Mystery noise from back end on new 21 Sierra 1500 SLT

im4snow2000 · April 17, 2021

13 hours ago, Dogdad said:

My truck is finally going in next week for leaf spring replacements. There is also a bulletin out on this matter..

Thx for posting. The above "cause" doesn't seem right. Definitely don't hear it going over normal road bumps......it's when the truck isn't level. Like noted above, when turning at slow speed and road/truck is pitched at small angle. Seems like it would be bushings on, like noted above, loose u-bolts. As noted, mine has gotten worse with more miles (at 3800 miles now, all on-road and essentially clean roads).

intimidator01238 · April 17, 2021

On 4/6/2021 at 6:08 PM, Dogdad said:

Found out today that the thumping noise is indeed the leaf springs. Took a whopping 10 seconds of riding with a service manager for him to know what it was. They wrote up a ticket, ordered the springs, and will call me when they come in. The guy was great and professional. He said they are seeing issues with the new trucks and the whole leaf spring has to be replaced.

Do they have any answer as to what’s wrong with them? Just bought mine 3 weeks ago and noticed the same noise. When I get under it and have someone rock it the noise sounds like it’s coming from either the front bushings or the rebound clamps. I have the max trailering package. I’m wondering if this is an issue with all their springs.

Dogdad · April 17, 2021

9 minutes ago, intimidator01238 said:

Do they have any answer as to what’s wrong with them? Just bought mine 3 weeks ago and noticed the same noise. When I get under it and have someone rock it the noise sounds like it’s coming from either the front bushings or the rebound clamps. I have the max trailering package. I’m wondering if this is an issue with all their springs.

Did you see the post above with GM bulletin notice in regards to this. The shop foreman at my dealership will be working on mine himself and said just replacing the bushings does not fix the issue. So he ordered the whole package to replace mine. Tuesday is the lucky day to get fixed.

intimidator01238 · April 17, 2021

9 minutes ago, Dogdad said:

Did you see the post above with GM bulletin notice in regards to this. The shop foreman at my dealership will be working on mine himself and said just replacing the bushings does not fix the issue. So he ordered the whole package to replace mine. Tuesday is the lucky day to get fixed.

I did see that bulletin. I noticed it on mine with like 300 miles while backing in my driveway. I haven’t been out in any bad weather so it’s not debris and wouldn’t think the ubolts are loose. I was going to torque them for the heck of it but didn’t get a chance. There’s definitely play somewhere in the springs that’s causing it. Let us know how you make out with yours.

im4snow2000 · April 18, 2021

13 hours ago, intimidator01238 said:

I did see that bulletin. I noticed it on mine with like 300 miles while backing in my driveway. I haven’t been out in any bad weather so it’s not debris and wouldn’t think the ubolts are loose. I was going to torque them for the heck of it but didn’t get a chance. There’s definitely play somewhere in the springs that’s causing it. Let us know how you make out with yours.

I don't hear it when the truck's level, going over a speed bump at slow speeds, for example. But as you noted, when turning at slow speeds into driveway, which often throws the truck slightly out of level if the driveway starts an incline from the road, is when I hear it. I would think if it were the Ubolts, I would hear it over all bumps, not just when turning.

Metz54 · April 19, 2021

I think mine just started making this same noise in that last 1500 miles; I notice it the most backing into a parking spot. Like most things that have popped up on this truck it is still intermittent, so I wonder how the dealer response will be.

intimidator01238 · April 21, 2021

On 4/17/2021 at 5:42 PM, Dogdad said:

Did you see the post above with GM bulletin notice in regards to this. The shop foreman at my dealership will be working on mine himself and said just replacing the bushings does not fix the issue. So he ordered the whole package to replace mine. Tuesday is the lucky day to get fixed.

Did they put your new leafs on?

Dogdad · April 21, 2021

They did today. No more thumping noise. Took about 2 hours.

intimidator01238 · April 21, 2021

20 hours ago, Dogdad said:

They did today. No more thumping noise. Took about 2 hours.

That’s good news! Hope it stays that way

im4snow2000 · April 25, 2021

See my 4/25/21 post in the below thread for my solution to the mystery noise.

Dogdad · April 29, 2021

On 4/21/2021 at 6:40 PM, intimidator01238 said:

That’s good news! Hope it stays that way

Well, it didn’t last long. Thumping noise is back as before after new leaf springs installed. This is a problem that GMC needs to get resolved.

Edited April 30, 2021 by Dogdad

GeorgiaRST · April 30, 2021

10 hours ago, Dogdad said:

Well, it didn’t last long. Thumping noise is back as before after new leaf springs installed. This is a problem that GMC needs to get resolved.

At least they are attempting to fix it. The dealers here in Georgia won’t even try to at this point. Still very frustrating and not something you should be experiencing with a new truck.

Edited April 30, 2021 by GeorgiaRST

intimidator01238 · May 5, 2021

On 4/29/2021 at 7:54 PM, Dogdad said:

Well, it didn’t last long. Thumping noise is back as before after new leaf springs installed. This is a problem that GMC needs to get resolved.

That’s sucks, sorry to hear. I’m thinking to try the rubber between the leaf suggestion or maybe even put some spring clamps on that front section. Total bs though to have to do anything with a 60k plus truck with 500 miles on it.

Edited May 5, 2021 by intimidator01238

Dogdad · May 5, 2021

Ok…bought the “Spring Thing” rubber spacer kit. I don’t have a jack or jack stands so I had my dealership install them . They work fantastic. No more noise at all. The shop foreman actually did it for me. He said their dealership actually had been putting rubber bushings they made a couple of years ago and it solved everyone’s clumping noise. However, GMC came down on them and said to quit doing it and they stopped paying the dealership for the install. GMC is putting these cheap plastic spacers in that don’t work. He said it’s only a bandaid fix. So, I recommend these rubber SPRING THING. Easy install . There’s a video on their website showing it. Here’s mine installed.

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Dogdad · May 5, 2021

18 hours ago, intimidator01238 said:

That’s sucks, sorry to hear. I’m thinking to try the rubber between the leaf suggestion or maybe even put some spring clamps on that front section. Total bs though to have to do anything with a 60k plus truck with 500 miles on it.

Check out my last post. Installed the Spring thing kit. No more clunking sounds finally!!

Edited May 5, 2021 by Dogdad