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Drive Train "clanking"

DTS419

By DTS419
in Ask A GM Technician

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DTS419 Enthusiast

DTS419

Posted
Posted

When I put my truck in reverse (foot on or off brake), I hear a distinctive "clank" noise. It sounds like it's coming from the rear of the truck, but hard to say for sure. I also notice the same noise when I am coasting to a stop with my foot on the break and the truck is downshifting. And sometimes, I hear the same noise when the truck is up shifting if I take my foot off the gas just before the shift. Otherwise, the tranny shifts fine, no slipping or hard shifts, just this audible clanking sound that seems to be happening when the drive train is not loaded in forward motion- like there is some slack somewhere. Am I just hearing the notorious G80 rear, could it be a bad U-joint, or is this a warning sign of a coming tranny or transfer case problem? Or is this noise just normal for a truck with heavy duty off road suspension and drive train? And is there anything that can be done about it if it's nothing serious?

bill190 Enthusiast

bill190

Posted
Posted

Well I would certainly have your U-joints checked just to be safe.

 

As they say, if your "front" U-joint fails, you may go "pole vaulting" into the toolies...

bossier62guy Senior Enthusiast

bossier62guy

Posted
Posted
When I put my truck in reverse (foot on or off brake), I hear a distinctive "clank" noise. It sounds like it's coming from the rear of the truck, but hard to say for sure. I also notice the same noise when I am coasting to a stop with my foot on the break and the truck is downshifting. And sometimes, I hear the same noise when the truck is up shifting if I take my foot off the gas just before the shift. Otherwise, the tranny shifts fine, no slipping or hard shifts, just this audible clanking sound that seems to be happening when the drive train is not loaded in forward motion- like there is some slack somewhere. Am I just hearing the notorious G80 rear, could it be a bad U-joint, or is this a warning sign of a coming tranny or transfer case problem? Or is this noise just normal for a truck with heavy duty off road suspension and drive train? And is there anything that can be done about it if it's nothing serious?

 

Grease your slip yoke and see if you still have the clank....

DTS419 Enthusiast

DTS419

Posted
  • Author
Posted
Grease your slip yoke and see if you still have the clank....

 

What kind of grease? Do I need to pull the drive shaft off to do that?

bossier62guy Senior Enthusiast

bossier62guy

Posted
Posted
Grease your slip yoke and see if you still have the clank....

 

What kind of grease? Do I need to pull the drive shaft off to do that?

 

 

Wheel bearing grease will work, yes....the search function might also yield other tips or solutions if that turns out not to be the problem.

DTS419 Enthusiast

DTS419

Posted
  • Author
Posted
Grease your slip yoke and see if you still have the clank....

 

What kind of grease? Do I need to pull the drive shaft off to do that?

 

 

Wheel bearing grease will work, yes....the search function might also yield other tips or solutions if that turns out not to be the problem.

 

 

After doing some searching, I'm pretty sure my next step in the troubleshooting process should be to grease the yoke...

 

I know what the slip yoke is and how to get it off, but before I go getting grease somewhere it doesn't belong, can someone elaborate on exactly where to put the grease, what kind of grease, and how much?

 

Am I greasing inside the yoke, am I greasing the male splines inside the end of the transfer case where the yoke goes in, or am I greasing the outside of the yoke shaft...?

 

How do I prevent from contaminating the transfer case fluid with grease?

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