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Seat Looseness

44525 Views 107 Replies 37 Participants Last post by  rorz12
I couldn't find the original thread on this subject, so forgive me for starting over. (Maybe it was the other forum.) I finally got around to looking under the seat and this is the letter I wrote to BMW. I'll let you know if and when I here back.

There's a second issue I didn't mention, but I didn't want to muddy the waters. I also found that the thigh support can move a little if it's positioned anywhere other than full in.


I would like to bring to your attention an issue with the 6 Series front seats that seems to be common amongst many owners based on the forums that I read.

Simply put the front seats have a looseness that allows movement under load when the car is cornering. It does not take much lateral input to generate movement.

I have investigated this problem to isolate the cause. I am an engineer with 30 years automotive experience, so please take my analysis seriously and forward it to the appropriate personnel.

There is a cross-car steel support tube that passes through two (I assume urethane) bushings under the forward edge of the seat frame. This assembly is part of the mechanism used to raise and lower the front edge of the seat cushion. The bushings, attached to the seat cushion pan, are oblong in relation to the diameter of the tube to allow longitudinal movement as the mechanism is raised and lowered. Lateral movement is controlled by flared "stop" features on the steel tube on either side of the outside (driver) bushing. It is the relationship between the sides of this bushing and these stop features that is problematic.

If the front seat edge is adjusted to any position other than full stop (high or low), which places the tube firmly against the bushing, lateral movement can occur between the sides of the bushing and the flares on the tube. This motion is easily felt by the seat occupant as the bushing (and seat) bounce back and forth between the two stops on the tube. Hardly acceptable on this class of automobile.

Many 6 Series owners have taken their cars to the dealership with no resolution. A permanent solution needs to be driven from the top down. It seems a simple solution would be a wider, harder lubricious bushing to prevent the unwanted lateral movement without binding the adjustment mechanism. But I will leave that analysis the the BMW engineering staff.

Thank you for your attention to this important matter. I look forward to a solution and positive response.

Feel free to contact me at any time to discuss this further.

Best regards,
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my 2014 640i cv with 16K is going in Monday for second can can sure I'll take a printout of this thread with me. They have replaced left seat track on drivers seat so far. Will advise..what a great site.
Allan Thompson, please post drawing. 640ijims
Dealership replaced "seat pan base/mu" pn. 52-10-7-375-199. Problem solved entirely, am happy camper. Allan, am keeping you bracket fix just in case.
Nirav1478, assuming a gan coupe seat arrangement is same as my 2014 convert, seat pan replacement ( part # above ) should be fix. Dealer tried seat rails; both sides; minor bit of relief that went away quickly. Pan is the deal.
6 series seat rracks

Seatt pan in my post, no idea of tsb
I'm in for second fix on this issues. If it goes like last time..replace right seat rail, replace left seat rail and finally replace pan...the last one will fix it.

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Replaced seat pan again yesterday, seat solid again.

I believe problem is letting seat back "fall" back into position after releasing and putting forward for rear seat access...dunno..just sayin'
Part numbers for seat movement problem

Replaced seat pan again yesterday, seat solid again.

I believe problem is letting seat back "fall" back into position after releasing and putting forward for rear seat access...dunno..just sayin'
Thought I'd post p/n's for those affected last week (3/1/17)
Part numbers replaced:
52-10-7-314-275 mounting how're
52-10-7-375-199 seat pan

I still believe that allowing seat back to fall into position after moving it forward for rear seat access is either the or a contributing culprit!:eek:
Sorry to report the "fix" did NOT work slight side to side rocking started yesterday. Will advise as I work the problem.

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Well, entire seat frame on order, theoretically problem will be solved.

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Pick car up today, see if whole frame as Walter White suggests solves problem.

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WW, I think you have it. Entire seat frame replaced , God is back in heaven....& I'm looking. For reason to go for a ride. Replaced high speed fuel pump on same visit...performance restored? 640ijims

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Two days and all is well. High speed fuel pump replacement cured a slow performance degradation

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One month into mission, seat is still firm.

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My cushion appears to be better, but then it was molded by my bottom for 24k of its 25 k life. Received a Dinantronics Sport today, may install next week
My local store here in Sarasota eplaced seat pan 2x , various rails 2x, finally replaced entire seatframe ..problem fixed. As BMW sells under 30k of these world wide, it is not surprising they do not put a engineering team on this for 10-15 vehicles.
Seat looseness f12/13

I'm about 3 months into mission all is great
Nearly 11 months in and all fine on new frame. I believe cause was letting seat fall into place moving it to access rear sear

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The only way ,IMHO , to fix shifting front driver or ( passenger seat), is to replace the entire frame. I had multiple pans, seat rails, supports, bushings, you name it...only thing that repaired problem is full frame. I’m 19 months into this repair and all is well. I do NOT allow drivers seat back to fall back into position after tipping seat forward any longer, as you may surmise.

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Occam’s Razor

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1 - 20 of 108 Posts