driveshaft question

[truckdude239]

when i put my transmission back in today i drove it down the road got an bad vibration when i put my new u joints in i didn't pay attention to the location of the drive shaft ( 2 piece drive shaft) will that mess my balance up on the drive shaft? or would it be something else. the virbation is coming from the back of the truck? thanks in advance

[truckdude239]

ttt

[truckdude239]

[sneakysnake]

Yes , you should always mark the ends and put them back the same way.
Do a visual check also make sure they are seated correctly.I had one that didnt go into the rear yolk, and let the cap shift.

[ChevLoRay]

Years ago, I replaced both u-joints in a '64 Bonneville. It had a baaaaaaad vibration afterward. Pulled the driveshaft out, thinking it might be bent....didn't have a reason for it to be so, but that was the voice of youth speaking in my head.

Took it to a NAPA store in Tucson, where the guy in the machine shop took it, shook it, then said no problem. He laid it on the bench, then took a shop hammer and gave a whack on each side of the yoke of the shaft.

When he shook the shaft again, each end flopped back and forth. Reinstalled it and drove many more miles.

Since that time, I have done the same thing every time I replace ujoints. If the ends don't flop, they're too tight, and you'll likely have a vibration when you drive it.

One other time, I encounted a vibration on a '66 Mustang. Someone had installed another engine/transmission and it had a bad vibration that they assumed was something serious...and traded it in at my buddys' car lot. A kid came and drove it, then asked me about the vibration. I got under the car, looked at the rear end, noticed that the u-joint was offset and setting on top of the tab that is supposed to keep the u-joint centered in the yoke of the rear axle. I loosened the u-bolts, centered the joint in the yoke, and tighted it back up. Another test drive and it was sold.