Rear end clunking noise

02suburbanZ71 · January 3, 2015

Sounds like removing 50% of the TM via a tune corrects it.

75% will be noticeable but wont correct it

Ron.s · January 7, 2015

The problem is most likely the slip yoke. It appears that GM has really sloppy tolerances on these parts and if your truck has a bad case of tolerance stack up (i.e. smallest spline diameter on the yoke and the largest permissible yoke opening, then you will have a very clunky vehicle. It is really luck of the draw. There was a rumor that GM had a fix for this problem years ago and that they were installing nickel plated yokes on troublesome vehicles. I am not sure if this was real or only a rumor. Supposedly the nickel plating reduced the sloppiness of the yoke fit and made the trucks quieter.

Bingo, there are other causes but I'll bet the slip yoke covers a lot of them. My 2014 Denali is about a year old. Went to the dealer and got the "normal tolerances for parts" can cause the clunking story. Not to worry won't affect performance. GM had a one page bulletin explaining in great detail. After another couple months mine would freeze up overnight and it felt like I had slipped a cog when I started to drive it. Went to a mechanic and he referred me to a top Drive Line shop that took all of 3 minutes to diagnose the issue with the slip yoke splines. He said that they have been an issue for years and two solutions...1. Clean and use a special grease-works most of the time but maybe not a permanent fix. 2. If you can't get warranty then replace the spline section with a quality stainless aftermarket. I had him try #1 last August and spent $80 for what I thought was a cure. Now 5 months later I'm starting to get some minor sticking-usually when cold or after extended use when I'm sure the parts warm up and expand. The intermittent nature is evidence it's the splines and not gear tolerances. Just returned from the dealer today after attempting to get the splines replaced only to get a new service bulletin dated Nov 18 2014...#99-04-20-0021 titled "Information on Driveline Clunk Noise" Lengthy justification for not fixing the problem...citing normal gear lash and tolerances throughout the drive train. I couldn't get the dealer to consider that the splines were sticking because they have no service bulletin on splines and the clunk fits the GM service bulletin. They say GM won't approve repair. I'm going to wait a few months until the issue gets worse and then demand in writing that they repair it or take it to the Driveline shop and get it fixed-then to small claims court for reimbursement. This must be a big issue to get 2 different Service Bulletins in one year. I blame the dealer a little but understand their position. I also understand GM's position but will not live with this issue much longer. Whatever you do don't refer to clunking noise if you take your rig to a dealer. That pulls up the GM Service Bulletin and it's up hill from there. If I had it to do over I would not have had it fixed on my dime but would have gone back to the dealer while it was at it's worst, and I'm now informed on the issue.

davidegl · January 8, 2015

Bingo, there are other causes but I'll bet the slip yoke covers a lot of them. My 2014 Denali is about a year old. Went to the dealer and got the "normal tolerances for parts" can cause the clunking story. Not to worry won't affect performance. GM had a one page bulletin explaining in great detail. After another couple months mine would freeze up overnight and it felt like I had slipped a cog when I started to drive it. Went to a mechanic and he referred me to a top Drive Line shop that took all of 3 minutes to diagnose the issue with the slip yoke splines. He said that they have been an issue for years and two solutions...1. Clean and use a special grease-works most of the time but maybe not a permanent fix. 2. If you can't get warranty then replace the spline section with a quality stainless aftermarket. I had him try #1 last August and spent $80 for what I thought was a cure. Now 5 months later I'm starting to get some minor sticking-usually when cold or after extended use when I'm sure the parts warm up and expand. The intermittent nature is evidence it's the splines and not gear tolerances. Just returned from the dealer today after attempting to get the splines replaced only to get a new service bulletin dated Nov 18 2014...#99-04-20-0021 titled "Information on Driveline Clunk Noise" Lengthy justification for not fixing the problem...citing normal gear lash and tolerances throughout the drive train. I couldn't get the dealer to consider that the splines were sticking because they have no service bulletin on splines and the clunk fits the GM service bulletin. They say GM won't approve repair. I'm going to wait a few months until the issue gets worse and then demand in writing that they repair it or take it to the Driveline shop and get it fixed-then to small claims court for reimbursement. This must be a big issue to get 2 different Service Bulletins in one year. I blame the dealer a little but understand their position. I also understand GM's position but will not live with this issue much longer. Whatever you do don't refer to clunking noise if you take your rig to a dealer. That pulls up the GM Service Bulletin and it's up hill from there. If I had it to do over I would not have had it fixed on my dime but would have gone back to the dealer while it was at it's worst, and I'm now informed on the issue.

I'm probably missing something obvious but what benefit should I expect to gain by not referring to the clunking noise with my dealer?

Ron.s · January 9, 2015

I'm probably missing something obvious but what benefit should I expect to gain by not referring to the clunking noise with my dealer?

Like I said.... clunking noise=gear lash=normal condition=no repair. GM service techs first look at GM bulletins to see if your issue matches a known problem. Not all techs are equal in ability and GM doesn't cover a dealerships cost to diagnose an issue that a service bulletin says is normal. Good luck getting a repair if you walk in to a large dealership and say there is a "clunk" in the rear end.

If it's the slip yoke then you need to do some self evaluation and point the tech to "slip yoke sticking" as the problem. A good driveline shop is a start, that's what they do. If you are like many truck owners you will suspect the slip yoke simply by the inconsistency. Mine started sticking in the AM backing out of the garage; OK for a while and then worse after warm up of a few miles; progressively worse now than new; compared to other vehicles?

Newm · January 9, 2015

Bingo, there are other causes but I'll bet the slip yoke covers a lot of them. My 2014 Denali is about a year old. Went to the dealer and got the "normal tolerances for parts" can cause the clunking story. Not to worry won't affect performance. GM had a one page bulletin explaining in great detail. After another couple months mine would freeze up overnight and it felt like I had slipped a cog when I started to drive it. Went to a mechanic and he referred me to a top Drive Line shop that took all of 3 minutes to diagnose the issue with the slip yoke splines. He said that they have been an issue for years and two solutions...1. Clean and use a special grease-works most of the time but maybe not a permanent fix. 2. If you can't get warranty then replace the spline section with a quality stainless aftermarket. I had him try #1 last August and spent $80 for what I thought was a cure. Now 5 months later I'm starting to get some minor sticking-usually when cold or after extended use when I'm sure the parts warm up and expand. The intermittent nature is evidence it's the splines and not gear tolerances. Just returned from the dealer today after attempting to get the splines replaced only to get a new service bulletin dated Nov 18 2014...#99-04-20-0021 titled "Information on Driveline Clunk Noise" Lengthy justification for not fixing the problem...citing normal gear lash and tolerances throughout the drive train. I couldn't get the dealer to consider that the splines were sticking because they have no service bulletin on splines and the clunk fits the GM service bulletin. They say GM won't approve repair. I'm going to wait a few months until the issue gets worse and then demand in writing that they repair it or take it to the Driveline shop and get it fixed-then to small claims court for reimbursement. This must be a big issue to get 2 different Service Bulletins in one year. I blame the dealer a little but understand their position. I also understand GM's position but will not live with this issue much longer. Whatever you do don't refer to clunking noise if you take your rig to a dealer. That pulls up the GM Service Bulletin and it's up hill from there. If I had it to do over I would not have had it fixed on my dime but would have gone back to the dealer while it was at it's worst, and I'm now informed on the issue.

Did he by chance give you an estimate on what the #2 option might be? Thanks

EXSlider400 · January 9, 2015

The GM nickel plated ones were like $400 for previous models..and they to eventually wore out. Try filling 2wd splines with Lucas red and tacky #2 or really good marine grease. on 4wd you can't use grease but supposed to use atf. ..which won't do anything. the only fix I know for a 4wd is a slip yoke eliminator or a stainless yolk (I don't know where to buy it though).

Mine only clunks at low rpm at low speeds...not from dead stop so unsure if it is the old slip yoke issue or TM...but could be one or a combination of both.

Edited January 9, 2015 by EXSlider400

tduff · January 10, 2015

I'm having the exact same problem. Most noticeable when applying gas after the truck has been coasting for a second.

The "Clunk" or "Thud" is becoming more and more noticeable and feels like bad u-joints to me.

A trip to the dealer is the last thing I have time for at the moment.

My noise is exactly how LS 1st GEN describes. I'd make time for the trip to the dealer. They'll probably say they can't reproduce it but at least it'll be documented.

I just bought a 2014 sierra 1500 4.3/v6 reg cab/reg bed.

has less than 500 miles on it and ....

I am getting the exact same sound!! I,too, took the mechanic with me to duplicate the noise. it sounds just like a defective u joint!! on acceleration and deceleration. also... when coasting down a hill I get the repeating knocking noise.

they did not tell me it is normall, but, rather kept the truck for 2 days until the gmc tech rep sohowed up. it has been identified as a faulty baffle in the muffler/exhaust system. a new muffler /exhaust system is on order and being installed next week.

the tech rep. told us there is a bulletin out on this issue for 2014 sierra's.

after I get the new muffler installed..... will let you know the outcome.

>>>although the gmc technical representative identified the noise as a muffler/exhaust issue.... I still think it's connected to the u joint/drive shaft area.

the mechanic told me they had some 2014 sierra's sl's that needed to have the driveshaft/u joints replaced and noise went away.

First post here...I purchased my 2014 GMC Sierra SLT in October 2014 and have had this same issue. The service advisor at my dealer went for a ride with me and said he had another customer had the same claims of the rear end noise. After reproducing the noise for him he thought it was the exhaust system...I thought he was wrong as it sounded like gears grinding at times. They replaced the entire exhaust system on my truck and it has been noise-free ever since. I talked to the service advisor today and after replacing the exhaust system on the other customer's truck, he said the guy told him that he no longer has the rear end noise either.

To those of you still experiencing this issue, please have your dealer check the Julian date on your muffler to see if your vehicle is covered by the TSB.

I would have sworn the noise was in the drive line or rear end and several buddies said the same thing. I didn't believe the dealer when he told me it was his opinion that it may be the exhaust system...turns out he was right in my case.

Ron.s · January 10, 2015

Did he by chance give you an estimate on what the #2 option might be? Thanks

Don't remember....maybe $480?

Mine made a clunk at times but you could also "feel the slop". When the yoke splines stick, then the release feels like slop in the drive train. You should easily notice the difference between a clunking noise and real movement.

Edited January 10, 2015 by Ron.s

Snowmobiling · February 3, 2015

My truck has been having the same issues with the "Clunk". I've been to 2 different dealerships and they both told me it was normal. Thanks for the support GM!!I paid over $50k for my truck and I'm currently in the market for a new car for my wife. I was thinking about the new Tahoe's, but I'm afraid I'll have the same problems with the drive train.

georgedrauton · February 3, 2015

My truck has been at the dealership for 7 days now, and they are telling me the same thing, that it's normal and the vehicle is functioning as designed. I have contacted a lawyer and if it is not fixed when I get it back I will be filing a formal complaint with GM first, and then with the state Attorney General. Anything that adversely affects the resale value, in the first year and is not fixed within 3 visits or 15 days in the shop, is covered under the lemon law, and must be repaired or bought back by the company... At least in my state. There is no way I would be able to sell my truck for what it's worth with that clunk occurring. And I am not going to just accept that this defect is "normal". GM is going to have a lot to prove to me before I will consider buying another one of their vehicles.

Edited February 3, 2015 by georgedrauton

pm26 · February 3, 2015

The GM nickel plated ones were like $400 for previous models..and they to eventually wore out. Try filling 2wd splines with Lucas red and tacky #2 or really good marine grease. on 4wd you can't use grease but supposed to use atf. ..which won't do anything. the only fix I know for a 4wd is a slip yoke eliminator or a stainless yolk (I don't know where to buy it though).

Mine only clunks at low rpm at low speeds...not from dead stop so unsure if it is the old slip yoke issue or TM...but could be one or a combination of both.

Is that from a stainless egg?

jack s. · February 15, 2015

I've had the same issue from day one. I pointed the noise out to the salesman when I test drove and he said, "its the just the differential", I was so eager to get a vehicle I didn't ask enough questions about it and should not have got the truck. Im sure it would be a problem if I tried to sell it. Mine is a 2013 1500sle, 4wd, purchased in august of 2013 now has 9,000 miles. I never believe a word a service tech or especially a salesman says, will I ever wise up? Should have got a Ford or Tundra. I don't think I have the stomach to take it to a dealership, and I wish I could believe it was the muffler system but that's a tough one to swallow, but glad it relsoved the gentlemans issue in the #52 post. Has anyone else had the muffler system replaced for the "clucking" noise. Mine is as many have described. Almost seems more noticeable when the vehicle is cold, but not certain of that. GM ...lets see will I feel better if I cuss on this post? $41,500 MSRP for this? Gov't Motors, ugh.