2020 L5P Denali Steering Wheel Shake / Wobble - Page 4 - Chevy and GMC Duramax Diesel Forum
2020+ (Non Powertrain) Discussion of 2020+ topics not related to powertrain

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post #31 of 119 (permalink) Old 09-24-2019, 05:33 PM
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Originally Posted by RichieRichZ06 View Post
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Originally Posted by Mtu Alum View Post
This issue has nothing to do with tires. There is a steering calibration coming to fix. Should be available in about two weeks for service.

#iworkforGM
It's a combo of both, but crap tires are definitely the majority of the concern. I have a early built 2020 Silverado 3500 High Country and it shook like a mofo. We've replaced two tires and spent several hours with a field engineer gathering PICO data. After a lot of road force matching tires, swapping corners and a couple new tires, mine is smooth. The field engineer mentioned they have a new calibration coming and we're going to try it on my truck when available. The construction of these GY tires has weird placement of inner ribs on the carcass of the tire. If you happen to get one that has a section with more of the ribs, it's directly related to the area that is measured with high road force. Tires with a more uniform spacing of those internal ribs don't have as high of road force.

We have 2 other High Country 3500's with similar issues. We replaced two tires on one of the trucks, road forced the crap out of the others and drove it 100 miles. One of the new tires we had just replaced tripled in road force and the truck was shaking again. That tire was replaced again and we've been good to go since.

Part of the tire issue is that Goodyear told GM their spec for road force was something like 60 lbs or less and that's what GM was using when assembling the wheels/tires at the factory. In reality these trucks require 20 or less for no shaking. I think the more recently built trucks had that part of the equation fixed at the factory, but the calibration should clean up the rest of it.

My truck now has nearly 6k miles on it and it's been good. I'm just glad because we spent a lot of time "fixing" these $78k trucks before we could even let customers test drive them.
This issue is only happening on trucks with the electric assisted steering not on the base hydraulic trucks. If you have to road force below 20 and less than 0.5 oz then the truck is the issue not the assembly.

At 60 psi, the maximum road force is 45 lbs. At 70 psi, the maximum road force is 50 lbs. At 80 psi, the maximum road is 55 lbs. Road force goes up 7 lbs per 10 psi of pressure.

By making cream puff tires, you are just masking the real issue and giving the smooth road shake software more authority to correct the real issue. As the steering system breaks in, the lash will increase and help dampen this out.

I personally would drop the front tire pressure 10 lbs and continue to drive a couple thousand miles until the cal is available.

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post #32 of 119 (permalink) Old 09-24-2019, 10:20 PM
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I've had smooth sailing since switching tires at 600 miles. I could literally put my phone on the steering wheel recording going down the road to prove a point. I do think these trucks are more sensitive to road conditions, I.E. transferring more road feedback to the driver, which could be seen as both good and bad.

2020 GMC Denali HD 3500 SRW Quicksilver

- Michelin LTX AT2s
- BAK Revolver X4
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post #33 of 119 (permalink) Old 09-25-2019, 06:15 AM
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Originally Posted by Mtu Alum View Post
This issue is only happening on trucks with the electric assisted steering not on the base hydraulic trucks. If you have to road force below 20 and less than 0.5 oz then the truck is the issue not the assembly.

At 60 psi, the maximum road force is 45 lbs. At 70 psi, the maximum road force is 50 lbs. At 80 psi, the maximum road is 55 lbs. Road force goes up 7 lbs per 10 psi of pressure.

By making cream puff tires, you are just masking the real issue and giving the smooth road shake software more authority to correct the real issue. As the steering system breaks in, the lash will increase and help dampen this out.

I personally would drop the front tire pressure 10 lbs and continue to drive a couple thousand miles until the cal is available.

#iworkforGM
Thank you, great explanation. Makes perfect sense

2020 Sierra AT4 3500 Duramax
2018 Denali 2500HD L5P Derringer equipped
2018 Montana 3811MS Legacy 16400#2900pin
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post #34 of 119 (permalink) Old 09-25-2019, 09:27 AM
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Originally Posted by Mtu Alum View Post
This issue is only happening on trucks with the electric assisted steering not on the base hydraulic trucks. If you have to road force below 20 and less than 0.5 oz then the truck is the issue not the assembly.

At 60 psi, the maximum road force is 45 lbs. At 70 psi, the maximum road force is 50 lbs. At 80 psi, the maximum road is 55 lbs. Road force goes up 7 lbs per 10 psi of pressure.

By making cream puff tires, you are just masking the real issue and giving the smooth road shake software more authority to correct the real issue. As the steering system breaks in, the lash will increase and help dampen this out.

I personally would drop the front tire pressure 10 lbs and continue to drive a couple thousand miles until the cal is available.

#iworkforGM
So riddle me this.....

I'd imagine the reason you don't see it on the base trucks is because they don't have 20" wheels with the same tires. We have not witnessed this on any trucks that don't have the 20" Goodyear Trail Runner tires.

If this issue is on all NV8 (electric assist) trucks then why do none of the trucks with 18" wheels have a problem? I ASSume the steering calibration is the same in both trucks (2020 HD LTZ 4x4 with 18" wheels and 2020 HD LTZ/HC 4x4 with 20" wheels) because the steering gear is the same for 2500/3500 HD crew cab with NV8.

Also if you have a LTZ that came with 18" wheels and no shake, but then you swap wheels/tires from a 20" wheel truck with a shake, why does the original truck shake and the truck that you put the 18" wheels/tires on stop shaking?

Lastly, if the calibration is the fix then why are several people reporting that switching to a different brand of tire immediately fixes the vibration without getting the cal updated?

I understand the steering calibration might help some, but the tires are still crap. A couple of these trucks showed up with over 60 pounds of road force that increased as miles were put on the trucks.

GM should've never went back to Goodyear tires and they should still give people the option to upgrade to Michelin tires when ordering the truck, just like in previous years.

The slight shake of just the steering wheel isn't a huge concern of mine now that we got the ridiculous amount of vibration out of it. Now you can see it on the steering wheel, but you can't feel it. However when my truck (and the other 3 LTZ and High Country's) trucks first came in, the vibration shook the entire truck.

The other interesting thing is that lowering the tire pressure actually makes the shake worse. It's totally opposite of everything the field engineer, brand quality and us thought, but it's true. The PICO levels we obtained on my truck were actually worse when I went from 80 PSI to 65 PSI and they got even worse with a few hundred miles on the new tires. We had road force readings on the 2 tires we replaced go from under 20 pounds when we first mounted them to over 60 pounds in ~600 miles of driving the truck. One of them also developed a "thump" noise when spun up on the road force balancer. The thump noise corresponded perfectly to the area of the tire that had an excessive amount of the internal ribs molded into the tire. Even worse is that one of the tires was on the rear and the steering cal won't do a damn thing for a vibration from a rear tire.

I'm not trying to argue, but we've been dealing with this for several weeks and ~30 hours worth of labor so what we've seen (and documented) is slightly different than what engineering, TAC and the "subject matter experts" have been saying.
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post #35 of 119 (permalink) Old 09-26-2019, 04:14 PM
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post #36 of 119 (permalink) Old 09-26-2019, 04:32 PM
 
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Some tires flex exactly right at a specific tire pressure and road speed to go into resonance and shake the entire truck. It probably is tire brand specific, but test drive it to determine the exact speed at which this vibration starts and the speed at which is goes away. Then increase and/or decrease the tire pressure to see if you have shifted the resonance to a higher or lower speed. I've had passenger cars whose ideal tire pressure sent them into vibration at 55 mph, but it went away at 65mph. Its worth a try. Unfortunately, if I am right, the specific brand is not suitable for the truck's suspension. Yet, the factory/dealer buys them in such quantity that it is unlikely they will quickly determine an alternative tire brand.
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post #37 of 119 (permalink) Old 09-26-2019, 08:46 PM
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Some tires flex exactly right at a specific tire pressure and road speed to go into resonance and shake the entire truck. It probably is tire brand specific, but test drive it to determine the exact speed at which this vibration starts and the speed at which is goes away. Then increase and/or decrease the tire pressure to see if you have shifted the resonance to a higher or lower speed. I've had passenger cars whose ideal tire pressure sent them into vibration at 55 mph, but it went away at 65mph. Its worth a try. Unfortunately, if I am right, the specific brand is not suitable for the truck's suspension. Yet, the factory/dealer buys them in such quantity that it is unlikely they will quickly determine an alternative tire brand.
Each vehicle has a vehicle speed range where it can be more sensitive to a first order tire uniformity. Ideally, the peak is outside the normal driving speed window.
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post #38 of 119 (permalink) Old 09-26-2019, 09:08 PM
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So riddle me this.....

I'd imagine the reason you don't see it on the base trucks is because they don't have 20" wheels with the same tires. We have not witnessed this on any trucks that don't have the 20" Goodyear Trail Runner tires.

If this issue is on all NV8 (electric assist) trucks then why do none of the trucks with 18" wheels have a problem? I ASSume the steering calibration is the same in both trucks (2020 HD LTZ 4x4 with 18" wheels and 2020 HD LTZ/HC 4x4 with 20" wheels) because the steering gear is the same for 2500/3500 HD crew cab with NV8.

Also if you have a LTZ that came with 18" wheels and no shake, but then you swap wheels/tires from a 20" wheel truck with a shake, why does the original truck shake and the truck that you put the 18" wheels/tires on stop shaking?

Lastly, if the calibration is the fix then why are several people reporting that switching to a different brand of tire immediately fixes the vibration without getting the cal updated?

I understand the steering calibration might help some, but the tires are still crap. A couple of these trucks showed up with over 60 pounds of road force that increased as miles were put on the trucks.

GM should've never went back to Goodyear tires and they should still give people the option to upgrade to Michelin tires when ordering the truck, just like in previous years.

The slight shake of just the steering wheel isn't a huge concern of mine now that we got the ridiculous amount of vibration out of it. Now you can see it on the steering wheel, but you can't feel it. However when my truck (and the other 3 LTZ and High Country's) trucks first came in, the vibration shook the entire truck.

The other interesting thing is that lowering the tire pressure actually makes the shake worse. It's totally opposite of everything the field engineer, brand quality and us thought, but it's true. The PICO levels we obtained on my truck were actually worse when I went from 80 PSI to 65 PSI and they got even worse with a few hundred miles on the new tires. We had road force readings on the 2 tires we replaced go from under 20 pounds when we first mounted them to over 60 pounds in ~600 miles of driving the truck. One of them also developed a "thump" noise when spun up on the road force balancer. The thump noise corresponded perfectly to the area of the tire that had an excessive amount of the internal ribs molded into the tire. Even worse is that one of the tires was on the rear and the steering cal won't do a damn thing for a vibration from a rear tire.

I'm not trying to argue, but we've been dealing with this for several weeks and ~30 hours worth of labor so what we've seen (and documented) is slightly different than what engineering, TAC and the "subject matter experts" have been saying.[/QUOTE]

The 20" tire is standard on the custom trucks and available as an option on LT. They are building a rich mix to start the program with mostly at4, denali, ltz, and HC. These combinations all have uplevel steering gear and mostly 20" tire.

If you are getting high pico data, then obviously you have a first order tire issue that needs to be addressed. Unfortunately they have a ton of trucks sitting at flint for extended periods that I believe is leading to some tire damage.

I will stand behind the Goodyear tire. I firmly believe it is the best tire performance wise you can get on these trucks. It's the best riding, trailering, handling, and fuel economy tire. It's also very good for snow, wet, and noise. I will eat crow if it's bad for warranty.

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post #39 of 119 (permalink) Old 09-27-2019, 11:10 AM
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I don't have any information on other wheel sizes, however I have driven multiple Super Duty trucks over the last 10 years. These new 2020 GM trucks have the same size tires as the Super Duty trucks. And as you know those super duty trucks generally come stock with the Michelin LTX AT2 tires. This wasn't rocket science on my part, I knew what tire sizes were available and I knew the Michelin tires had more than enough load rating. That being said, I'd have to disagree with the Goodyear tires having the best performance, best riding, trailering, handling, fuel economy, snow, wet, and noise. Personally there are a few Hankook, Firestone, Bridgestone, and Cooper tires I would put above Goodyear.

Regardless of what tires we all have the freedom to use, my own research has shown that the Goodyear Trailrunners have not performed well on multiple other car manufacturers. The fact of the matter is, I spent money after buying a new truck to replace tires that had vibration problems. Could I have had my local tire shop road force balance etc.? Sure, but researching the tire itself lead me to believe that it was going to be a pain to deal with. Does this mean I want everyone to abandon their Goodyear tires? No. Does this mean every Goodyear tire is going to have issues? No. But the old saying is, if it looks, sounds, and acts like a duck.... its probably a duck.

2020 GMC Denali HD 3500 SRW Quicksilver

- Michelin LTX AT2s
- BAK Revolver X4
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post #40 of 119 (permalink) Old 09-27-2019, 12:07 PM
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But the old saying is, if it looks, sounds, and acts like a duck.... its probably a duck.
Unless it's a merganser, which looks and acts like any duck but has a pointed bill. It quacks like a duck with a cold though.

https://en.wikipedia.org/wiki/Common_merganser

There is no such thing as universal anything. No mater how good something is at a particular use or how happy someone else is with it, there is some use or someone else who will not like it.

It appears that Goodyear has come up with a lemon. That is all there is to it. I'm sure their ideas seemed good at the time and that the guys building the tires are doing their usual quality of work. It just turns out that there is a combination of circumstances that happens on late model GM trucks that doesn't agree with them.

I believe the reason GM is saying that they will come up with a calibration is because once a calibration is found that stops the truck from doing the ChaCha going down the street it will be cheap to implement. Changing all of those tires would be expensive.

I was working at Ford then Explorers were having blowouts right and left. Lots of those supposedly deadly tires wound up on mechanic's trucks. Just keep air in them and they were just fine. If it should happen that GM decides to replace these Goodyears you can bet that many of them will fall onto mechanics trucks as well. What is fit for the goose isn't always what is fit for the gander.
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