clunk upon acceleration

My 2001 1500 silverado 4wd recently has started making a noise in the rear end when i accelerate from a complete stop. At first i thought nothing of it, but now its just getting on my nerves. I thought it was loose u-bolts, but thats not the case. Its kind of like a clunk, but immediatlly goes away. Anyone have this problem?? Also, my steering wheel feels strange when i turn at low speeds, i can feel the noise in my palms...anyone else?? The truck currently has 27,000 miles and is still under warranty.

I´m glad my truck is a 2WD, seems like to much stuff is going on with the 4X4s

Does it clunk when you switch from Drive to Reverse? Or vise versa? Is the noise at low speed turns a groan type of noise? Or like someting is rubbing?

My 2000 Silverado does the same thing. Nobody really seems to KNOW
what the noise is, other than annoying.
I at first thought that I had a sticky rear caliper, but I checked and those are fine. I also thought U-bolts, but those were fine too. It has to be something internally in the rear end, axle assembly.
I know I am not much help, but I just thought I would let you know you are not the only one experiencing this problem.
:banghead:

My 2000 Silverado does the same thing. Nobody really seems to KNOW
what the noise is, other than annoying.
I at first thought that I had a sticky rear caliper, but I checked and those are fine. I also thought U-bolts, but those were fine too. It has to be something internally in the rear end, axle assembly.
I know I am not much help, but I just thought I would let you know you are not the only one experiencing this problem.
:banghead:

Your problem is in the differential carrier, the pinion shaft has worn so much that it has slop in it. Don't mistake the pinion gear for the pinion shaft (two totally different parts). The pinion shaft is the large pin that holds the cluster gears inside the carrier unit. It runs through the thrust block and keeps the axle C-clips from falling out as well. Even if you have low miles on truck, check it out or your diff. will evenuatley snap in half. Then you got a whole lot of repairs on top of the diff. Like ring and pinion gears all new bearings/ races, so don't wait! take the rearend cover off and inspect it.

My '02 does the same thing it also clunks when I shift from park to reverse or reverse to drive. Is that the same problem if so, is there any way you can elaborate a litte more on the corrective actions? Thanks

Well the rear differential consist of a carrier (the diff itself) with a ring gear mounted on the left side of carrier, it meshes with a pinion gear and the other end is the yoke(this is the end that your driveshaft u-joint hooks to). A few things can cause slop in the unit, backlash, pinion depth, bearing wear. I have found that the gov-loc differential's fail inside the diff. There are alot of moving parts inside diff. The crossshaft or pinion shaft (nothing to do with pinion gear) starts to oval the seat holes in the carrier housing. Eventuatly a complete snap in half of carrier housing, which has a chain reaction. The ring gear is alot harder metal, and since it was bolted to carrier, now it chews and grinds everthing in the rear axle housing. It can also destroy the axle housing itself if your going fast when it snaps. luckly it will probally happen on a right turn, which u won't be going 40 mph +.Take off driveshaft and rotate rearend yoke see how much play is in the rear diff. (dont jack up tires for this test) you want the load on axle for this procedure. I can go on and on about this, but lets take it 1 step at a time.

My 2001 1500 silverado 4wd recently has started making a noise in the rear end when i accelerate from a complete stop. At first i thought nothing of it, but now its just getting on my nerves. I thought it was loose u-bolts, but thats not the case. Its kind of like a clunk, but immediatlly goes away. Anyone have this problem?? Also, my steering wheel feels strange when i turn at low speeds, i can feel the noise in my palms...anyone else?? The truck currently has 27,000 miles and is still under warranty.I think I had the same problem, if it sounds like you are getting a chirp when you take off then It is in the transfer case, it almost sounds like your brake pads are sticking though. My 1999 had the same issue and by changing the transfer case fluid to GM recommended Blue Synthetic(not sure of the exact fluid name) this was resolved. Chevy knows about it but it doesn't seem like they want to do anything about is until after the warrenty period is up and then you pay about $15-$18 per quart for the stuff. Hope this helps!! John

KC Chevy Owner-
What kind of fluid is in the transfer case from the factory??
Where can you get the Blue Sythetic ??
Thanks for the help!!

LT-Z71drvr-
I am having mine changed again right now, I will get it back tomorrow and I will post what the fluid is called at that point. It takes 3 Quarts for the change. I am sure if you went to the local parts store they would know what I am speaking of though.

KC Chevy Owner-
What kind of fluid is in the transfer case from the factory??
Where can you get the Blue Sythetic ??
Thanks for the help!!

It's called Autotrk 3 fluid (light blue in apperance)

Thanks Skipr this should fix the noise lt-z71drvr is hearing.

rut6466541 your problem does not sound like the same thing from what LT-Z71drvr is explaining, I think you either might have U-joint or rear end problems. I jad to have my U-joints replaced already also around 65000.

KC Chevy Owner...is the backlash/slop issue something the shadetree mechanic can tackle? My Haynes manual just says to have it serviced by a mechanic because it is so complex. And how long can I expect to drive around with this condition? I've gone 35,000 miles so far and it certainly did it before i got it.

Honestly if you have driven it that long you have probably already done some damage to the gears. Although not probably to drastic of damage you could reshim the rearend gears and take out the slop in the gears, you might end up with a little bit of a whine in the rearend at that point though. Re shimming the rearend is not extreamly difficult but it can be a little tedious, and if you get them to tight you can cause more damage by binding them up. There is a mylar film that is available that you use to set the lash between the gears that I believe is available at the parts store. This is very thin but quite precise material that you slip between the gears and set your shims accordingly.

As long as you don't have get into pinion depth re-shimming, it's not extremly difficult. But it is more complex then shadetree mechanic cares to deal with. I did my own (complete, w/ pinion bearings,races..everything) Not all that easy, I had to aquire some speacal tools. I like to take on challenging jobs (call it a learning experience, even if you fail). Those pinion races are a bitch and a half to press out and in!

Skipr, You have a very valid point there!! I was not going that far in to it, I have also changed out all of that and it is a bear. I converted a 70 chev from 4:10 to 3:73 and let me tell you it is a lot of work unless you have all of the right tools for the job, just getting the pinion shaft out is a pain. If it involves that I would recommend taking it in to have done, Rreshimming is something, if you are careful, the shadtree mech can do himself.

Hey guys. New on this forum. I have a 2001 silverado 4x4 as well and have the same infamous "clunk" in the rear when starting from a stop. Have read numerous forums on this and have read two sets of service bulletins from GM regarding this matter. One was about the "clunk" being the slip yoke in the rear diff. Guess in 2003 it was changed to a nickel-plated one and solved the problem. My Chev dealer would not replace it and put the "magical grease" they are told to put on it in the serv. bulletin.
This lasted for about 3000 miles with no clunk, then it comes back.
The serv bulletin from GM stated that it creates no long term damage to any components. (Not sure I totally believe that). I have the clunk (obviosly) and also a "chirp" when the truck rear end is torqued from the start of acc. Seems like it comes from the rear right side. Seems to do that at start and at stop. Trying to figure out what the chirp is.
If you guys know about the slip yoke and bulletins, please excuse me with the rambling!

Apparently GM is using a new gear set with a different pitch on the ring and pinion gears. Backlash is suppossed to be set at around .002 to .004 (pretty tight). Synthetic gear oil 75W90 is required. I've been told that setting up the gear set and getting a good pattern is real tricky and beyond the scope outside of dealership shops. (specialized tools). The reason for the gear change was to reduce gear noise from the rear diff.
Supposedly though one can use a gear set from of earlier models if they need replacing and thus be able to do the overhaul yourself.

hey guys, i am a chevy tech and have seen these problems before and have had them on my truck...
the clunk upon acceleration and the clunk/looseness in the steering are both TSB's (technical service bulletins) for the silverados

the clunk on acceleration is the slip yoke on the driveshaft...its the end that slides onto the driveshaft

There is an updated nickel plated slip yoke available and usually we give them a liberal coat of high temp grease on the splines when we reinstall it...
the clunk/looseness in the steering system is the intermediate steering shaft...the bulletin calls for you to lubricate the intermediate shaft or replace it depending on the severity of the knocking and the amount of times its been done previously

hey guys, i am a chevy tech and have seen these problems before and have had them on my truck...
the clunk upon acceleration and the clunk/looseness in the steering are both TSB's (technical service bulletins) for the silverados

the clunk on acceleration is the slip yoke on the driveshaft...its the end that slides onto the driveshaft

There is an updated nickel plated slip yoke available and usually we give them a liberal coat of high temp grease on the splines when we reinstall it...
the clunk/looseness in the steering system is the intermediate steering shaft...the bulletin calls for you to lubricate the intermediate shaft or replace it depending on the severity of the knocking and the amount of times its been done previously


That would explain most cases, but mine was clearly the differential. I confirmed that by taking the rear cover off and watching the millions of little pieces of the carrier and internal componets roll out onto the ground. I see it starting on other peoples silverado's. the pinion shaft (not pinion gear) starts to wear the carrier holes out of round creating alot of slop in the rear. Have you come across this problem? I have seen 2 cases and i'm not a auto mechanic.

hey,
they only cases ive seen having to do with the rear ends are the bearings wear out severly and all the rollers fall out of the bearing and end up in the gear oil...i know there is some sort if bulletin for it but off hand i am not sure what it is...

hey,
they only cases ive seen having to do with the rear ends are the bearings wear out severly and all the rollers fall out of the bearing and end up in the gear oil...i know there is some sort if bulletin for it but off hand i am not sure what it is...


I use Mobil 1 synthectic 75-90W with no additive in my G80, My old one was Sta-lube gl-5 hypoid w/additive. I didn't like sta-lube. What do you think am I using wrong fluid?

is the differential (pinion gears/shaft) work something that a firestone service center can handle or is there a specialized mechanic for this kind of work?

is the differential (pinion gears/shaft) work something that a firestone service center can handle or is there a specialized mechanic for this kind of work?


I would have to say no, it's a speacilized repair. They have shops dedicated to just rear ends..places like J & S Gear. Kind of like transmission shops primarly do just transmissions.

The clunk on accel could possibly be coming from the slip yoke where it goes into the trans. There is a TSB for a special nickle plated slip yoke for certain 4x4 with ext cab and push button 4wd. As for the noise in the steering column, there is also a TSB to replace the steering shaft. These are currently on backorder.

I own a 99 GMC Denali and have the same problem. Apparently, there is no bulletin or nickel plated slip yoke on the problem. THe local GM techs blow me off. (they can't figure it out) Origionally they added lubrication to the slip yoke going to and from the transmission/transfer case. This fixed the problem for about 2 weeks, and @ 8/10 hours labor I decided I was done letting them service my vehicle. So I went back in when it started up again and was informed I should replace my slip yoke, So I replaced my slip yoke and U-Joints at the same time. Before installing the new slip yoke I took a vernier caliper and miced the two. Both where the exact same diameter down to the .0001. I called they said it didn't matter it's worn even though it's not worn :-). yea right, so I took them at their word and replaced. That was 8 months ago and I am still having the same problem. My question to you as a GM technician is this. Any other ideas? any fixes that they won't tell me about? Also There is about .0010 play between the slip yoke and the transfercase/transmission. Would I harm anything from calling the local casting shop and getting my slip yoke nickel plated about .0003 to fix the problem myself? ( about $40.00 is the estimate I'm getting). That would leave appx. .0070 spacing between the plines and the transmission.? If not I would be willing to donate the $40.00 and my truck as a "trial run" to see if this helps. Any help you have would be great. I'm also posting this in the room so if you'de like to respond there maybe this can solve more than just my problem? Thanks in advance for any response.

won a 99 GMC Denali and have the same problem. Apparently, there is no bulletin or nickel plated slip yoke on the problem. THe local GM techs blow me off. (they can't figure it out) Origionally they added lubrication to the slip yoke going to and from the transmission/transfer case. This fixed the problem for about 2 weeks, and @ 8/10 hours labor I decided I was done letting them service my vehicle. So I went back in when it started up again and was informed I should replace my slip yoke, So I replaced my slip yoke and U-Joints at the same time. Before installing the new slip yoke I took a vernier caliper and miced the two. Both where the exact same diameter down to the .0001. I called they said it didn't matter it's worn even though it's not worn :-). yea right, so I took them at their word and replaced. That was 8 months ago and I am still having the same problem. My question to you as a GM technician is this. Any other ideas? any fixes that they won't tell me about? Also There is about .0010 play between the slip yoke and the transfercase/transmission. Would I harm anything from calling the local casting shop and getting my slip yoke nickel plated about .0003 to fix the problem myself? ( about $40.00 is the estimate I'm getting). That would leave appx. .0070 spacing between the plines and the transmission.? If not I would be willing to donate the $40.00 and my truck as a "trial run" to see if this helps. Any help you have would be great. I'm also posting this in the room so if you'de like to respond there maybe this can solve more than just my problem? Thanks in advance for any response.

The only other fix that I have seen is simply the spline lube which only last 2-6 months depending on the environment. As far as nickle plating your yoke, I have never tried it, but I don't see why it wouldn't work.

All,

I have this symptom too. I need a new diff cover anyways so I will change the fluid when I do that next weekend or when it starts to get warmer outside (in NE PA). I am not going to drive the truck again until I get the new fluid/diff cover installed.

Question: Can oversized tires cause this to happen over time? I just bought the truck with 126k miles on it and it had General 285/75-16's on it. I put Firestone 265/75-16 tires on it.

I bought my Silverado @ 72,000 km with the stock 265/75/16's on it which i swapped over to my 255/85/16's at the time of purchace. (dealer did it for free where i traded it in) It now has almost 91,000 km's on it and other than being a little harder on gas and a touch down on power cause of the tire size , i have not had any drive line problems of any kind..................yet

if its a clunk that can sometimes sound like a chirping of a tire, then its the driveshaft yoke.....get the updated yoke or grease the hell out of yours.....if it goes away, great, if not, then id start looking at rebuilding your rear end.

I think I had the same problem, if it sounds like you are getting a chirp when you take off then It is in the transfer case, it almost sounds like your brake pads are sticking though. My 1999 had the same issue and by changing the transfer case fluid to GM recommended Blue Synthetic(not sure of the exact fluid name) this was resolved. Chevy knows about it but it doesn't seem like they want to do anything about is until after the warrenty period is up and then you pay about $15-$18 per quart for the stuff. Hope this helps!! John


Hello, It sounds like you've described the 'groan' or 'chirp' my 2001 Z71 makes (50k miles) after a full stop, then accelerating. From what I've read in the forum, changing the xfer case fluid (using the Blue Synthetic fluid) first might be a good start to getting rid of this noise. Thanks.

Anyone happen to know the TSB number for the nickle plated slip yoke? I printed out a numbered list but don't see anything that actually says "slip yoke".

Thanks

Did anyoe realize that "Tigga" the original postie didnt ever respond to any of your posts!! :lol: thought that was kinda funny, anyway, carry on

Sorry, I can't remember the tsb, but the part numbers for the nickel plated yokes are 12477702 for the 1500 series, and 1247704 for the 2500 series.

I have a 2003 silverado with a 6 inch lift, 3 inch body lift, 315/70/17 tires. Okay I have a CHIRP noise kind of high pitch, this noise is observed when i take off from a stop. It does sound like its coming from the right rear end like the others. ALSO when i pull out of my garage and my back end drops on the slope i hear it then. Sooo what would i check, i thought the transmission mount would fix the problem but no luck, so change to the blue fluid? the nickel yoke? just grease the yoke? HELP Please.

If you are getting a clunk on acceleration it is the slip yoke. You can either grease the pooh out of it, inside on the splines or replace it with a nickel plated slip yoke. DO THIS!! It will take care of the noise.

I tend to disagree with the slip yoke theory. I greased and also have installed the reaquetball fix for the slip yoke. This fixed the "clunk" when shifting from park to drive and from drive to reverse. But I still get a sort slip and clunk when I excelerate from a stop. And it feels and sounds like it is coming from the rear diff.