high-pressure 4" x 16" spare tire/wheel in a front trunk. Boosters are symmetrical & when rebuilt, can be assembled with the line in any of several positions.

quote:

Originally posted by Bosswrench:
It appears to be a CNC aluminum master cyl. used in sprint cars etc and sold (Hall?) in the LA area for Panteras. One of the few that are a bolt-on since clutch master bolt spacing on Panteras is tighter than normal so cheaper Girlings etc won't fit directly.
I notice your brake booster on this car has the reverse vacuum line setup. Most Panteras have the vacuum line going up thru the same hole in the floor as the clutch master line. Has the booster ever been replaced? Just curious- the placement of the line is only important if you carry wide stuff in the frt. trunk. I needed such a booster when trying to fit a high-pressure 4" x 16" spare tire/wheel in a front trunk. Boosters are symmetrical & when rebuilt, can be assembled with the line in any of several positions.

Yes Bossman, the master (whole car) was from Hall. I looked at early restoration/build photos, and I see two holes are present in the front trunk floor while the car was being built, but I don't know if it was added or the car was like that from start.

Now on to the slave: I picked up my long throw slave, and the small rod inside is longer than my current unit by about 1/2 inch. So in order for it to fit into the car, I would have to adjust the clutch arm way back to the rear of the car, and going that far just seems odd, and leaving huge room for the small arm adjusting screw (at least 1 & 1/2 inch). The photo shows the size of the rod on my old unit next to the new unit with both screws screwed in all the way. I could cut the bolt on the new unit to allow it to go in farther, but that still wouldn't create enough room (maybe would if I totally eliminated the nut on the rod as well). I think I may just chrome my old rod and bolt and then use this in the new unit. But this made me think,is the rod length the only difference in a long throw slave from a regular unit? That wouldn't make sense because just a longer rod wouldn't create any "longer" throw from starting point to extention. My old slave unit main housing is almost identical to the new long throw, so maybe I had an aliminum long throw in there to begin with, and only difference is this longer rod.

May I suggest the obvious?

Go back to Don/Bobby at Byars and ask them for the answer?

Replacement parts should not involve re-design, IMHO.

Larry

Jan,

I have that CNC clutch master on my GT5. I had problems with clutch disengagement and spent some time looking at the hydraulic system. I don't recall the exact dimensions, but the CNC MC is a fairly small bore, in fact undersized for the std slave. Look at the MC and slave bore diameters and MC travel to guage how much slave travel you'll get. If the slave is a larger bore than the MC you have less than 1:1 ratio, which is what I had happening. A long throw slave should be a smaller bore thus a fixed unit volume from the master will move it farther.

This doesn't address the rod length aspect, but I'm thinking you may find that Byers sells a corresponding slave bracket that is set back farther to match the slave, each vendors aftermarket products vary somewhat and are not always interchangeable.

Good luck,
Julian

Yes guys I did plan on checking back with Don, but I like to post things here too, as I learn from all this stuff myself. Byars are always great, took it over today at noon and Bob ground the rod down and polished it up on the spot, now ready to put in. Now the wife can't complain anymore that my rod is too long.

Julian, I did compare my other slave to the long throw and you are right, the inside of the long throw is much smaller in diameter (maybe I will post a photo later side by side for rookies like me).

quote:

Originally posted by Joules5:
Jan,

I have that CNC clutch master on my GT5. I had problems with clutch disengagement and spent some time looking at the hydraulic system. I don't recall the exact dimensions, but the CNC MC is a fairly small bore, in fact undersized for the std slave. Look at the MC and slave bore diameters and MC travel to guage how much slave travel you'll get. If the slave is a larger bore than the MC you have less than 1:1 ratio, which is what I had happening. A long throw slave should be a smaller bore thus a fixed unit volume from the master will move it farther.

This doesn't address the rod length aspect, but I'm thinking you may find that Byers sells a corresponding slave bracket that is set back farther to match the slave, each vendors aftermarket products vary somewhat and are not always interchangeable.

Good luck,
Julian

Can someone explain the theory of clutch hydraulics? If I understand correctly, the larger or smaller the bore on either side makes a difference in throw length or ease of pedal pressure? Can anyone provide a table of what affects what and how?

I would think it would be a question of ease of pedal pressure. For the same pressure a larger bore (larger cross sectional area of the piston) would generate a greater force. Therefore, for the same amount of force required to disengage the clutch, less pressure would be required.

quote:

Can someone explain the theory of clutch hydraulics? If I understand correctly, the larger or smaller the bore on either side makes a difference in throw length or ease of pedal pressure? Can anyone provide a table of what affects what and how?

Dennis,

No tables, but some simple cylinder volume math which because you are dealing with two cylinders in a closed system, simplifies down to...

Bore Dia MC/Bore Dia Slave x stroke MC = stroke (movement) Slave

Agreed with Husker the ratios do affect pedal pressure, but this is usually secondary for most Pantera owners as std clutch disengagement is only around 50 thou. The post '72(?) cars had the pedal effort reduction kits too.

Julian