help, clutch chatter problem and cant fix (long)

[Boss300]

I have been fighting a clutch chatter problem on my 83 F100 300-6 3 speed manual for a few years now. It all started when i changed the original clutch out and had a bad chatter after that. I had the flywheel resurfaced when I changed it too. Since then I have changed the clutch twice and put a new flywheel in it. I even bought the more expensive Luk brand clutch the last time. I put a new bellhousing in with a good ball stud for the clutch fork and put in a new clutch fork. The mechanical clutch linkage was gone through and I put new bushings in all of it. The motor mounts and transmission mounts are also new. Then on top of all of that, I had the transmission rebuilt. I dont know what else there is to change or try to fix. To top it all off, the problem is very exagerated in reverse and sometimes the only way I can back up is to dump the clutch and spin the tires, otherwise it shakes the truck so hard the engine stalls because of the carburator flooding. It very rarely chatters when going forward and will only do it when I let the rpms get very low. In reverse, it will do it regardless of the engine rpm. Another thing it does is that when you downshift to 1st gear to slow the truck it will also chatter really bad and it has even done it while rolling forward when the engine is not running and I let the clutch out to stop the truck the last few feet that it rolls so it seems to be a torque issue when the engine torques to one side. Has anybody ever experienced this or does anyone have any ideas on what to try next? Convert to hydraulic clutch linkage or make more solid motor mounts?

[ctubutis]

Originally Posted by Boss300

It all started when i changed the original clutch out and had a bad chatter after that... it has even done it while rolling forward when the engine is not running and I let the clutch out to stop the truck...

You've replaced all those parts (sometimes multiple times) yet the problem
persists, even when the engine isn't running? Is this a 4WD by chance?

The first thing to come to my mind is U-joints, then would come alignment of the
other drivetrain components. It seems to me the problem isn't in the clutch, it just
manifests itself there....

EDIT:

The Ford factory shop manual lists for possible causes:

- Engine roughness
- Throttle linkage improperly adjusted
- Equalizer bar misalignment and/or excessive end play or wrong parts installed
- Engine misaligned. Not properly seated on mounts
- Body mounts improperly torqued
- Oil or grease on clutch disc
- Glazed flywheel surface
- Clutch disc warped or bent (little or no reserve)
- Pressure plate attaching bolts loose or missing
- Loose engine mount attaching bolts
- Loose transmission and/or clutch housing attaching bolts
- Clutch housing loose or misaligned
- Pressure plate fingers bent, out-of-plane or sticking (will not return hung-up)
- Improper clutch adjustment
- Release lever (fork) bent, broken or cracked