Mysterious Clutch Problem

I have spent the last two years trying to solve a strange clutch problem in my 1964 1/2 Mustang convertible. The car has a basically stock 289 with a 4 speed transmission. The clutch works beautifully for about the first 20 minutes on the road. Once I’ve been driving for a while and the car is up to temperature, the operation of the clutch becomes very rough. It feels almost like the throwout bearing is grabbing against the input shaft and not sliding smoothly.

I have had the clutch set replaced several times, and changed brands. I have rebuilt the z-bar assembly with all new parts, including the z bar itself. I have even rebuilt the pedal assembly with a new aftermarket needle bearing setup.

The clutch works fine, no slipping, no chatter. It’s just that the pedal operation gets rougher the longer I drive, but then returns to a normal smooth operation after the car has sat and cooled off.


Cool. Really cool. Did you know that the '64-1/2 was built on a Falcon chassis? It wasn’t until '65 that it got a chassis of its own.

I’d look for something that might be affected by the heat of the exhaust.

regarding the Falcon connection, whenever I go to the autoparts store, I always refer to it as a 64 Falcon 289. That will almost always get me the right part. If I say it’s a 65 Mustang, or even a 64 Mustang, I almost always get the wrong part.

As for the exhaust, I have the tri-Y headers on it. I’ve considered wrapping the headers for multiple reasons. The main reason is that I had them ceramic coated a few years ago, but the finish is coming off and they look terrible. But I just can’t imagine exhaust heat affecting the clutch operation like that.

Carry a gallon of water with you and the next time this happens, pour it on the “Z-bar” or cross link to cool those parts off and if that cures it, lose the headers. The stock 289 HYPO manifolds work just as well and solve a lot of problems that come with tubing headers…Have you removed that ridiculous helper spring that’s connected to the pedal cross shaft? They cause a lot of Mustang clutch problems…

Man that is a great suggestion about the water. If nothing else, it’s a great way to rule the z bar out. Thanks.

When I rebuilt the pedal assembly, I replaced the helper spring with a new spring and plastic bushings. I even bought a new bracket because the spring had dug a groove in the original. The pedal assembly is silky smooth.

I like the hipo manifolds a whole lot. I might eventually switch to them. Meanwhile, I might get my headers wrapped and see what that does for me.

I’ll try the water thing next time I drive it, and let you know what happens. Thanks again.