Slight forward & backwards seat movement in 2018 Yukon Denali

[8cyloffury]

I recently purchased a used 2018 Yukon Denali (4x4) w/ 43k miles. I have noticed a sound/sensation combination since shortly after taking possession of it. It is a slight "clunk" that reverberates through the seat and I both hear and feel it. 

 

It FEELS like my seat track is moving 1/32" or 1/64" forwards or backwards each time I come to a stop or accelerate. It does not appear to be a lateral (side to side movement) as I do not notice it in turns. 

 

I took it into the dealer and they installed some type of retaining clip that appears to be attached to the underside of the seat. I believe this is the GM version of the "hose-clamp" fix but it has not alleviated the problem at all. (And as I said, I did not notice any lateral movement before or after this was done ). 

 

I was able to minimize the sensation by immobilizing one of the seat motors (which had some play in it) using a zip tie. The sensation of movement (or clunking) on the right side of the seat (closest to the center console)has gone away but the left side click/clunk seems to remain. I cannot find any lost parts or components under the seat though if I grab the seat as a whole and try to move it forwards and backwards on its track there is SLIGHT play and a similar sound (though it's quieter). 

 

I tried to do the same thing with the passenger seat (also powered and heated/ventilated) but it has no play/slop/movement at all and I have sat in it while driving and have not felt it at all. 

 

I have addressed the issue with the dealer but they seem to just be guessing at this point and although I have an extended warranty (the vehicle has 43k miles on it) it is a pain to use and it causes me to be without a vehicle for a day at a time usually. 

 

I have searched and searched online  and cannot seem to find mention of this specific issue except on the previous generation Tahoe/Yukons and those instances seem to involve much greater amounts of seat movement (1/4"-1/2"). 

 

Does anyone have a suggestion as to how to fix this issue? Perhaps a shim or a retention screw tightening, or any bulletin or other known issue that could help me ID exactly what's going on? (I've driven other similar vehicles of similar age and have never noticed this problem before and if I don't have to live with it I'd rather not especially while I have SOME kind of warranty in place). 

 

Any help would be much appreciated. 

Thank you in advance. 

 

 

 

[cs15dah]

I’m still new here but it seems like you’ve missed several recent threads that discuss this exact issue? I think I saw a few of them even have pictures of fixes and the TSB which discusses the problem and the GM solution to it (which it appears you’ve already gotten done, so THAT didn’t work...) The other posts talk about adding washers and even shoe where to place them. When I get some free time, I’d like to do this myself. Mine makes a slight click every now and then. 

[8cyloffury]

Really? The only threads I've found so far deal with the lateral movement or forward/backward play in the prior model (pre-2015) which doesn't seem to translate to this model. 

 

And the TSB also seems to be for lateral movement only. 

 

That said I appreciate you taking the time to comment. Every little bit of data helps me get closer to the solution. 

 

[Havasubum]

There is a TSB on the seat problems.

[8cyloffury]

When you say that there is a TSB on this do you know whether it applies to lateral movement or my issue (forward and backward movement)? I ask bc the dealership already installed a retention clip per the only TSB that they said they had on the issue and it did not remedy the problem.

[The Zip]

7 hours ago, 8cyloffury said:

Does anyone have a suggestion as to how to fix this issue?

My seat moved forward when I pressed the brake pedal, the bottom seat bracket was replaced and it never happened again.  This was 6 yrs ago.

[8cyloffury]

Very interesting. Do you recall if there was a TSB that promted that fix? Also, do you recall what the approximate cost of the job was? 

[The Zip]

TSBs wasn't out yet when I bought my truck.  The repair was covered under warranty.  When I get some time I'll look back a few years to see if I can find the repair invoice. 

[8cyloffury]

I see. Thanks for the info!

[8cyloffury]

Does anyone know if some type of shim for these vehicles? 

Perhaps made of Delrin? 

I know there had talk of using a washer for this purpose but I'm unclear of where it would be placed or how it would otherwise solve the issue. 

[8cyloffury]

Update: 

I took the vehicle back to the dealer and they said that they'd " tightened things up" and that they thought they'd fixed the issue. I drove it off the dealer lot and at first it seemed that the problem had indeed been resolved. However after driving it a few more miles the problem crept back. It would not happen every time I came to a stop and only appeared to happen after making a turn onto an uneven surface or during a turn. However, it then got to the point where the movement seems to be isolated to the left side of the seat towards the rear. Also it movement has been happening only intermittently (meaning not at every slowdown or stop). 

 

I spent an hour or so just looking  under the seat and I noticed that the silver in color bracket that appears to be attached to the seat-elevation motor seems to be flexing and possibly binding which I thought may have been the root cause but I am not certain. There was some play in the screw-gear but it seems to oddly come and go as well. Ie. I was able to move (wiggle up and down) the screw gear with my finger but haven't been able to since. 

 

Again the sensation feels almost like a can of soda or a tin of beans impacting the seat as I brake. I can feel it and it is delayed meaning that I don't feel the sensation until midway through my braking. 

 

I have since attempted the fix of placing a hose clamp on the under side portion of the seat where the white plastic bracket meats the black cylindrical support bar but it appears to have had no effect on the problem whatsoever. 

 

I'm considering purchasing a lower seat assembly off of eBay to see if that replacement will solve this but it is an expensive option and I'd like to exhaust all other remedies first (plus I'm not certain of the legitimacy of the eBay sourced parts). 

 

Anyone have any more ideas or suggestions?