Reply to "Five modifications NOT to do to your Pantera"

Clutch, long throw slave:

We all agree that it’s critical that we get the clutch to fully disengage before shifting gears; if not we’ll soon wear out the synchros in our expensive ZFs. To make sure that we have both full disengagement and of course full engagement when the clutch pedal is not pressed down, the clutch master and slave and the clutch itself have to be right, and well-adjusted. However, some have bought long throw slaves, which of course make adjusting the clutch easier, but it comes at a price: It makes the clutch pedal harder to press down. And who wants that, who wants a harder clutch pedal, unless you’re trying to discourage your wife from driving the car?! Some then add clutch effort reduction kits(!), which more or less compensate for the long throw slave, so they are back to square one. You can’t cheat physics; the effort required and length of the arm always correlate, so you cannot invent a contraption that delivers a longer throw without increasing the pressure needed or vice-versa. If you can, you have invented a device akin to the perpetual motion machine, and will soon have enough money so you won’t be bothered fixing your Pantera yourself.

Again, did the factory build cars that were not able to properly engage/disengage the clutch? No they did not. The clutch just needs to be properly adjusted with no leaks or air pockets, and needs to be a Pantera-specific clutch rather than one designed for a Mustang or a pickup truck. Correcting the issue instead of compensating for it. Working As Designed.

So how do you adjust the clutch properly? That’s not so easy, because if you look in original Ford literature, there are several ways mentioned. When I replaced the clutch slave I tried reading these and put the advice together in one single instruction. Here it is below; if you use this, you don’t need a long-throw slave:

First, the basics have to be right: A good master, slave, pipe and line, and a proper Pantera clutch, not just a Mustang clutch. And the fluid has to be free of air.

1. Master: pedal should be adjusted so at rest it’s either at or 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 1/4” gap to the firewall/carpet.

2. Clutch pivot shaft arm: the arm from the ZF to the slave pushrod end. The clutch arm should be at a 90 degree angle to the pushrod/slave when the clutch pedal is pressed halfway down. Any other angle will result in the slave pushrod linear movement translating into less rotational movement of the clutch pivot shaft. Maybe you should move the arm a notch on the shaft? Also check that there’s free movement to ensure that when the clutch pedal is fully depressed, the arm or the retaining bolt/nut doesn’t rub on the ZF or bellhousing. If the arm isn’t adjusted properly and the retaining bolt/nut touches, it will limit clutch movement, and can even break the bellhousing. And get a properly sized clevis pin; my car’s previous owner had just used a bolt that was 0.3mm less in diameter, resulting in some slop in the system.

3. Slave adjustment bolt: Temporarily remove the spring. Use your hands or a tool to move the clutch pivot shaft arm rearwards, and feel for when the fingers of the clutch release fork touch the throwout bearing inside the bellhousing. It should be easy to feel. While holding the arm in that position, turn the adjustment bolt so that it almost touches the stop on the slave mounting 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 pushrod: Some suggest that the pushrod is used to position the resting position of the clutch pivot shaft 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 pushrod so that the slave piston is almost fully compressed with no bottoming out. With the system at rest, take out the clevis pin and by hand press the slave pushrod 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 pushrod, so that they do.

With all this done, you should have a clutch that neither slips nor grinds synchro teeth. And of course you must press the clutch pedal all the way down every time.