I have a 2002 Tahoe with about 86,000 miles. I hear a loud click or "clunk" when I'm travelling down the road and either just start to step on the gas or I'm slowing down and the the vehicles downshifting. It's always a single "clunk" and I can feel it on the floor board. I recenlty had the front differential overhauled. I've eliminated the CV joint as the problem. I have noticed quite a bit of play on the driveshaft where it enters into the transfer case and the front differential. The universal joints don't look to bad. The joint at the transfer case looks like it could be getting a little worn. When I turn the drive shaft, I can hear the same type of "clunk" from the gears. Would this type of noise be caused by normal wear in the front differential? It sounds and feels like its coming from the left front wheel area. Is this something to be worried about? Could it be a bad ball joint?

 

There shouldn't be any "play" in the U-joints. Play will make itself known by clunking noise when changing direction. Worn gears can do this but shouldn't be that much wear at that mileage. I'm betting on U-joints.

 

Some vehicles may exhibit a clunk noise that can be heard on a 2-3 upshift or a 3-2 downshift. During a 2-3 upshift, the 2-4 band is released and the 3-4 clutch is applied. The timing of this shift can cause a momentary torque reversal of the output shaft that results in a clunk noise. This same torque reversal can also occur on a 3-2 downshift when the 3-4 clutch is released and the 2-4 band applied. This condition may be worse on a 4-wheel drive vehicle due to the additional tolerances in the transfer case. This is a normal condition. No repairs should be attempted.

 

Thankyou for the info 73shark, I'm planning on changing the U-joints in the near future just to be on the safe side.

ZX1100F1, I've noticed the noise occurring in between shifts and down shifts but it happens more often when the vehicle is coasting and I just start to press the accelerator. The noise happens before I can feel the vehicle respond. Would the torque reversal you described occur when I touch the gas pedal?