Clunking Sound in the drivetrain

[dannyg2006]

I have a 1999 NBS Z-71 and have noticed a clunking sound when changing from park to reverse or drive. It seems to be getting worse. I pulled the driveshaft checked the u joints and added the grease for the output shaft and no luck. The sound seems to be coming from underneith the cab and not from the rear end. I did try it in 4-hi and the clunking quit. Put it back in 2wheel and the clunking came back. Any suggestions? All the fluids are good and the truck has 108,000 miles.

[tanked_darren]

Time delay from when you switch? Does it hammer? Is it a 4L60e? Might be on its way out. These transmissions eventually do this at my job site and the only prevention is stopping before shifting. Even then the 4L60e is kinda weak. Seen alot of new trucks do this after even 30k of hard shifts. Automatics hate it if you don't completely stop between reverse and forward.

[dannyg2006]

Time delay from when you switch? Does it hammer? Is it a 4L60e? Might be on its way out. These transmissions eventually do this at my job site and the only prevention is stopping before shifting. Even then the 4L60e is kinda weak. Seen alot of new trucks do this after even 30k of hard shifts. Automatics hate it if you don't completely stop between reverse and forward.

 

 

Maybe 20-30 seconds. As soon as I tested it in 4 wheel high, I put it back in 2 wheel without moving the vehicle and when I change it from park to drive or reverse the clunking returns. But in 4 wheel no clunking at all. And I'm pretty sure that it's a 4L60e with the truck being a 1500 with a 5.3L.

[Z45]

Probably just play in the rear drive train, wear and tear.

[KMGZ400]

my 2001 silv same as yours always clunked like that especially when putting it into reverse. has 115k. like elcamino said, its wear and tear.

[dannyg2006]

It's driving me crazy. Don't know if I should replace the slip yoke with the "gold plated" one or rebuild the rear end. GM mechanic told me that the rear end had normal play when we removed the drive shaft.

[kstruckcountry]

I wouldn't worry about it, but check your u joints. Wear and tear.