How many people suffer from the infamous GM driveline slack or clunk? It started as just a small but not bad clunk when shifting from park to reverse and drive to reverse. Other than that everything was great. Now, it still clunks when shifting from park to reverse and drive to reverse but now happens when speeding up, slowing down, and of course backing up. This happens all the time now, but the dealer says "it's normal, everything is fine". I don't know what to do, because usually you rely on the dealer to fix these big problems, but they act like it doesn't exist. I heard about spider gears in the differential that wear out and could cause a clunk, but I have not idea how to check. I found a service bulletin that seems to discuss this problem but the latest version of this just says to disregard the issue. Here is the earlier bulletin that actually says what to do, it's from 2005: http://ww2.justanswer.com/uploads/he..._Slip_Yoke.pdf

Could this fix my problem, or could it be something else?
Thanks in advance.
2003 HUMMER H2

 

are you mechanically inclined enough to check your u-joints? or know someone who can?

 

Well, if I remember correctly, to check the U-Joints I should put the truck on level ground, put it in neutral, WITH the emergency brake on, then crawl underneath and try to twist the driveshaft to see if there is any movement from the U Joints. Am I close? If so, then yes I can check them myself.

 

great....

you should be able to spot other things potentially wrong as well.... you can inspect the yoke, and the front and rear shafts... make sure your mounts are in place.... look solid... etc...

 

and silly as it might sound... because I can't hear the clunk... make sure your exhaust hangers are intact....

 

The exhaust hangers are intact, the yoke looks fine I guess, I mean it looks polished around the part that goes into the case. The front and rear shafts have a little surface rust but that's it, and all the mounts are solid and don't seem to be worn out. The U Joints actually seem tight, I checked them today and nothing was moving and they are not worn out. The U Joints are sealed so there is no way to grease them.

 

when you have a sealed joint and it starts to go bad you will see some rust coming out from one of the caps , by hand it can seam tight but under torque
it will move . also if you can trust your wife ,lay beside the truck were you can eye ball the drive shaft , have her shift it from part to drive to rev and look for movement . good luck . mike

 

I agree with Bosch..... if everything looks good... go to the next step. try to isolate the area the sound is coming from.... even if you are not ok being under the H2... at least lay next to it....

 

Sounds like a plan, tomorrow I will crawl underneath and have a look. I'll have my wife start shifting between gears and I will crawl around looking to locate the problem. Just curious, do the differentials ever cause the clunk, like maybe there is a worn part, would that cause this. I read about spider gears in the diff that could possibly wear out? Is that normal or just rare occurrences?

 

anything is possible.... but I doubt it.

The rear locker in the H2 is a pretty large/beefy unit.... it's not some cheap junk GM came up with... it is a tried and true unit. It could go bad...but I'd be shocked.