Double clunking

[Kens1990K2500]

My truck has about 180,000 miles, and the drivetrain has a lot of lash or slop. I've heard of slip yoke clunk, but every time I take off from a full stop, I get not one clunk, but two clunks. It's kind of embarrassing. If I very gently ease into the throttle, I can take off quietly, but it's a pain to have to feather the throttle all the time just to take off quietly.

What things should I be looking at to try to resolve the problem? Truck is a K2500, automatic trans, with 6 lug wheels. Not sure what rear axle I have.

 

[JOHNGAAA1]

U JOINTS?

 

[Scooterwrench]

U JOINTS?

Good place to start. While your under there you can check the pinion lash.

 

[Hipster]

A rotted u-bolt will let the rear slide on the springs and clunk. The lower plates collect crud and moisture. Can be an on/off the gas double clunk.

 

[GoToGuy]

Stop driving and inspect the joints, block the wheels, e brake on, get under and twist drive shaft feel and look at joints, movement, torn seals , excess play causes a " load / unload " clunking. Ring and pinion wear will clink also with deceleration / acceleration as power loads then unloads drivetrain. The slip yoke condition could be , not likely.
YEAR, make, model, eng, trans. Those are always needed to give the best answer.

 

[Kens1990K2500]

Stop driving and inspect the joints, block the wheels, e brake on, get under and twist drive shaft feel and look at joints, movement, torn seals , excess play causes a " load / unload " clunking. Ring and pinion wear will clink also with deceleration / acceleration as power loads then unloads drivetrain. The slip yoke condition could be , not likely.
YEAR, make, model, eng, trans. Those are always needed to give the best answer.

1990 Chevy K2500, 5.0L V8, 4L60 automatic trans.

Would U joints best be checked with driveshaft out of the truck?

 

[GoToGuy]

Grab the shaft, turn back and fourth while observing joints, excess play , or rust , or needle bearings , gone will be easy to spot.

 

[Caman96]

Not sure what rear axle I have.

Good guess… 9 1/2 14 bolt.

 

[Kens1990K2500]

Grab the shaft, turn back and fourth while observing joints, excess play , or rust , or needle bearings , gone will be easy to spot.

Thanks, I will check that out ASAP. My previous GMT400 truck (a 2000 K3500) also had a (single) clunk on takeoff. Never bothered to check it out because I thought it was a normal part of owning these trucks. I sold it, and a few months later, the guy who bought it said the driveshaft fell out while he was driving. No injuries or major damage, thankfully, but scary just the same.

 

[HotWheelsBurban]

Thanks, I will check that out ASAP. My previous GMT400 truck (a 2000 K3500) also had a (single) clunk on takeoff. Never bothered to check it out because I thought it was a normal part of owning these trucks. I sold it, and a few months later, the guy who bought it said the driveshaft fell out while he was driving. No injuries or major damage, thankfully, but scary just the same.

When I joints went bad on the Burb, there was a lot more noise and vibration. Got worse with speed so we drove it slowly to a shop where they fixed it. Original joints and they were toast.