The Clunk that was Not the Drive Shaft Slip Yoke - Solved

[denalianyone]

I've had a clunk in my 07 Yukon XL Denali, since I bought it as-new-to-me, and I have finally solved it.

Whenever I was stopped and pushed the accelerator pedal, I would hear/feel a clunk somewhere under my seat. Similarly, whenever I was slowing down, and the transmission downshifted, I would hear/feel the same clunk. I went out of my way to avoid the situations that led to the clunk, so as not to create any potential further damage, until I found out the source of the clunk.

I had thought that the cause of the clunk was the drive shaft slip yoke, as suggested by members of this Forum. As such, I purchased a new nickel plated slip yoke and two new universal joints for that drive shaft, and I had them installed by my local mechanic. Unfortunately, after the installation, the clunk was still there.

Further inspection of the entire drive train and support structure revealed that the bushing assemblies on one of the front differential support mounts were badly worn and required replacement. As such, I had both front differential support mounts and all 4 bushing assemblies replaced. After the installation, the clunk was not longer there.

Our knowledge base for clunk causes and resolutions has been increased.

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Do you have a list of the parts purchased?


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[Joseph Garcia]

Did u replace the rear yoke as well with a nickel plated one?


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I replaced the slip yoke coming out of the final drive to the drive shaft going to the rear wheels.

 

[Joseph Garcia]

Do you have a list of the parts purchased?


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I do not have the part numbers available for the differential support mounts and bushings, as I had those parts replaced by others.

 

[denalianyone]

I replaced the slip yoke coming out of the final drive to the drive shaft going to the rear wheels.

Oh ok. I replaced only the front slip yoke going to the front wheels on mine. Was going to change the rear as well to the nickel plated to see if that will cure it.


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[Joseph Garcia]

Oh ok. I replaced only the front slip yoke going to the front wheels on mine. Was going to change the rear as well to the nickel plated to see if that will cure it.


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If you decide to change out the slip yoke of the rear driveshaft, take a photo of the sticker on the rear driveshaft, and discuss it with whomever you use to purchase the new slip yoke. They can cross-reference the numbers on your driveshaft sticker, in order to ensure that you get the correct slip yoke for your truck.

 

[denalianyone]

If you decide to change out the slip yoke of the rear driveshaft, take a photo of the sticker on the rear driveshaft, and discuss it with whomever you use to purchase the new slip yoke. They can cross-reference the numbers on your driveshaft sticker, in order to ensure that you get the correct slip yoke for your truck.

I’m going changed out the rear one with the same nickel plated yoke n u joint I did on the front. It should be the same


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[dman928]

I had the clunk, and it turned out to be motor mounts. It's back, and my mechanic thinks it may be the trans mount. So many clunks.

I'll update when I find the culprit this time.

 

[Rocket Man]

I had the clunk, and it turned out to be motor mounts. It's back, and my mechanic thinks it may be the trans mount. So many clunks.

I'll update when I find the culprit this time.

Probably the motor mounts again unless you used the H2 mounts. Trans mounts never go. IMO.

 

[swathdiver]

I’m going changed out the rear one with the same nickel plated yoke n u joint I did on the front. It should be the same


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The front shaft uses 1344 series u-joint and the rear uses 1350 series. Made this chart a while back for future reference, double check it:

 

[Doubeleive]

Do you have a list of the parts purchased?


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these are the brackets for the front differential, mine were toast
ordered them and had the dealer install, got rid of 95% of the clunk. I can still feel it move when I get on it but it doesn't make a clunk sound anymore