The Stovebolt Site Forums The Shop Area Driveline Driveshaft vibration

I have a '41 AK that the clutch, driveshaft/torque tube and rear end were rebuilt last year. They had a real problem with the driveshaft and a bushing in the torque tube. Had to have the machine shop get involved. Something about a bushing getting pressed out and a new one made and installed.l

Everything worked fine for awhile and then I started getting a "ratcheting" noise from driveline when slowing down. The shops both said was just a "self clearing" issue . That has got much better. Now I have a vibration in driveshaft at 45 mph and above. Doesn't sound or feel like a U-joint. Only happens at speed and goes away when below 45.

The shop/mechanic who did the work is not longer available to ask. Any suggestions ? I have already thought about not going above 45, but I put the 355 gears in to be able to cruise at 55.

Get under the truck with the rear wheels raised and turn the driveshaft by hand and see if there is slop or slack in the U joint before the axle begins turning. Even a few thousandths of an inch of play can give you a vibration.

Try to move the shaft from side to side and see if the is any play at the U joint / yoke.

It has a torque tube. Can't turn driveshaft. you can feel it move when you turn wheels.

How much "free play" should there be when you move rear wheel before you feel drive shaft move?

Also, when I turn the wheels you can hear a soft ratcheting sound coming from driveshaft.

I don't know if I have no problem, small problem or a big issue.

I think you'll have to remove the u-joint cover and inspect that. If the shop didn't refill the u-joint bell it may have already worn out. It's a bushing type u-joint (no needle bearings like modern u-joints) and relies on the transmission lubricant in the rear half of the transmission for lubrication. It's also possible that the shop didn't get a seal behind the new torque tube/shaft bushing installed correctly and the lubricant has drained out into the rear axle. You could pull the rear differential fill plug to see if it's overfilled.
My money is on the u-joint being the problem.
I'm also suspecting that the "self clearing" comment by the shops was just a way to blow you off. Most noise issues don't fix themselves, especially ratcheting type noises. They usually get worse like yours has.

Thanks, I am going to look at u=joint. The truck has a GMC 228 engine and a 4 speed. is the transmission the same on the GMC and Chev engines?

ronsway Better listen to klhansen,that ratchetting noise was probably the no rollers u-joint being killed by no lubrication. Is now loose enough to give vibration. Once had a farm truck dry tranny that squalled terible,went to drain it no oil,filled it waited overnite just fine the next day.

The transmission for GMC and Chevy are the same.

As stated above, the u-joint ball needs about a pint of gear oil. It is often forgotten......

Question: If you drive over 45 to 55 does the noise go away or get louder???