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Discussion Starter #1
Decided to start a new thread about this... I'd be interested what others experience with this is. There is some more info here:

https://www.dieselplace.com/forum/63-gm-diesel-engines/864-duramax-seventh-generation-2020-l5p/981162-2020-gmc-any-reviews-new-owners.html

I have a 2020 GMC 3500 Denali that has had the steering wheel shake problem since new. It has the factory 20" rims and Crapyear tires. The truck has now been to two different dealers a total four times for resolution of this issue. It seems to be fairly widespread - I drove 4 other identical trucks, and they all had the issue to some degree. Mine was still the worst. It is most noticeable when is there is slight pressure on either side of steering center, like when correcting for road crown, although even on straight center there is still a discernible shake in the steering wheel.

To date, one tire has been replaced (sidewall bulge, not related), all four tires have been balanced and road forced six times, and the wheels swapped front to rear, side to side, etc. The software update was applied (Bulletin #19-NA-240, N192279900), which helped to some degree, however all it does is increase the steering effort, which masks some of the vibration, and tightens up the centering of the steering box.

GM TAC has told the dealer there is no fix for the problem, and they will no longer pay any more warranty claims on my truck for this issue. They are now saying that this is a "normal" condition. The latest dealer has been great, but they are done, as there is nothing left they can do.

GMC Executive Care team has been working with both me and the dealer to try to figure something out. I was contacted yesterday and informed that GM engineering is working "overtime" on finding both the cause and the fix. They have determined that although some tires minimize the issue, it is NOT a tire problem that is causing it, and replacing the tires does not represent either a true fix, or a long term solution. I'm not going to dispute that many have found this to work - just relaying what GM has told me.

I take all this to mean that there is a unsprung weight issue with the 20" wheel / tire combo, there is an inherent balance flaw in the stock 20" rims, or a problem with geometry within the steering/ suspension on the Denali and High Country models. The steering wheel shake is not affecting the ATs with 18" wheels.


Ultimately, I have concerns that GM can't fix this issue, and more so what the long term damage may be to the steering and front suspension because of the constant vibration. I love this truck, but when my hands were literally shaking after a 300 mile drive because of the constant vibration, I think its about time to think about other options.
 

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I would try an alternate set of wheels and tires.
If there is a casting defect within the wheels, rotating them is not going to remedy the shake.
 

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Discussion Starter #3
I would try an alternate set of wheels and tires.
If there is a casting defect within the wheels, rotating them is not going to remedy the shake.

Thanks - Dealer #2 tried a set of Denali take offs, and another set from a truck with 15 miles on it. No difference.
 
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You stated that the 18" AT equipped trucks aren't affected? When the dealer tried other wheels and tires, was a set of the 18" tried?
 

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Discussion Starter #5
You stated that the 18" AT equipped trucks aren't affected? When the dealer tried other wheels and tires, was a set of the 18" tried?
Neither dealer had one when my truck was there to try. But both had not had any problems reported with the 18" ATs. The second dealer said he'd try the 18s, but I'd have to pay for the labor since he can't warranty anything more on my truck per GM TAC. I told him I'd consider it and to let me know when they get a suitable "donor" truck.

One of the sets they did try had Michelin LTXs. The steering shake was better, but still pretty evident. At this point I am tending to agree with GM that it isn't entirely a tire problem, although the Crapyears are notorious for balance problems and high road force issues. The road force on mine were all below 30 lbs though.

However, there are hundreds of posts across the various forums about problems with the 20" set up, and I've seen none about anyone with the 18" wheels having this problem.

Before I bought my Denali I test drove a 2500 AT with the same Crapyear tires but 18" wheels and the steering felt entirely different, and not a hint of any vibration whatsoever.
 

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That really sucks your having issues with your new ride. I talked with two contractors today that are doing work for us, both have 2020 3500 gmc’s with the 20” wheels With Goodyear tires, and both said they do not have any shake, but they do not have denali’s. Hopefully you can get it figured and gm steps up. Do you have the heavy duty front springs?
 

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Discussion Starter #7
Mine doesn't have the heavy duty front suspension according to the RPO list on the door jamb. Still have heard not one word from GM despite promises of a fix, and GM TAC isn't even calling the dealer back.
Pretty frustrating to say the least.
 

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I'd like to see the alignment spec, especially toe.
A zero toe condition can cause a wander "wag".
Can you describe the vibration better?
In the steering wheel only?
Does it feel side to side?
At what specific speeds?
And, while it is felt in the front, I'd like to see the results of reclocking the outer rear wheels (so both stems are near, not opposite.)
 

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Discussion Starter #9 (Edited)
I'd like to see the alignment spec, especially toe.
A zero toe condition can cause a wander "wag".

RO shows 0.15 degrees toe; Camber -0.4; Caster 2.0. Had a pretty good pull to the left and the steering wasn't centered when new. Realignment fixed the pull.

Can you describe the vibration better?

Two things: First - steering wheel "oscillation" (side to side) feels similar to a warped rotor or a tire way out of balance when lightly applying brakes. Definitely feel it when there is slight pressure on the wheel- correcting for road crown for example, and always there. Almost like a buzz. Second - A true death wobble 'light' when crossing bridge expansion joints or RR tracks. Usually corrects itself within a 1/4 mile.

In the steering wheel only? Yes

Does it feel side to side? Yes - steering wheel shakes side to side.

At what specific speeds? 60+

And, while it is felt in the front, I'd like to see the results of reclocking the outer rear wheels (so both stems are near, not opposite.)

Currently within about 15 degrees of each other.

Thanks for any insight.
 

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Can you put rear stems at 180°, give or take?
 

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Discussion Starter #11
Can you put rear stems at 180°, give or take?
I'll try that this weekend.


Should also note that talked to an independent suspension tech last night about the problem. He installs lifts, etc. He told me that every single Denali 3500 he's worked on has the same problems. He's convinced it has to do with the electronic steering assist system AND the design of the factory wheels in combination.


His theory is the wheels are designed with most of the metal mass near the outside edge which gives it a slightly unbalanced side to side weight distribution. There is also a greater offset than the wheels on the AT, which doesn't seem to have this issue. When there is slight lateral pressure on the wheel - like correcting for road crown, the tire tread then is not uniformly loaded, which causes a vibration. He claims the Crapyears have a very stiff sidewall / tread, and that's why some people find that changing to a "softer" tire like Michelin LTXs get improvement.

The electronic assisted steering system detects this vibration, and essentially gets "lost" on whether to apply assist or not. This leads to the system "pulsing" pressure into the steering box, which is felt by the driver. This makes sense to me. The steering wheel oscillation feels no different at 60 or 80, and is a uniform frequency. It also feels slightly like when the lane departure system kicks in on my Traverse. I can feel a very slight vibration just before the steering wheel is forcibly turned to correct lane position.

He has an AT coming in that he will swap wheels with mine, and see if there's a difference. If so, that would give credence to the wheels being part of the problem. His opinion is that until GM figures out a different programming of the electronic assist system, the shake will continue to be present, even if the wheels and tires are changed.


Possibly that's why GM told me not to replace the tires, as that isn't the real fix... all just a theory though.
 

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Discussion Starter #12
Tried rotating one of the rear tires so the valve stems are 180 to each other. No difference at all.

I pulled the fuse for the electronic steering control and viola - the shake is completely gone, and I actually like the steering feel much better. But this seems to validate what the suspension guy told me that it is a problem with the ESC system. Its either calibration or some hardware problem.

Not sure what to do now, other than leave the fuse out and clear the warning message every key cycle.
 

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Tried rotating one of the rear tires so the valve stems are 180 to each other. No difference at all.

I pulled the fuse for the electronic steering control and viola - the shake is completely gone, and I actually like the steering feel much better. But this seems to validate what the suspension guy told me that it is a problem with the ESC system. Its either calibration or some hardware problem.

Not sure what to do now, other than leave the fuse out and clear the warning message every key cycle.
Now that you found something, take it to the Dealer and show them so they can take it up with GM and get a cure going on the issue
 

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Not sure what to do now, other than leave the fuse out and clear the warning message every key cycle.
Just curious what warning message are you getting?
 

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He will have a service steering message when you remove power from ves module. This makes the tbar really soft so it dampens any type of tire or road induced vibration.

It unfortunately does not help the dealer figure out what component(s) have an issue or if the dealer did not follow the service bulletin properly.

Backing off the lash adjustment on the steering gear is properly worth trying. I would mark the adjuster position before moving it. Very small movements go a long way.
 

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Discussion Starter #16 (Edited)
He will have a service steering message when you remove power from ves module. This makes the tbar really soft so it dampens any type of tire or road induced vibration.

It unfortunately does not help the dealer figure out what component(s) have an issue or if the dealer did not follow the service bulletin properly.

Backing off the lash adjustment on the steering gear is properly worth trying. I would mark the adjuster position before moving it. Very small movements go a long way.
That is great information MTU, and I appreciate you reaching out to me here and other venues. You have been way more help than anyone from GM so far. If you do work for GM realize the following rant is NOT directed to you, but to GM as a corporation.

If backing off the lash adjustment is a path towards a fix, then why is GM not communicating this to the dealers. My dealer has been told by GM not to attempt further repairs as they will not get paid for the warranty work. I'm not going to pay them to try this, and the dealer won't anyway because they are not going to be held liable if this messes anything up. Frankly neither I, nor the dealer are in the business of replacing the GM engineering group that should be figuring this out, and then giving direction to the dealer.

My real frustration is over the last five months since I bought this truck, I have been fighting this issue. I have elevated this to the supposed highest level of GMC customer support, who has basically told me this isn't fixable, and live with it. In response to a twitter DM to the official GMC account, I was told to just lemon law the truck - even including a link to do that. Is that what GM has come to?

I, like most everyone else, will be writing a huge check for the next 5 years or so to pay for my truck. To see GM basically turn their back on customers is just not right.

Ok rant over...
 

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What is the "tbar"?
 

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I have elevated this to the supposed highest level of GMC customer support, who has basically told me this isn't fixable, and live with it. In response to a twitter DM to the official GMC account, I was told to just lemon law the truck - even including a link to do that.
Last vehicle we bought the head lights would flicker at night and we were told there was no fix. They couldn’t duplicate it after having it for three weeks so we put a GoPro on the dash to capture it. They did even want to look at it and within 3 months we had a new vehicle. Year newer 15 to 16 and they paid all taxes, transfer et... no cost.
You didn’t pay for something that doesn’t work. That’s what I reminded them off.
 

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Discussion Starter #19
...within 3 months we had a new vehicle. Year newer 15 to 16 and they paid all taxes, transfer et... no cost.
You didn’t pay for something that doesn’t work. That’s what I reminded them off.

I hoping it doesn't come to that. I lemon lawed a truck back in 2006 - it took months for GM to respond, and by the time they did I ended up waiting for another 8 months for the new truck because of the 2007.5 - 2008 transition. I just can't go that long again without a truck - that might have the exact same issue since so many 2020 3500 Denalis seem to have it now.


But it's a real possibility that I do go down that road because even GM is telling me to do that... which is pretty sad.
 

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The steering guys probably don't want dealers to play with lash adjustment in fear of screwing it up and having to replace the gear. There is a special tool that dealer needs to do the adjustment and not sure all dealers have it.

Did we confirm the dealer cleared the offsets/adapts after they reprogrammed the steering module? I heard some dealers have skipped this step.

I just wish I could get my hands on this truck for a couple days to figure what is going on. We have never seen a truck where the service bulletin does not fix it.

#iworkforGM
 
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