Transmission noise....maybe..I think...

[KGBnut]

I have a noise that I think is in the transmission, but I'm not completely sure.

It started out as an occasional gentle thump in the drive train. I thought it was a loose bolt or something rattling around in the bell housing. I ran a very powerful magnet around on the flywheel a couple of times and found nothing. I pulled the inspection plate off the top and could find nothing.

After that, I drained the transmission and pulled the shift tower off and searched around in there and found nothing rattling around. It all looked pretty clean.

It is now doing it more often...thump...thump...clunk. You almost don't hear it, but I feel it in the pedals and in the shifter. Every once in a while, perhaps once a month, and only at low speeds, it makes a bigger CLUNK and it feels like someone tapped the brakes pretty hard for just a moment.

Has anyone ever experience something like this before? Any idea what it might be? Could this be an indication of a worn transmission? The transmission runs fine otherwise, and is not noisy. How do they behave when they are due for a rebuild?

Any suggestions would be helpful.

Ken

 

[crock]

May be the u-joint.

 

[Mitch//pa]

Do u get it coasting in neutral with the engine off

 

[Tom Endy]

possible that the two large nuts that secure the pinion gear have come loose creating thrust clearance in the bearings. The noise will telegraph up the drive shaft.

Tom Endy

 

[ursus]

Tom Endy may be onto the problem. Try jacking up a rear wheel with the transmission in neutral, parking brake off, and the grounded rear wheel blocked for safety. Rotate the raised wheel in both directions and listen for any soft clunking sounds.

 

[Tom Endy]

Tom Endy may be onto the problem. Try jacking up a rear wheel with the transmission in neutral, parking brake off, and the grounded rear wheel blocked for safety. Rotate the raised wheel in both directions and listen for any soft clunking sounds.

I was at a national meet years ago and a guy drove into the maintenance tent with the same complaint. The noise sounded like it was in the transmission. The consensus was that the transmission needed a complete overhaul. They pulled the rear and the transmission. After the transmission overhaul and $500 later when all was back together the noise was still there. They pulled the rear again and removed the torque tube and found one of the large nuts completely off and the other one about to come off. The fix was to put the nuts back on, try to set the pre-load on the pinion bearings, and make sure the two nuts are tight.

Tom Endy