Driveline clunk... P,R,D

[Wahugg]

Hello all.

Today I have notice a horrible clunk in the driveline has devolped. When at a stand still, with the foot on the brake, a good solid metalic clunk will occure when shifting from Reverse to Drive, or Drive to Reverse. Then there is also a good solid metalic ping when I shift it into park.

Could this be the U joints? I didn't notice excess play in them.

Or can this be a more serious tranny/ TC or differential problem? I did have a tranny leak on the return line from the intercooler, but that was fixed and the fluid changed (not flushed). Could that be causing this problem?

All fluids are current and good, just confirmed by myself checking them.

Any help would be appreciated

-Wallace

 

[The_Roadie]

Most likely to be u-joints. Less likely but possible is differential backlash. You said you checked even the diff fluid level? How did you check the u-joints? With the rear wheels in the air?

 

[xj2202009]

Most likely to be u-joints. Less likely but possible is differential backlash. You said you checked even the diff fluid level? How did you check the u-joints? With the rear wheels in the air?

I would check the motor mounts and transmission mounts

 

[HARDTRAILZ]

I felt no play in my u-joint until I pulled the driveshaft and could see it was F'ed. It popped going into and out of gear for awhile. It played hell on pinion bearing for not changing it right away since I kept searching for a cause after thinking the lack of play meant the ujoint was ok.

 

[Wahugg]

Well I haven't had the trailblazer for about a week now due to a mess up at the dealership.

But the clunk is still there, and when I checked the U joints, the wheels were on the ground, and the tranny was in park, and I tried to rotate the drive shaft with my hand. It would turn only a little, literally 1/100th of a full rotation. I might drop the drive shaft to check. Is all I have to do is undo the 4 bolts on the rear diff to drop the shaft?

Thanks
-Wahugg

 

[xj2202009]

that is normal play,

My sugestion is:

Have someone sit on the driver seat and while holding down the brake pedal, shift from park through the gears.(let engine settle into each gear before moving to the next, going straight from drive to reverse and vise versa are best gears for testing motor mounts) ,observe engine motion how much the engine moves and listen for any clunks( if motor mounts are good you should seen hardly any movement and definitely no clunks)