My 03 2500HD 4x5 lb EC makes a weird popping noise from the rear end. I typically notice it when backing the truck up and the brakes are applied either after a turn (backing into a stall) or just flat out backing up. It never does it outside of that. It sounds/feels like a big clunk and almost like someone kicked the bottom of your truck.

I have had it to the dealers 2 different times now and they seem clueless. They changed out the diff oil and it helped some, however; it still persists. What makes it even more difficult they can't duplicate it. I can't make it happen on command but it does happen atleast once or twice every couple of days. It always happens once the truck has been driven around for a bit never cold.

Truck is pretty much stock outside of a Attitude-Egde, AFE intake, AFE 4" exhaust, new torsion keys, and 285/75/16 Dunlops.

Any ideas?

Pit

Have them clean and re-lube the rear drive line splines. Later! Frank

Maybe be a bad u-joint?

Sometimes when they don't have enougn grease (some come factory underlubed) & then get hot, they "stick" & will make a banging noise (just like you described)

Frank- I already had them replace the seal where the drive shaft enters the trans as well as regrease the splines. That didnt fix that problem but it did the bumping/binding going forwards.

Loki-

I will bring that up at the dealer. I am going to a new dealer this time I have had it with Mark Christopher Chevrolet in CA. I feel like i am getting a run a round.

Frank- I already had them replace the seal where the drive shaft enters the trans as well as regrease the splines. That didnt fix that problem but it did the bumping/binding going forwards.

Loki-

I will bring that up at the dealer. I am going to a new dealer this time I have had it with Mark Christopher Chevrolet in CA. I feel like i am getting a run a round.
Does it happen when changing gears or when rolling??

Is it rythmic and consistent?

Is it a ping or a clunk?

Do you have any vibration at highway speeds or while accelerating?

Does it happen when backing up straight or when turning (like out of a parking space)?

I have expierenced this very same thing for the last couple of days. It happens when I am backing up slowly, when backing into a parking space. It has happened twice for sure that I know. It is exactly as Pit described it, a big clunk. Both times I noticed it I was backing up straight and was going slow. The truck was warm as well, been driving about an hour. I have only noticed it backing up.

Greg

Sounds like a locker problem! GM sells a additive for the rearend fluid its like the old posi additive. when you replace the fluid you add this stuff. I change my fluid every 15-20,000 miles due to the locker cluck!

I have a popping noise come from somewhere behind the cab as well. Only happens when turning. Going forward or backward doesn't matter.<O:p</O:p

It's not the rear drive clunk associated with the driveshaft binding on the yoke. As I lube mine every 5-7k else that issue returns. The yoke binding clearly feels like a bump on stops and starts but has never emitted a noise.

I thought the noise might be from the 1.5" block kit that came off my half ton. I removed the 1.5" block and ubolts and went with a 2.5" block and u-bolts (Superlift# 3816), along with the BFG velvet ride shackles. None of this seemed to help or change the popping.<O:p</O:p

I can say this, when the temperature is below 45 I don't have any popping noise, when the temp is above 45 I start to get some popping from the rear when turning. When the temp is around 70 degree's it seems to be worse or very frequent.

My thing is, how it is that temperature sensitive. Expansion and contraction of dissimilar metals are enough to make it non-noticeable at one temp and very noticeable at just a few degrees difference?

I thought it might be the overload spring slapping the spring pack. Though noise doesn't sound like a slap. I bought rear spring isolators http://www.gmdieseltech.com/store2/cart.php?target=product&action=view&product_id=16222&category_id=248 anyway. Installed them and still have the popping when turning.

I've thought about buying new spring packs for both sides, but would be kinda hot at myself if the packs don't end up being the issue. I'm about at ends rope with it and am growing ohhh so close to letting my dealer diagnose and fix the issue.

Disc brake pads shifting back and forth?

All I have is a hunch currently but don't think it's brake pads, as the noise (popping) happens when turning no matter if I'm off or on the brake. It seems like it's something of larger size.

Any recommendations or ideas? I've thought going over the rear of the chassis, loosen, re-tighten, torque to spec? Shackles, front leaf spring mounts, shock mounts, etc?? Maybe laying a little chassis grease around every possible pivot or movement point? Anyone have a good list of torque specs for stuff like the rear shackles, shocks mounts, etc around the rear of the truck?

If the weather cooperates here I would like to aggressively get to the bottom of this.

Thanks for any insight.

To add. The popping seems to come from the inside track depending on turning direction. The amount of pops heard vary from 1 to around 4 on a single 90 degree turn.

Thanks

I have been away so im playing catch up but I notice mind does it the most when its hot out..NEVER does it when the temps are cold. I feel its either the locker or teh slip yoke is binding. It's annoying as @#$@# and yet when i need to reproduce it at the dealer..the truck makes me look like a fool...(my wife would say thats normal lol). I am waiting for it to get good and warm out so i can prove it. I am happy i am not alone. I definitely don't think its brake pads. THe noise made will snap ur head around if ur near by, down right embarassing. As of this moment I am in a waiting mode :(.

Well well, looky what I found. This is the driver’s side torsion bar setup. At the rear of the cross member looking forward.

http://www.getyasome.net/truck/pics/1.JPG<O:p</O:p


Here’s what it looked like from the front looking back.
<O:p</O:p
http://www.getyasome.net/truck/pics/2.JPG<O:p></O:p>

<O:p</O:p
Now here’s what it looked like after I unloaded the torsion bar as much as possible and with some gentle messaging from my LARGE rubber mallet ):h
<O:p</O:p
http://www.getyasome.net/truck/pics/3.JPG
<O:p</O:p
There is a lip on the edge of these thread key ways, this lip should sit over across the cross member. I do believe this was the culprit, about 99% positive. It was 79 degrees here today and no popping from the suspension what so ever. It’s quiet as a mouse and I like it. :D

derek did this fix your problem?

capone8, Yes sir. Absolutely without a doubt this resolved my problem. Funny thing is all this time I was concentrating on the rear spring pack and ubolts. Noises are so hard to locate, majority of the time they seem to mislead or mask the real culprit.