Rear End

Josephhunt27 · July 26, 2006

I'm experiencing some play in the rear axel on my '05 Sierra Crew Cab, which is causing a "thump" every time I make a turn. I took it in to a Big O shop and was told it was normal. I didn't notice this until after I had them machine the rotors.

Is it normal to have some play in the axel? I had them jack the truck up and shook the wheels back and forth and heard the same sound as when I drive.

Thanks.

GM-Tech · July 26, 2006

If the rear wheels are off the ground and you grab one and shove it in and out, you're going to have some play and associated noise. This is NORMAL.

pm26 · July 26, 2006

It is impossible to manufacture a differential without play between gear teeth (backlash). If they built one like that , it would not last very long. The key is to be within the permissible specification. Too much or too little backlash is not good and it will manifest itself either as rapid gear wear or excessive play and /or whining noise in the differential.

Josephhunt27 · July 26, 2006

Thanks for the replies. What is within "specifications"? How is it corrected? The thump is pretty prominent. Thanks.

lesZ71 · July 29, 2006

Thanks for the replies. What is within "specifications"? How is it corrected? The thump is pretty prominent. Thanks.

<{POST_SNAPBACK}>

I have a 2004 Chevrolet Z-71 with just under 20k miles. I am also experiencing a clunking/thumping noise from the rear end. It occurs whenever I am going over uneven surfaces such as speed bumps, entering the driveway, etc. The noise occurs mainly whenever I go over these surfaces at an angle. It also occurs sometimes when going around corners. This noise was not present until about a month ago.

I have taken it to two different dealers and they both have told me that it is due to "free-play" in the rear axle and that this is a normal condition. They also stated that they could not do anything to make the clunk go away.

GM-Tech, I read on this thread where you also stated that this is normal. What concerns me is that the noise was not present until recently and I want to make sure there will be no long term damage to worry about as a result of it. Is this anything more than an annoyance?

GM-Tech · July 29, 2006

GM-Tech, I read on this thread where you also stated that this is normal. What concerns me is that the noise was not present until recently and I want to make sure there will be no long term damage to worry about as a result of it. Is this anything more than an annoyance?

<{POST_SNAPBACK}>

I can only tell you that some freeplay in the axles is normal and if you raise the wheels off the ground and shove the axles in and out, they'll go "clunk clunk." I have NEVER heard this noise while driving under any conditions.

So without knowing what the actual source of the noise is, I can't tell if you if whatever it is is anything more than an annoyance.

lesZ71 · July 29, 2006

When I took it to each dealer, I had the service manager ride with me so that they could know exactly what noise I was talking about and how to create it. After having their respective technicians drive the vechicle, they came back and told me that the noise was normal and was a result of having a semi-floating rear axle.

I have a friend who has a 1999 Z-71 with 115k miles and his does not make this noise. Another friend has a 2002 Z-71 with 56k miles and his does not make this noise either.

I am going to try and find a reputable axle/supsension shop and get them to take a look at it. Thanks for your input!

Norseman · August 8, 2006

Hey guys! My Z71 (153, 000 miles) has started to make that noise that you were describing. I took it to the best drive train shop in town (if there is somthing wrong they can fix it). They said there is a bushing that can be placed close to where the "C" clip goes in and that will eliminate the clunk noise. I'm gettin' it done in a couple of weeks. I'll have more info when I get it done. The guys said it (the noise) was a normal occurrence, but it didn't have to be. Man does it pay to know great mechanic's!!

lesZ71 · August 9, 2006

I just got my truck back today from a third dealer in my area...they also stated that this was a normal condition for these trucks...very frustrating experience to say the least.

Glad to hear that you are having some luck! Let us know how this works for you when you have it done.

billy65 · September 4, 2006

I just got my truck back today from a third dealer in my area...they also stated that this was a normal condition for these trucks...very frustrating experience to say the least.

Glad to hear that you are having some luck! Let us know how this works for you when you have it done.

<{POST_SNAPBACK}>

well fellers with clunks in your rear ends,i have a gmc 2000 z71 that was aggrivating me to curse words every time i turned a corner,stopped and started,backed up or anything,i jacked it up grabbed the rear wheel,pulled it out and pushed it back and it made the noise i had been hearing,iremoved the diff cover measured the distance bewteen the axle end and the pin with a feeler guage and got 35 thousands,i used some old pinion shims in equal thickness behind the c clip and fixed the problem,but the problem is simply wear in the c clips i did this when the parts stores were not open or i would have just replaced the clip ,passenger side was the culprit,driver side was ok...

lesZ71 · October 21, 2006

Well, the noise described above started happening when going around corners at low speeds (<20mph) so I took it back to the dealer. The heard the noise and decided to replace the passenger side axle shaft and c-clip. Unfortunately this has not fixed the problem. This past week, I had some co-workers riding the in the back seat and when the noise occurred while entering a parking lot, both guys indicated that the noise seemed like it was somewhere between the rear axle and the back of the cab. They also said that they felt something in the floorboard...like a quick pop. I have also felt something like a pop in the driver's side floorboard a couple of times and my wife felt something in the passenger floorboard about a week ago. Each time we were either turning a corner or going over an uneven surface. Anyone else experiencing this? Are there any recalls or TSB's on something like this? Could it be my leafs springs flexing and causing a vibration in the frame ?

icecoldtexan · October 22, 2006

Well, the noise described above started happening when going around corners at low speeds (<20mph) so I took it back to the dealer. The heard the noise and decided to replace the passenger side axle shaft and c-clip. Unfortunately this has not fixed the problem. This past week, I had some co-workers riding the in the back seat and when the noise occurred while entering a parking lot, both guys indicated that the noise seemed like it was somewhere between the rear axle and the back of the cab. They also said that they felt something in the floorboard...like a quick pop. I have also felt something like a pop in the driver's side floorboard a couple of times and my wife felt something in the passenger floorboard about a week ago. Each time we were either turning a corner or going over an uneven surface. Anyone else experiencing this? Are there any recalls or TSB's on something like this? Could it be my leafs springs flexing and causing a vibration in the frame ?

<{POST_SNAPBACK}>

I had a noise like you describe on my 2001 2500HD. It was the leafspring isolation pad on the bottom leafspring, it was missing. This spring dosen't touch the others until a load is on the truck, so when driving over a speed bump or into a driveway it would hit the other leafspring and would be a metal on metal clunk. I replaced the isolation pads and the problem went away. GM part number is 15247030 it's a round plastic/rubber pad that attaches to the bottom leafspring, two on each side.

lesZ71 · October 22, 2006

Thanks for the response. I just checked and all four of the isolation pads are still there...two each on the bottom helper spring. I have also checked the tightness of all body mounts and bed mounts that I could find. I also checked to make sure that the leaf spring mounting bolts were tight (at the shackles and the U-bolts holding them on the axle). Again, thanks for the feedback...if you or anyone else had any more suggestions I welcome them. Thanks!

lesZ71 · April 20, 2007

The solution to my rear end clunking noise seems to have been found...got some new leaf springs per a TSB about a month ago and so far everything seems really quiet. More information in the following link...

http://www.gm-trucks.com/forums/index.php?...mp;#entry462788