intermittent clunk in the drive line

[CKENDZIORA]

Ok guys I'm lost/confused I have 2001 silverado 4x4 with 97,000 that intermittently you can feel and hear a thumping noise under your feet/rear end. My initial thought was u joints but it comes and goes and when its doing it if you turn hard right or left it gets noticiably worse. No clunk when you shift or stop either.

Well I went to Auto Zone tonight to get u joints to discover with my Aluminum drive shaft they are not repacable you must get a new drive shaft? A customer who seems to be a regular there said it isn't the u joints its the rear end change the lube the clutches arent locking in right causing this? Neeedless too say Im confused which way to go new drive shaft, change the rear end lube, consume jack daniels????? Seems latley to be an endless money pit oh well, HELP

[2000CAYukon]

Does it only happen when you are turning and go over a small bump? When this happened on my 2000 Yukon, it felt like it was in the front end somewhere. For me, I could feel it turning into my driveway. After reading about that on this forum, I lubed the intermediate steering shaft and it went away.

If you feel it on takeoff, it could be that the slip joint needs some lube.


//2000CAYukon

[CKENDZIORA]

Some times bumpy roads bring it on yes, the steering column has a groan in it when going lock to lock that has been there for a while too? Intermidiate steering shaft? Lube it with what and how? i do not feel the issue on take off or gear shifts during normal driving but to make it fun it's intermittent.

[2000CAYukon]

GM makes a kit to relube the shaft. It has been a few years since I did mine. I took the shaft out (need to be careful not to turn the wheel when the shaft is out) and lubed it on a bench with the kit. Others have had the shaft replaced under warranty but I was happy after it was lubed and the clunking went away.

Do a search in this forum and you will see a lot of posts on this subject.

//2000CAYukon

[MikeD266]

Good lord, someone behind a counter actually told you you couldn't replace u-joints b/c "it was an aluminum shaft" ?

I had to replace my shaft just yesterday b/c someone behind a counter gave me the wrong u-joint and in pressing it in completely trashed the retainer clip channels before realizing that the part was incorrect.

If nothing else, Neapco's u-joint catalog can be found here: http://neapco.com/pdf/2007universaljointcatalog.pdf . And if you're going as far as pulling the shaft and replacing one u-j you may as well do both at the same time.

There apparently IS an issue with aluminum reacting adversely with other metals. Neapco's BF aluminum shaft u-js have a coating they call "Alumiguard" to help negate this. We'll see how it works as I just did both front and rear on the rear shaft...

If you press them in yourself, rent a u-joint press to make the job easier and damage free or at least use the C-clamp and sockets method instead of trying to pound them out/in with a hammer and risk trashing your tube yoke. Make sure that you install the inside retainer clips on the strap-side u-j caps. Makes it at least a little harder for them to slide out since there aren't any stops on the rear diff yokes to prevent this.

One thing I DID learn in this process is that Spicer-authorized distributors sell both end yokes and tube yokes. Nice to know that if you trash a tube yoke on a shaft and can't find one in a bone yard you can at least have a new tube yoke welded on if you want to stick with your aluminum shaft as opposed to switching over to steel.

Unfortunately, I've got nothing as far as the "clunk"...

[CKENDZIORA]

If I do the u joints yes I will do both that would be dumb to do one and not the other. I have to figure out the clunk though I was told if it was a u joint it would do it all the time. I use a vise and sockets are the joints loctitied in on this shaft?

Well I had a new work colleuge hear my plight and said he had a similar issue with a Bravada and it was the rear end it was toast big $$$$ Im getting that sinking feeling in the pit of my stomach! Thing is the Bravada and the truck Im sure have different drive line stuff.

[j cAT]

Originally Posted by CKENDZIORA

If I do the u joints yes I will do both that would be dumb to do one and not the other. I have to figure out the clunk though I was told if it was a u joint it would do it all the time. I use a vise and sockets are the joints loctitied in on this shaft?

Well I had a new work colleuge hear my plight and said he had a similar issue with a Bravada and it was the rear end it was toast big $$$$ Im getting that sinking feeling in the pit of my stomach! Thing is the Bravada and the truck Im sure have different drive line stuff.

with the rear wheels both off the ground ,,,transmission in neutral rotate the shafts check for looseness...if not loose , the U joints are fine..

check the drive shaft spline for looseness both ends.

replacing the [ALL] drive train fluids is important every 30,ooomi..

with the rear diff you must remove the cover and thoughly clean out all the wear debris...many do not do this and then you have to replace the rear diff which is very possible as your componet that is worn..

[CKENDZIORA]

Question for you as 4 wheeel drive is new to me. Does the front shaft spin even though the truck is in 2 wd mode?

So my guess is by your response your thoughts are the Diff is the issue?

[CKENDZIORA]

Originally Posted by CKENDZIORA

Question for you as 4 wheeel drive is new to me. Does the front shaft spin even though the truck is in 2 wd mode?

So my guess is by your response your thoughts are the Diff is the issue here?

Will changing the fluid at this point even fix the problem?

[j cAT]

Originally Posted by CKENDZIORA

Will changing the fluid at this point even fix the problem?

after lifting and inspecting the vehicle report what you found..

If the fluid needs replacing sure it may fix the occational clunk..

my vehicle clunked at 30,ooomi..the dealer replaced the transfercase fluid clunk gone...that was many years ago ...so I replace all these fluids every 30,ooomi no clunks ,,10yrs 125,ooomi...

the rear diff has that drain hole ...this is where the quick lube shops F up your diff by not removing the cover and cleaning the diff/gears/magnet and inspect for proper gear lash ...

report your findings many have had these clunks ..yours sounds like not a major problem.....


normally U joints cause squeeking, vibs,continual clunking...the joints themselves will weep oil/rust etc when failing....

with the alum drive shaft this U joint set up is very long lasting....IF you did not lift your vehicle to cause the U joints to be at an angle which causes them to flex....

[CKENDZIORA]

Originally Posted by j cAT

after lifting and inspecting the vehicle report what you found..

If the fluid needs replacing sure it may fix the occational clunk..

my vehicle clunked at 30,ooomi..the dealer replaced the transfercase fluid clunk gone...that was many years ago ...so I replace all these fluids every 30,ooomi no clunks ,,10yrs 125,ooomi...

the rear diff has that drain hole ...this is where the quick lube shops F up your diff by not removing the cover and cleaning the diff/gears/magnet and inspect for proper gear lash ...

report your findings many have had these clunks ..yours sounds like not a major problem.....


normally U joints cause squeeking, vibs,continual clunking...the joints themselves will weep oil/rust etc when failing....

with the alum drive shaft this U joint set up is very long lasting....IF you did not lift your vehicle to cause the U joints to be at an angle which causes them to flex....

Thanks for the insights- does the front shaft spin in 2 WD or 4 WD only? I may dive in tommorrow to see whats up one other suggestion was the rear Transmission mount i will check that too.

[j cAT]

Originally Posted by CKENDZIORA

Thanks for the insights- does the front shaft spin in 2 WD or 4 WD only? I may dive in tommorrow to see whats up one other suggestion was the rear Transmission mount i will check that too.

I believe this fwd shaft always rotates...but in 2wd it has no loading....

[CKENDZIORA]

ok u joints and transfer case fluid check out, tranmission mount seems ok too I ll have to look at the rear end next i ran out of time.

[j cAT]

Originally Posted by CKENDZIORA

ok u joints and transfer case fluid check out, tranmission mount seems ok too I ll have to look at the rear end next i ran out of time.

you have to lift the rear wheels off the ground then rotate these shafts and check them ..at this time you check the rear diff yoke ..this is where it goes into the diff for wear ...

[CKENDZIORA]

Originally Posted by j cAT

you have to lift the rear wheels off the ground then rotate these shafts and check them ..at this time you check the rear diff yoke ..this is where it goes into the diff for wear ...

We had the truck on a lift we were tugging and pulling etc and didnt see, feel or observe anything unusual. Man i hate intermittent issues that is why I have grey hair.