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Could you guys explain the speeds you are traveling and is it a noise or feel in steering wheel?

If you start your truck and quickly turn the wheel back and forth quickly on asphalt and don't here a clunking sound, then your upper ishaft is probably fine.

If the noises are at slow speeds, then it could hydraulic noises.

#iworkforGM
I could feel a clunk/ rattle in my steering wheel. It feels like it’s transferring from somewhere towards the bottom of column. It’s felt at all speeds and more when on a bumpy surface or if I turn and hit a bump you can really hear and feel it pretty good. After 5 different upper steering shafts and no change I really don’t think it’s the steering shaft. If you have any ideas on what else I could check please let me know.
 

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From both of your experiences, I can't definitely tell what is from your description. The problem with these 2020+ trucks is they went to integrated front sheet medal (fender structure connected to cab in one piece without adding any isolation to the steering system. The whole body is isolated from the frame except the steering system which is hard mounted to frame and comes into the cabin. Every steering now travels up the steering shaft and the steering acts as the microphone. With all the design issues with upper ishaft, everyone assumes that is the issue.

These trucks due get alot of road feedback through the steering wheel especially on corners. There really is not a fix for that. You need an isolated ishaft to calm that done. Isolated ishaft is not planned.

There are some hydraulic rattles that can be hear. They generally get worse when it gets cold. You usually can hear and feel them under 25 mph. There are hydraulic pulses that are road induced that cause the steering cooler to rattle. GM does not have a solution to fix. I have made trucks better (reduce amplitude) by loosening the cooler and recenter bolts in bushing. I have removed the steel bushing in rubber isolator. Also, if you remove the left front wheel liner, you will see the steering gear. Sometimes, the input and output lines are touching. Loosen the jam nuts and rotate away from each other. If you add about 2ft of rubber line to the return line before the cooler the rattle will go away.

I get a clicking sound when I start up the truck from cold. It only happens once or twice then you can't repeat until cold again. I'm not sure what that is.

#iworkforGM
 

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Every steering noise now travels up the steering shaft and the steering wheel acts as the microphone.

#iworkforGM
[/QUOTE]

Fixed my missing words.
 

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It would be good to know if you guys with higher trim trucks (slt, at4, denali, ltz, hc), put the truck in tow/haul on rough roads and see if there is any difference. The steering cal changes to add more damping which increases the efforts.

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2021 Denali HD
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It would be good to know if you guys with higher trim trucks (slt, at4, denali, ltz, hc), put the truck in tow/haul on rough roads and see if there is any difference. The steering cal changes to add more damping which increases the efforts.

#iworkforGM
I’ll try out the tow haul and report back. Please let us know new part # when available for shaft. Thanks for the intel!
 

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2020 GMC Sierra 3500 HD Denali
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I get a clicking sound when I start up the truck from cold. It only happens once or twice then you can't repeat until cold again. I'm not sure what that is.
I get that same clicking. I think it is the little plastic bushing/bearing in the boot at the firewall. i was going to take mine off and grease it, but have yet to do so
 

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It would be good to know if you guys with higher trim trucks (slt, at4, denali, ltz, hc), put the truck in tow/haul on rough roads and see if there is any difference. The steering cal changes to add more damping which increases the efforts.

#iworkforGM
I have a 2021 Denali and just made a trip with my trailer and I can say there is no difference.
 

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I have a 2021 High country Duramax with the SAME issues and its driving me nuts, i took apart the I shaft (old revision) and greased the hell out of it...no change, added cognitio idler and pitman support, no change. took out wheel liner and ziptied the firewall boot, no change, low speed thumps over bumps felt thru steering wheel. seems like suspension but felt thru wheel. In for updates and findings, will try anything lol.
 

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I have a 2021 High country Duramax with the SAME issues and its driving me nuts, i took apart the I shaft (old revision) and greased the hell out of it...no change, added cognitio idler and pitman support, no change. took out wheel liner and ziptied the firewall boot, no change, low speed thumps over bumps felt thru steering wheel. seems like suspension but felt thru wheel. In for updates and findings, will try anything lol.
Im in the same boat. It’s driving me nuts. If I have any luck I will definitely keep you posted. Please do the same.
 

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Im in the same boat. It’s driving me nuts. If I have any luck I will definitely keep you posted. Please do the same.
Was able to do some more troubleshooting, disconnected sway bar links same deal. Checked body mounts, front diff mounts shock mounts all tight. I DID find when I apply load to the bottom of the pitman arm nut I cam move the shaft into the steering box and make a similar "knock". Not sure how much play if any play is allowable. I turned in the adjusting nut a 1/4 turn and belive my situation may be worse. A steering box issue on a 2021??
FWIW I tried tow haul mode and engaged 4 wheel drive during the process and no change.
 

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Was able to do some more troubleshooting, disconnected sway bar links same deal. Checked body mounts, front diff mounts shock mounts all tight. I DID find when I apply load to the bottom of the pitman arm nut I cam move the shaft into the steering box and make a similar "knock". Not sure how much play if any play is allowable. I turned in the adjusting nut a 1/4 turn and belive my situation may be worse. A steering box issue on a 2021??
FWIW I tried tow haul mode and engaged 4 wheel drive during the process and no change.
If you tighten the adjuster too far, the steering wheel will not return to center. A little goes a long way. My gut feeling is your issue is hydraulic.
 

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Was able to do some more troubleshooting, disconnected sway bar links same deal. Checked body mounts, front diff mounts shock mounts all tight. I DID find when I apply load to the bottom of the pitman arm nut I cam move the shaft into the steering box and make a similar "knock". Not sure how much play if any play is allowable. I turned in the adjusting nut a 1/4 turn and belive my situation may be worse. A steering box issue on a 2021??
FWIW I tried tow haul mode and engaged 4 wheel drive during the process and no change.
I’m able to make the similar clunk when taking a pry bar under the pitman arm nut and pressing on it. There is play in it as it travels up a bit and produces a clunk sound. At this point the steering box and column are the only things that have not been replaced.
 

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If you tighten the adjuster too far, the steering wheel will not return to center. A little goes a long way. My gut feeling is your issue is hydraulic.
I ended up returning the adjuster to normal position. Returns to Center fine. I do agree it seems hydraulic. At high way speed taking a slight turn I feel a hydraulic hammer effect very slight. I wanna believe its the shaft but I greased the he'll outta it and didn't do anything different. Anyone wanna donate the newest revision shaft so I can try it? Lol. The new PN posted above hasn't hit the internet yet from what searches i did.
 

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I ended up returning the adjuster to normal position. Returns to Center fine. I do agree it seems hydraulic. At high way speed taking a slight turn I feel a hydraulic hammer effect very slight. I wanna believe its the shaft but I greased the he'll outta it and didn't do anything different. Anyone wanna donate the newest revision shaft so I can try it? Lol. The new PN posted above hasn't hit the internet yet from what searches i did.
Ended up being the front shocks...i removed them, drove around and the clunk is gone....
 

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Latest upper ishaft part number is 85126059.

#iworkforGM
Hello,
I have the newest version of the ISS. My question is, there is a rubber O ring that just sits on the shaft. Is that suppose to slide between the cylinders or just sit on the shaft.
 
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