Seat adjuster fix-How To
 

You may notice one day that your formerly rock solid seat now shifts back and forth under braking and acceleration. I've had this issue for a while now and finally decided to tackle getting it fixed. Here's how to remedy that problem.

To do the repair you will need the following:
#2 and #3 Phillips screw driver
Impact screwdriver w/#3 Phillips bit
Small hammer
3/8" drive ratchet
4mm Allen socket
small Straight screwdriver
small locking pliers (aka Vise Grips)
(2) 17mm open-end wrench
rags
solvent
all purpose grease
(24) 1/2" i.d. x 3/4" o.d. nylon washer

Remove the seat from the car and place it on a suitable work space on it's back.
Attachment 937847
Here is the bottom of my 1990 8-way w/memory driver side seat. Others are similar. The two fore/aft adjuster screws are visible running down both sides.
Attachment 937848
Here's a close up of the offending parts on one side.
Attachment 937849
Here's the other side. Those yellowed plastic bits are the plastic cases for thrust bearings on the adjuster screws. When these come apart they allow play into the adjuster screw system and the seat starts clunking back and forth when braking or accelerating hard. We will be removing these adjuster screws and the deteriorated plastic so we can install new plastic spacers and eliminate the movement.
Attachment 937850
First, remove the front motor cover by removing the two securing screws. Here's one. The other is on the opposite side of the cover.
Attachment 937851
To remove the retaining clip for the potentiometer-side drive cable rotate the clip toward the bottom of the seat...
Attachment 937852
Attachment 937853
then tilt the right side of the clip toward the left off of the motor housing
Attachment 937854
then remove the clip.
Attachment 937855
Next we need to remove the drive cable housing retainers here
Attachment 937856
and here so we can remove the drive cable.
Attachment 937857
Use a small screwdriver to pry the clips loose from the housing at the adjuster screw
Attachment 937858
and at the manual seat adjuster drive.
Attachment 937859
You can leave the clips on the metal or remove them completely.
Attachment 937860
Grasp the cable housing and withdraw the cable from the manual seat adjustment drive.

Attachment 937861
Leave the drive cable attached to the adjuster screw for now.
Attachment 937862
Now remove the two Phillips head screws that hold the adjuster drive plate to the seat slide rail. You might need to use a hand impact driver to get them started as they appear to have had thread locking compound applied at the factory. Remove both screws using a #3 Phillips.
Attachment 937863
Gently clamp a small pair of locking pliers onto the square drive end of the drive cable.
Attachment 937864
Use the locking pliers as a handle to turn the drive cable and run the adjuster nut down the adjuster screw away from the upper adjuster screw mount. Give your self 2"-3" clearance.
Attachment 937865
Using two 17mm open end wrenches unscrew the retaining nut from the top of the adjuster screw. This nut also seems to have had locking compound applied.
Attachment 937866
As the upper retaining nut unscrews it will start hitting on the socket head screw holding the front height adjuster unit to the seat frame. This is OK as you can continue to turn the lower retaining nut, which will turn the whole adjuster shaft and finish unscrewing the upper retaining nut.
Attachment 937867
Remove the retaining nut
Attachment 937868
Followed by the plastic bits
Attachment 937869
and the upper thrust bearing.
Attachment 937870
Here's the two thrust bearing washers, the bearing cage and balls, and what's left of the plastic housing.
Attachment 937871
Here's the lower end of the adjuster rod. Remove the socket head screw to allow the plastic carrier bushing that locates this end of the adjuster rod to come off.
Attachment 937872
Use a small straight screwdriver to remove the E-clip that holds the lower carrier bushing.
Attachment 937873
Lower the adjuster screw
Attachment 937874
and remove the carrier bushing.
Attachment 937875
Lower the adjuster screw further

Lower the adjuster screw
Attachment 937876
Until the upper end of the adjuster screw is free of the mount
Attachment 937877
You should now have the adjusting screw and nut free from the seat.
Attachment 937878
Remove the lower travel stop bumper
Attachment 937879
and the other thrust bearing
Attachment 937880
screw the adjuster nut and plate off the adjuster screw.
Attachment 937881
Once the adjuster plate/nut is off the screw remove the upper adjuster stop bumper bushing.
Note: Help from Woody and Buzz not required but strongly recommended.
Attachment 937882
The adjuster nut is cushioned in the adjuster bracket by a plastic surround. This plastic is also deteriorated so I opted to replace it with plastic washers as well.
Attachment 937883
The washers I used didn't fit very snug.
Attachment 937884
so I clamped the bracket with the nut and washers in a vise and compressed the clamp enough to snugly hold the washers in place.
Clean the adjuster screw of all old grease and apply fresh grease of your choice.
Attachment 937885
Notice the adjuster stop bumpers are beveled on one side.
The bevel on both bumpers faces toward the back of the seat when installed on the adjuster screw.
Attachment 937886
Slip the upper bumper onto the adjuster screw with the beveled side facing the bottom of the screw.
Attachment 937887
Thread the adjuster bracket back on to the adjuster screw
Attachment 937888
Clean the thrust bearing parts and apply fresh grease of your choice. Notice each washer is grooved to give the balls a "race" to ride in.
Attachment 937889
Here is one thrust bearing assembled. I'm adding one washer to take up the space of the deteriorated plastic. The other side of the bearing assembly has a bit of the original plastic in place as it has a centering ring. This plastic will eventually give out but I'm curious to see how much longer it lasts so I re-used it on this bearing set.
Attachment 937890
Slip the thrust bearing back on the upper end of the adjuster screw.

Attachment 937891
slip the lower adjuster stop bumper bushing on to the bottom of the adjuster screw, making sure the beveled side is facing the bottom end of the screw.
Attachment 937892
Insert the bottom end of the adjuster screw into the mounting bracket far enough to allow the upper end of the adjuster screw the slip up into the upper mounting bracket.
Attachment 937893
Attachment 937894
Slip the lower carrier bushing on to the bottom end of the adjuster screw. The grooved end goes up.
Attachment 937895
and install the E-clip to retain the carrier bushing.
Attachment 937896
Apply the thread locker of your choice to the socket head screw for the rear height adjuster. Install the screw securely.
Attachment 937897
Drop a new nylon washer over the top end of the adjuster screw
Attachment 937898
followed by the other thrust bearing
Attachment 937899
and another nylon washer.
Attachment 937900
Apply the removable thread locking compound of your choice to the upper retaining nut
Attachment 937901
Slip the retaining nut onto the top end of the adjuster screw. Turn the adjuster screw to get the nut started.
As during removal, the nut will jam against the socket head screw for the front height adjuster at first so instead of trying to turn the upper retaining nut we screw the shaft into the nut using the lower retaining nut until the upper retaining nut is far enough on the adjusting screw shaft to clear the obstruction. You need to make sure that as you tighten down the upper retaining nut parts of the upper thrust bearing (nylon washer, bearing "races", cage and balls, and nylon washer) center on to the shoulder of the upper retaining nut.
Attachment 937902
Tighten the upper retaining nut securely.
Attachment 937903
Insert the drive cable, with locking pliers attached, into the end of the adjusting screw
Attachment 937904
Turn the drive cable and adjusting screw to bring the adjuster nut/bracket all the way up against the stop bushing.
Attachment 937905
Apply removable thread locking compound to both Phillips head screws and secure the adjuster bracket to the slider.

Attachment 937906
Remove the locking pliers from the drive cable. Grasp the cable housing and install the motor end of the drive cable to the drive motor. Make sure the cable housing slips into the hole in the metal bracket.
Attachment 937907
Push the drive cable housing retaining clip back in to place to hold the cable housing. Be sure the housing isn't so far through the hole in the bracket so as to interfere with the manual seat drive gears.
Attachment 937908
Install the retaining clip on the adjusting screw end of the drive cable housing and that side is complete.

Repeat the entire process for the other side, making sure to re-install the wire retainer removed at the beginning, and the whole seat should be rock solid again. You may have to turn the drive cables slightly to get their square ends to align with the socket in the drive motor correctly but it won't be enough to affect straight travel or position.

Hope this helps

Mike

Holy smoke! Great write up. What year?

To infinity and beyond! Nice write-up:D. Will come in handy in the near future.

The seat in the pictures is a comfort seat from my 1990 S4.

Mike

Excellent thread! How did I miss this one..

Need help with this.
 

Do you know where I can purchase the Lower Carrier Support Bushing??

Sorry I don't have a source. They were never offered as spares by Porsche. You might be able to get them from Recaro, the original manufacturer of the seat.

Mike

Terry,
we had a few of these 3D printed. PM Mike Frye as he might still have some left.

Cheers,
Myles

Thanks -
 

I'm new to the site. I'll give it a try.

Thanks again.

I need a couple of these - anybody have some lying around?

Awesome write up --

My passenger seat in my 993 (same seats) is locked up and I tried to adjust the seat manually
with a drill on the speedo cable -- just ended up with shredded cable.

I can't find a bit to fit into the end of the adjustment mechanism to be able
to move the seats forward and back to be able to remove the seats.

I know its an S3 bit -- but no where can I find an S3 bit deep enough, and skinny
enough to get past the part where the cable clips in AND engage deep enough
to attempt to turn the mechanism.

So 2 Q's -- where can I find such a bit --

If it does not exist -- is there a way to move the seat fwd/backwards by some other means?

thx,

Mike