I have a 66 F100 which I changed from a tired-old 300 to a healthy 390. I used the original 66 granny-gear transmission, and the flywheel, bellhousing, and clutch assembly from the 73 F250 from which the 390 came.
When I put the 390 flywheel on the engine, I could feel something sticky on it; so I washed it off with solvent, dried it and installed the used clutch assembly, as it appeared to be almost new. When I drove the pickup, the clutch was chattery when releasing the clutch. It got worse as time went on, until I just couldn't take it anymore, so finally, I ordered a new clutch and pressure plate from Checker.
When I removed the trans to install the new clutch, the flywheel felt sticky again, so I polished it with a wire brush, washed it with laquer thinner several times, then installed the new clutch.
At first, the clutch was acceptable, but as time goes by, it keeps getting worse and worse. The last time we drove it, it felt like it was going to shake the truck to pieces each time I let the clutch out!
I thought the sticky substance was gasket sealer, which would burn-off with time; but this just gets worse with time.
Before I dump the trans out this time, I want to know I'm going to solve the problem. Should I install a different flywheel, have the old one surfaced, or what? Also , I want to make sure the clutch disc is in the right direction; the side with the springs sticking-out goes toward the trans, right.
One of my buddies says this is all caused by a leaky rear-main seal which is getting oil on the flywheel and making the clutch chatter.
i'd really like some opinions on this before I start, that tranny is a heavy old booger, and I don't want to R+R it anymore!

 

there are freeze plugs just behind the flywheel. Could the sticky stuff be anti-freeze leaking from them?

 

MAN!! There's one I hadn't considered! If that's the case; I might as well pull the engine, instead of the tranny. I'll have to check this one out. Thanks, Brett

 

Hey! I pulled the inspection cover today after work; (of course, I had to remove the right header, and broke the gasket into about ten pieces!) It is as clean and dry in there as the day I put the new clutch in!
However, CARRAS got me to thinking---If that was antifreeze on the flywheel, from a previous problem, nothing I cleaned it with would have removed the antifreeze. The only thing I know of that will cut antifreeze is water. I used solvent and laquer thinner---these would only have made it goopier.
Would it be worth a shot to have someone release the clutch while I rinse it out with water? I really don't want to pull the tranny if I don't have to!
Thanks a lot! You guys are great!!