2020 1500 Sierra rear suspension bottoms out hard

Rene Fink · January 29, 2021

I have a 2020 Sierra 1500 SLT with the X31 off road package that has a rear suspension problem. This truck has only 13000 kms on it and the suspension is getting weaker and weaker. I should mention that the only weight on the box is a tonneau cover so weight is not an issue.

At first the rear suspension started bottoming out on the larger bumps. Now the suspension bottoms out on even the smaller bumps.

I live in Northern Ontario where the roads are notorious for being bad.

I have been buying GM/Chev trucks for 43 years and this is the first time I have any issue like this.

My local dealer has always given me good service but their hands are tied when it comes to warranty at times and this is one of those times.

I took my truck to the dealer last week for service and I asked them to have a look at my rear suspension. When I picked up the truck after they were done I asked about what they found. They said they took a test drive and the truck did not bottom out. The service advisor agreed to go for a drive with me so I could show him how easily it bottoms out.

We only went for a short ride and I was able to give him a demonstration of what it feels like when the truck bottoms out. He said there is nothing that they can do as they said they checked the shocks for leaks or any damage to the springs and everything looked normal. He indicated that at this point there is nothing they can do but he would watch out for any bulletins regarding this issue.

This morning on my 20km ride to work the suspension bottomed out 4 times.

Has anyone else had this issue and did GM do anything about it.

Rene Fink · January 29, 2021

13 minutes ago, Rene Fink said:

I have a 2020 Sierra 1500 SLT with the X31 off road package that has a rear suspension problem. This truck has only 13000 kms on it and the suspension is getting weaker and weaker. I should mention that the only weight on the box is a tonneau cover so weight is not an issue.

At first the rear suspension started bottoming out on the larger bumps. Now the suspension bottoms out on even the smaller bumps.

I live in Northern Ontario where the roads are notorious for being bad so bumps in the road are a way of life here.

I have been buying GM/Chev trucks for 43 years and this is the first time I have any issue like this.

My local dealer has always given me good service but their hands are tied when it comes to warranty at times and this is one of those times.

I took my truck to the dealer last week for service and I asked them to have a look at my rear suspension. When I picked up the truck after they were done I asked about what they found. They said they took a test drive and the truck did not bottom out. The service advisor agreed to go for a drive with me so I could show him how easily it bottoms out.

We only went for a short ride and I was able to give him a demonstration of what it feels like when the truck bottoms out. He said there is nothing that they can do as they said they checked the shocks for leaks or any damage to the springs and everything looked normal. He indicated that at this point there is nothing they can do but he would watch out for any bulletins regarding this issue.

This morning on my 20km ride to work the suspension bottomed out 4 times.

Has anyone else had this issue and did GM do anything about it.

joostan · January 30, 2021

My suspension is really soft too. ‘21 Sierra SLT with X31, 4x4, duramax. After doing a lot of research I’ve learned that every one of our trucks feels this way, and it’s just a poor suspension system. But I am interested to hear if you can get any more information from the dealer about it.

I’m thinking that bilsteins are in my future...

railguy777 · January 30, 2021

Welcome fellow Canadian. I am also from northern Ontario, although not living there now. I have the same model truck as yours but I have not experienced the problem you are having. Hopefully your dealer can do something for you, keep us posted.

CamGTP · January 30, 2021

I don't think people realize how far the suspension would have to travel to smack the bump stops while doing normal driving even on bumpy roads.

You can test this by putting some grease on the bump stop itself and going for a short drive where you think it's bottoming out. If it never touches then it's not doing it and you are dealing with a different issue like the quality of shocks.

KARNUT · January 30, 2021

Something is wrong if that’s happening. I’ve carried weight in my truck for work on off road ROWs never bottom out. Even my truck with 2-4 lowered didn’t bottom out. A very soft suspension would bounce all over I would imagine. Interested in the conclusion here.

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Gangly · February 1, 2021

I'm with the others, the rear of the truck has a significant amount of travel before bottoming out and you would noticeably be staring up at the sky when it happened. Worn out shocks will sometimes make a clunking sound, mine did on the front, and that could be the sound you are hearing.

The suggestion by CamGTP is spot on and grease, or a grease pen on a potential contact surface, work perfectly when trying to diagnose suspension travel issues.

Edited February 1, 2021 by Gangly

Rene Fink · February 17, 2021

On 2/1/2021 at 10:13 AM, Gangly said:

I'm with the others, the rear of the truck has a significant amount of travel before bottoming out and you would noticeably be staring up at the sky when it happened. Worn out shocks will sometimes make a clunking sound, mine did on the front, and that could be the sound you are hearing.

The suggestion by CamGTP is spot on and grease, or a grease pen on a potential contact surface, work perfectly when trying to diagnose suspension travel issues.

I just went under my truck to have a look at my suspension. I have maybe 2 1/2" between my springs and the bump stop. Small wonder I am bottoming out. I have another appointment in the morning to see if they can duplicate my problem. I already "warned" them to not come back after a test drive and tell me they couldn't get the truck to bottom out or that they cant do anything about it. If this does happen, I will make the necessary changes to fix the problem myself and end my streak of buying GM products at 43 years.

BIGDOGx · February 18, 2021

On 1/30/2021 at 11:53 AM, KARNUT said:

Something is wrong if that’s happening. I’ve carried weight in my truck for work on off road ROWs never bottom out. Even my truck with 2-4 lowered didn’t bottom out. A very soft suspension would bounce all over I would imagine. Interested in the conclusion here.

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Yeah i agree, been driving gm trucks for over 30 years now and not once have i had the rear suspension bottom out. I even have hauled over 1,000 pounds of rocks in the bed and was not bottomed out in a s10 never mind a full size.

Rene Fink · February 18, 2021

i just got my truck back from the dealer. They tell me that this is normal for these trucks. They took a similar new truck for the same ride and said the new one is the same. So now, besides contacting GM directly to complain, I am going to install a real suspension under the last GM truck I ever buy.........

Tahoe02 · February 18, 2021

Check the measurements of another truck like yours on the Dealer lot and see if it is the same.

BIGDOGx · February 18, 2021

3 hours ago, Rene Fink said:

i just got my truck back from the dealer. They tell me that this is normal for these trucks. They took a similar new truck for the same ride and said the new one is the same. So now, besides contacting GM directly to complain, I am going to install a real suspension under the last GM truck I ever buy.........

Are you positive it is the rear hitting the bump stops? Is it a bang noise, a clunk as gm trucks have many bangs and clunks that yes sadly is normal.

Rene Fink · February 18, 2021

Oh, its not just a noise. I can feel it in my bones when it hits. There is less than 3 inches of travel so it doesnt take much to take up that space.

aseibel · February 18, 2021

Did you buy the truck brand new?

You've confirmed that your suspension has never been modified, and it has the same geometry as all the other trucks on the lot? Some photos with a tape measure would help.

Silverado4x4 · February 18, 2021

Your dealer said they checked the shocks and there not leaking, just because there not leaking doesn't mean there not bad. You say its getting weaker and weaker that points to the shocks. I wonder if they unbolted the bottom of the shocks and push up on it to see if it pushes up easy.

I looked at my spring pack and I have 2 leaf's and a bottom leaf (3 total) which the bottom leaf is about 1/2" thick and my bump stop is about 3 1/4" from the axle pad.