Mystery noise from back end on new 21 Sierra 1500 SLT

[Dogdad]

So bought the truck last week and noticing a slight  noise like thump thump from the back end . It can be clearly heard when going on the street curb of a driveway . Couldn’t figure it out. This morning a friend and I finally shook the rear tires and it produced the sound. Thought I had a loose tire. So I went to the dealership and of course they couldn’t see it right away and I couldn’t leave it. So I’m going back to my truck and stop to tell a tech. He comes over, shakes the tire  and said wow. Thought it might be the spring. Then he and I go and shake the tires of two other brand new  trucks. They all made the same noise. Just doesn’t sound right. Any idea on where it’s coming from? 

Edited March 27, 2021 by Dogdad
Word change

[im4snow2000]

6 hours ago, Dogdad said:

So bought the truck last week and noticing a slight  noise like thump thump from the back end . It can be clearly heard when going on the street curb of a driveway . Couldn’t figure it out. This morning a friend and I finally shook the rear tires and it produced the sound. Thought I had a loose tire. So I went to the dealership and of course they couldn’t see it right away and I couldn’t leave it. So I’m going back to my truck and stop to tell a tech. He comes over, shakes the tire  and said wow. Thought it might be the spring. Then he and I go and shake the tires of two other brand new  trucks. They all made the same noise. Just doesn’t sound right. Any idea on where it’s coming from? 

I have a '21 1500 Elevation 4x4 and hear "it".  A single thump, seems like when rounding a corner slowly...but only sometimes.  Almost like the weight of something shifting to one side.  I checked the spare tire today and it is secured tightly.   Haven't tried shaking the truck but will try that.  Please keep me posted what you find.  

 

Edit:  My noise also seems to originate from the center, or rear of the truck.  Just shook (side to side) the rear-end of the empty truck with moderate effort and can recreate the noise.  But, will need me under the truck with someone else shaking it to try and uncover the root cause.  Definitely in the rear of the truck.

Edited March 27, 2021 by im4snow2000

[Dogdad]

20 minutes ago, im4snow2000 said:

I have a '21 1500 Elevation 4x4 and hear "it".  A single thump, seems like when rounding a corner slowly...but only sometimes.  Almost like the weight of something shifting to one side.  I checked the spare tire today and it is secured tightly.   Haven't tried shaking the truck but will try that.  Please keep me posted what you find.  

 

Edit:  My noise also seems to originate from the center, or rear of the truck.  Just shook (side to side) the rear-end of the empty truck with moderate effort and can recreate the noise.  But, will need me under the truck with someone else shaking it to try and uncover the root cause.  Definitely in the rear of the truck.

Please post what you find. 

[Dogdad]

On 3/27/2021 at 3:57 PM, im4snow2000 said:

I have a '21 1500 Elevation 4x4 and hear "it".  A single thump, seems like when rounding a corner slowly...but only sometimes.  Almost like the weight of something shifting to one side.  I checked the spare tire today and it is secured tightly.   Haven't tried shaking the truck but will try that.  Please keep me posted what you find.  

 

Edit:  My noise also seems to originate from the center, or rear of the truck.  Just shook (side to side) the rear-end of the empty truck with moderate effort and can recreate the noise.  But, will need me under the truck with someone else shaking it to try and uncover the root cause.  Definitely in the rear of the truck.

So, I believe I have discovered what the mystery thump noise in the rear is. Talking to an ex Chevrolet service manager of several years that now owns his own mechanic shop enlightened me of the issue. The shaking of the truck side to side indeed creates a sound, but it’s not what we’re hearing. Shaking the truck sideways creates  the axle play sound which they all have and is normal. . What we’re  hearing is the leaf springs. I’m told that GMC has a kit to replace the leaf spring bushings . They are aware of this. I’m actually going to my dealer tomorrow morning to discuss this with the service manager there. I’ll post my outcome.

Edited April 5, 2021 by Dogdad
Spelling

[JR09country]

So, I believe I have discovered what the mystery thump noise in the rear is. Talking to an ex Chevrolet service manager of several years that now owns his own mechanic shop enlightened me of the issue. The shaking of the truck side to side indeed creates a sound, but it’s not what we’re hearing. Shaking the truck sideways crests the axle play sound which they all have and is normal. . What we’re  hearing is the leaf springs. I’m told that GMC has a kit to replace the leaf spring bushings . They are aware of this. I’m actually going to my dealer tomorrow morning to discuss this with the service manager there. I’ll post my outcome.

This is correct. My 2019 had the same issue and I used a thin sheet of rubber to place between the leaf springs and the noise went away completely.

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[im4snow2000]

5 hours ago, Dogdad said:

So, I believe I have discovered what the mystery thump noise in the rear is. Talking to an ex Chevrolet service manager of several years that now owns his own mechanic shop enlightened me of the issue. The shaking of the truck side to side indeed creates a sound, but it’s not what we’re hearing. Shaking the truck sideways crests the axle play sound which they all have and is normal. . What we’re  hearing is the leaf springs. I’m told that GMC has a kit to replace the leaf spring bushings . They are aware of this. I’m actually going to my dealer tomorrow morning to discuss this with the service manager there. I’ll post my outcome.

Thank you for your reply.  I have not had a chance to further investigate since this thread started. Please keep me posted on the what you find regarding the leaf spring bushings. 

[Transient]

Only issue I've had from the rear was when my kidnap victim got out of their bonds. Pulled over, adjusted bonds, and started driving again. No more noise.

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[Dogdad]

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. 

[im4snow2000]

2 hours ago, 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. 

Thx for the update

[kmeleon]

Is this the noise I'm hearing from under the rear of the truck whenever I hit a bump in the road? Just noticing it because the weather is turning and windows have been going down. I own a 2021 elevation 5.3

[Dogdad]

On 4/6/2021 at 9:12 PM, kmeleon said:

Is this the noise I'm hearing from under the rear of the truck whenever I hit a bump in the road? Just noticing it because the weather is turning and windows have been going down. I own a 2021 elevation 5.3

The thumping noise I hear is when I go over a bumpy road or driveway curbs at a slow speed. Coming from the back of the truck. 

[Dogdad]

On 4/5/2021 at 3:15 AM, im4snow2000 said:

Thank you for your reply.  I have not had a chance to further investigate since this thread started. Please keep me posted on the what you find regarding the leaf spring bushings. 

Evidently it’s not bushings, but they are replacing the entire leaf springs. 

[BigKev]

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. 

Thank you for posting. I think my brand new 2021 RST is having this issue but only backing up out if the driveway

[im4snow2000]

4 minutes ago, Dogdad said:

Evidently it’s not bushings, but they are replacing the entire leaf springs. 

Thx for the update.  Pls keep us posted on your experience with the new springs.  My truck is just under 4k miles and seems to have gotten worse (essentially didn't hear it for first few miles, now it seems more often).  Have yet to take to dealer. 

[Dogdad]

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