Clunk When Sudden Lift From Gas Pedal

[big3500]

Hello,

My ‘94 c3500 extended cab dually has a clunk jolt when I let go of the gas. No matter what gear or speed. I already replaced the motor and transmission mount.

Can you think of anything else that might be producing this?

Thank you in advance.

 

[wirlybird]

My first thought is U-joints.

 

[big3500]

My first thought is U-joints.

I have the parts to replace the U-joints and the driveshaft mount bracket. But I wanted to ask in case I am missing something. Thank you @wirlybird. Merry Xmas.

 

[PlayingWithTBI]

My first thought is U-joints.

Hopefully U-joints and/or yoke, not the rear end!

 

[HeavyAsAChevy]

I had a similar issue which ended up my cross member was bent! So bad that my driveshaft was rubbing the cab! We couldn’t figure out how that happened. May dad and I got a 3” steel pipe and used a buttload of leverage to bend it back.

 

[618 Syndicate]

Check the leaf springs/mounts

 

[sewlow]

Check the leaf springs/mounts

My first thought was a universal, too.
Check the U-bolts.
Known for just turning to dust on these trucks. Poorly designed lower plates/brackets. They hold all the road crud.
Then, check the leaf spring center bolts.
This one is not good. Head's rounded from everything else being loose.

...and that red stuff never sleeps.

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