Clunk in driveline???

[Chaz]

What would cause a clunk noise in the drivetrain,,,,,??? Like after accelerating u let off the gas,,,,and theres a heavy clunk noise,,,,like a u joint but its not a u joint,,,my joints are not loose,,,,

If you quickly pump the throttle and let off it clunks back and forth,,,feels like tranny or rear diff,,,

89 suburban 4x4 v2500,,,,,

 

[Driver4r]

its the rear gears, when you let off, the tires actually drive the pinion. Then when you accelerate again it has to flip over to the drive side of the gear.
Its just play between the gear faces.
My 76 does it to, no big deal.

 

[87sierra]

The only thing i can think of is the rubber bushing or mount that holds the drive shaft up when it exits the trans and its worn out and lets the drive shaft move but it will usually then makes the clunk noise going in to gear never heard of it doing it when accelerating and letting off the accelerator

 

[crazy4offroad]

Check your motor mounts and trans mount. If those check out chock the wheels, take loose the rear driveshaft from the rear end and check to see if the play is in the trans by twisting the driveshaft back & forth. If it checks out grab the pinion yoke and twist it back & forth. If it has play your ring & pinion may have too much backlash, or your pinion could be loose. Either of these WILL destroy your rear end if not addressed. A little bit of play, like up to 0.024" is the upper limit. And don't try to take that measurement by twisting the pinion, you have to remove the cover. When you factor in gear backlash, looseness between the axleshafts, side gears and spiders, just twisting the pinion can seem like 1/2" or more of backlash and that's just not true.

 

[Zaar]

have to agree on the rear bet you have too much play better address it my k5 did that to me and i just ignored it thinking i would be ok then a parts trip on a cold day and a loud grenade went off boom there it was i blew the rear out lost a couple teeth on the gear. and it was clunking to the house what a pain .

 

[89Suburban]

Check your u-joint straps.

 

[Chaz]

Theres a shift kit in the tranny, th400, and it clangs going in to reverse hard everytime,,,but that clunk in the driveline worries me,,,my stepson had a blazer with a 10 bolt rear and that thing exploded on the freeway,,,shot metal out the rear cover,,looked like a large bullet hole coming out lol,,,,i guess ill go have the rearend checked out,,,thanks for the responses

Last time I had the rear end off the ground i remember there was a lot of play rotating the wheels forward and backward,,,,