Torque Tube - Inspection

any symptoms? driveline vibration? grindy noises? extreme clunk caused by on/off the throttle during light cruise?

know the history of the car? how many miles on it?

the middle bearing tends to minimize vibration, if anything. its just a dumb old sealed bearing, so if it goes bad/gets dry, it ought to GROAN and RUMBLE, not vibrate.

interesting to contemplate what effect that center bearing has on U-joint wear. if it's even marginally intact, i imagine it would lessen the excursions a bad/worn U-joint would make.

the V8 TT driveshaft setup is different from the six. the six has a single joint up front, a slip joint in the rear. the V8 has a constant-velocity setup made of two crosses in a holder up front. yup, ther six has ONE joint, not the two required for constant angular velocity. i have no idea why this works, but it sure does, the TT classic six the smoothest car i ever drove.

these details are in the TSM, and Frank, FARNA here, knows more than i do about this stuff.

also Ujoints dont tend to fail suddenly like that, do they? have you checked the other peculiar TT-specific junk under there? there's the side sill thrust bushings, hiding up along side the rear x-member. there's the big trunnion rubber seal, that both seals out dirt etc and keeps the nose ot the TT centerered (if the rubber falls out, THAT might suddenly make noise). or rear trans mount failure, or two of these? how's the rubber under there? we know it's very old, ... lol.

cruising easy flat and level 45 mph in top gear, does it CLUNK on slight accelleration? CLUNK on slight decel? if you accel light, to take up the slack, does the sound change with added torque? etc

Check every other source of possible vibration first. The CV joint has a spring and pin assembly in the section between the two cross joints. The purpose is to keep the two cross joints aligned. If that fails the CV joint will "flop" and you'll get a bad vibration. There are no repair kits that I know of, but Blaser's was talking about having one reproduced a few years ago, you might want to contact them and see. Otherwise, it's get a driveshaft shop to lengthen the front of the shaft (front half is tubular, rear solid)and eliminate the CV joint. 56-62 V-8s only had a single joint. A lot was done to the 63s to make them smoother riding and quieter. Apparently some engineer thought the CV would help. Don't know if it did or not.

The 63-66 Classic has rubber mounts on the ends of the crossmember, between crossmember and body. Those fail before the CV joints. There is a short piece of channel around the rubber mount so that if it does fail the CM won't fall out. If it looks like the CM is sitting on that channel the mount has failed and the CM is moving as you drive. That will cause a vibration, much like a bad transmission mount in a newer car. Galvin's and other vendors have repro mounts for the CM.

My best guess is the CM mounts have failed, not the CV joint. The spring in the CV is over 50 years old now, but those rubber mounts aren't sealed and well, they are rubber...