Clunking Transmission

My 2000 Silverado 2500 with trailer tow package and 6.0 engine has a loud clunk when towing my camper. I have had it to the chevy dealers repeatedly and they tell me they can find nothing wrong...I have consulted a number of after-market garages and transmission shops and they tell me that this is a problem with this transmission. Chevy denies this but it seems that every one I ask says that their transmission does this when they tow, no matter what the weight of the trailer they tow...My truck has very low milage on it because I am afraid to tow with it. It works fine without the trailer in tow...It is well within the tow rating for this truck.....

I am considering replacing the automatic with a manual 6 speed.

Am I being paranoid or is this a characteristic of this transmission to clunk???

    I am certainly not an expert but I have heard from experts that this clunk is actuall the Slip Yoke on the driveshaft. Something about a nickel plated one is available that won't do it. If it is in fact the SY. It doesnt hurt anything and you should load it with grease.

What is the tranny shops justification for claiming a problem with the tranny?  Did they give you a logical explanation?

The only clunking that should be happening in an automatic tranny is the clutch packs engaging or the bands grabbing a clutch drum (but I wouldn't describe either of those events as clunking per se) when you shift into forward or reverse. 

Does it clunk when upshifting? or when you first start out after letting off the brakes?  or when stopping?

It clunks when it shifts gears going up a hill or down a hill when the transmission and the rear end are not in direct line with one another. I have a friend who is a service manager at a crysler jeep dealership.....he states that the other manufacturers have issued tsb's on this very same problem. The solution is to remove the slip yoke and clean the old grease from it and the splines completely. Then there is a special synthetic grease that has to be applied. It appears that the old grease is not letting the yoke slide back and forth on the spline when it is under a heavy load. I am going to spend the money to have it done. It is cheaper than buying a new truck as this is the only thing wrong with this one. And it only does it when I pull my camper. Of coarse it will be a while before I get to test it out as I have a long road trip next month with my camper.....

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...this clunk is actuall the Slip Yoke on the driveshaft...

This is a big discussion on my forum, Diesel Place. Many guys have been scared by this noise and even i have been shaken by it from time to time when unloaded. The slip yoke is 98% surely the cause of the noise. I had a 2004 GMC 6.0 and i have a 2003 Suburban 5.3 that both do this even when pulling my 1500 lb trailer. Moch more noticable when pulling a larger trailer like say my 10,000 lb 30' enclosed snowmobile trailer. Hills make it much more noticable and so does using cruise control. Its nothing that is going to harm your truck so don't go worrying about it too much. There IS a TSB out on it so just mention that it is the slip yoke. A lot of service managers don't pick up on it because they have never been fed the info. The most the can do is re-grease and thats about it.


-- Rick

Don't let em' BS you, my local dealer kept telling me this was normal for my 04' 1500. After many repeated trips and short of threatening them to blast my truck through their service doors and destroy everything in sight they replaced the yoke and the problem magically went away. Now mind you prior to the last trip in I took an electric pencil engraver and made some markings on the yoke so that way I could definitely make sure that it was indeed replaced. Fortunately it was still under warranty and they had to foot the bill, however it still took the grief of many countless trips and pounding to make them do it. This is such a shame that 30,000$ doesn't mean diddly to them. No pun intended but I guess the squeaky wheel does get the grease! or yoke in this case.

I guess I need a little credit guys ...  Q: is it the Slip Yoke?

Well guys, I took my truck to the shop and had the slip yoke removed and cleaned of the old grease. The splines also had to be cleaned and new synthetic grease applied...According to the shops I checked with stated that GM had issued TSB's covering this problem. But unless you say to the dealer Slip Yoke TSB's they will look at you like you have 2 heads.....I work for an auto parts place and a lot of the accounts I deliver to verified that indeed this was the correct solution....

Upon some discussion with my wife and co pilot we determined that as time went on the clunking got worse. So we decided to made this service on a regular basis. It is as cheap as an oil change.

My 06 1500 2WD with 18000 has this "clunking" noise when I come to a stop and as I begin to release any amount of pressure from the brake, I get the clunking sound that seems like the rear end is being jolted out from under the truck.  Am I experiencing the same problem that the TSB will fix?

I hve something similar in a 4WD

I just returned from a trip after have another transmission cooler added to the original auxiliary cooler. I also had the slip yoke removed and the old grease replaced with synthetic grease. I also had the transmission mount replaced. What else could be replaced in this drive train from the transmission back that might be causing this horrific noise... apparently I cannot put an allison transmission in a 2000 truck.....Does anyone know if this transmission swap is possible???????

Will you loose any fluid when the slip yoke is removed? Thanks, James

No, the slip yoke slides onto the splines that come out of the back of the transmission before the universal joints....I have also changed the transmission mount...

Change the transfer case fluid. I did that yesterday and lubed the slip yoke and my klunk/creaky noise went away. If you have the autotrack transfer case make sure to get the autotrack2 fluid. It is a funky blue color.
James

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ORIGINAL: matador

I hve something similar in a 4WD

Is it easy to grease the slip yoke and if so, how?  I have a 2000 silverado and it makes the clunk when I start and stop.  I was told a nickle plated slip yoke would fix it but a dealership wants about $500 to do it and if I can just grease it, I'd rather do that.

I just bought my 07 2500HD 4x4 6.0 and i noticed the exact same thing with it, havent towed my trailer yet but when im on the brakes over bumps it sounds like a drive shaft clang.a big enouhg dip in the road will make it slightly also. ill see what i come up with when i pull my car trailer next weeked, im trying to get some more miles on the truck first.
might be a little rough on it pullin a trailer with only 120 miles.