Roberto Bacchus

Greetings.

My 1997 993 has been having issues with both the passenger and driver side seats for quite some time now.

The shop suggested that I replace the seat rails but I was wondering if there are any other alternatives.

Basically both seats jerks forwards/backwards when ever I decelerate/accelerate.

Thanks in advance

kjr914

First & foremost: Fix this before driving the car any more. IF its broken, you don't want to find out when it fails and causes bigger problems...

Manual or power seats? How many way power seats?

With the car parked, brake on, can you wiggle/move the seat bottom at all by hand? You might have to sit in the seat to replicate the problem... There are 6 (or is that 4?) bolts holding the rails down, all 6mm allen heads IIRC....check they are tight. Is there any debris in the seat rails and can you see the metal parts mesh that should be holding the seat into the notches on the rails (not 100% sure, but I think you can see this with a flashlight). Is it only one side of the seat that is moving or both?

If you have power seats, possibly a motor died or a drive cable is broken allowing it to move...

If you can't find any thing obvious, I would start with removing the seats from the car (4 bolts and some electrical connectors and out. Replace the bolts with some new M8 hex head bolts as factory bolts are soft and strip easily) Then, do a thorough cleaning/de-greasing of the seat rails to look for debris and proper operation. You'll be amazed at what you find under the seats...on top of the 42 cents you'll surely locate. Re lube, re-install, re-check the seats.

Also, I've never heard of anyone replacing the seat rails, except for race seats and super tall folks looking for headroom. Has your shop looked extensively at this already? IF their first thought is "replace seat rails", you might want to find another shop... If you tell us your general area, we can help point you to a proper shop if that's the case. (sorry if I'm reading into this the wrong way.)

pp000830

The seat rails are very robust and should not need replacement. I would look into other causes such as the locking mechanism being out of adjustment.

I would also do a quick check that the rails for both seats are mounted into the correct set of mounting holes as there are two mounting positions for bolting down the rails. If the rail on one side of a seat is mounted via the most forward holes in the body mounts and the other side is in the rearward set the seats will tend to have problems as the geometry of the seat position locking mechanism will be cocked as in a parallelogram .

A quick check is to put your finger under the passenger rail fronts and see if both rails use the forward most mounting holes in the body mounts or both are set-back to the 2nd mounting hole set. If one rail is in the first hole and one in the second the cross bar that locks both sides together doesn't work properly potentially leaving one rail unlocked and the seat feels like it is sliding back and fourth as the seat frame twists when the car is in use.

Hope this helps, Andy

Ivan J

If you have power seats, and the motion is a small fraction of an inch (just enough to be noticeable, and annoying), the cause may simply be wear in the drive mechanism. At least, that was my experience. Assuming that you are having the same problem.....

Remove the seat and lie it down so that you have access to the stuff underneath. On each side, there are worms that drive the seat fore and aft. These look and function like large screws. The seat connects to the worm drive via gold colored split metal thingys with plastic inserts. These serve as the nuts that are driven as the worm turns. The split metal things tend to spread, leaving a small gap between the plastic insert and metal that surrounds the plastic. The gap allows the seat to move fore and aft as you drive. It's hard to describe; but, the problem will be obvious if you take a look. AFAIK, replacements for the worn pieces are not available.

I used a pair of channelocks to squeeze the split metal brackets tight against the plastic inserts. After a couple of tries, the metal stayed tight against the plastic. Large Vice Grips would probably work better, leave them clamped on for a while. This was two or three months ago, and the problem has not returned. I know it will someday, the metal is going to want to spread back to where it was.

Roberto Bacchus

Thank you all for your reply.

I took down the chairs and it seems similar to what Ivan J describes. It appears that the bushing/spacer deteriorated over time hence the play on the rails. I managed to wrap some soft metal around it but i'm looking for a more permanent solution.

Any suggestions would be greatly appreciated.

pp000830

I suspect the plumbing section at your local home improvement store has a selection of nylon faucet parts that can, with a little McGuyvering, can serve as a replacement for the worn bushing. Another alternative is to see if some spring clips such as E-Clip external rings can be added as spacers to use up the play space.

Foxman

Check with Lart at Lart's performance. He stocks many of these bits for refurbishing seats. https://www.facebook.com/lartsporscheparts/

Ed Hughes

I'd also find a new shop.

Roberto Bacchus

Thanks again.

BTW the shop is the local Porsche dealer

Ed Hughes

That should have been the red flag.

C4WIDEBODY

ROBERTO.

I have a similar problem with my driver's seat. Have you found a fix to this problem other then above?

Ivan J

Parts like this have nothing to do with the problem.

The issue is a plastic block that is INSIDE the gold rectangular piece that is connected with two bolts on one end, and riding on the worm at the other end. When the seat is against the stop (the round white bushing), you will not be able to see what is actually causing the problem. Back off the adjustment away from the stop, then apply a fore & aft force to simulate what happens when you drive. Look INSIDE the gold piece while doing this, and you will see the play between the plastic block and the gold metal piece.

I squeezed the two sides of the gold piece together to eliminate the play. So far, the problem has not returned. I would not try shoving a foreign object inside the gold piece to fill the gap, because it could cause a jam if it ends up moving to the wrong place.

Paolo1

I had this same problem too and I either must have gotten desensitized to it or it self resolved.

dandyw

I have a problem with the right seat, where there's no fore and aft movement. I was planning on moving the brackets to the rear mounting holes, but that mission is aborted because I can't get the seat to move forward. It looks like the binding is caused on the right worm drive, as the left side wants to move but the right is frozen.

My question is, can you rotate the worm screw manually with the seat installed? I need to get the seat forward to remove the rear mounting bolts...

pilotincommand

Does anyone have a good photo with dimensions of the bushing in question? With accurate dimensions, it should be easy enough to create a 3D model for printing.

I replaced the rear bushings on my seat rails with ones I fabricated using the 3D printer at work (see photos), but I left the front bushings alone (and don't want to disassemble the seats again to measure.