borland

I found a nice matching pair of supple leather seats in Silk Grey, so my project plan for this pair of seats, is to make a ‘like new’ driver seat, by swapping passenger and driver side’s leather. If I’m lucky, I will be able to swap the completed driver’s seat with the one installed in my 90’ S4.

These seats were advertised as ‘from a low mileage 89’. They are the common 8-way seats, so they don’t have the lumbar adjustments or seat heating elements. The driver’s bolster has some typical wear, but the passenger seat looks almost new.

This project presents some challenges, as a few problems:

- Seat wiring is significantly different between driver and passenger side. Driver side seat has seat position memory circuitry while the passenger seat lack it. Even the seat backrests have different wiring harnesses and the passenger side lacks the backrest potentiometer required for driver side seat memory).

Here's the driver side seat...



and the much simpler wiring on the passenger side seat....



I started with the leather backrest swap, so what follows, is how I removed the backrest from the seat bottom for the driver's side.

First thing is to disconnect the backrest harness from the seat wiring. There are some connectors to disconnect and some nylon stay ties to cut. But the harness is looped under some seat bottom leather that needs to be undone by cutting a few hog rings (red arrows show were removed in photo below).



There are several hog rings that need to be cut off to allow for the disassembly. I purchased a small bolt cutter at HFT. You could might be able to use a pair of diagonal cutters, but the bolt cutters make it much easier. For the leather reassembly, I purchased hog ring pliers and hog rings from eBay (more on those later).



Now with those rings removed, you can see how to remove the backrest harness from the base. But under that leather flap, there’s another hog ring to remove and a wire strap to unwrap just below.



You can now see the harness free and the leather undone with the strap wire hanging down.


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With the wiring harness free, its just a matter of removing hardware from the side mounts to allow removing the backrest from the seat bottom. As you can see in the photo below, just two bolts on each side and a cable to unhook. But, because the backrest motor is located inside the headrest, there’s also at drive shaft or pin that allows this motor to drive the gears that adjust the position of the backrest on both sides.

You’ll also see white factory alignment paint. If your swapping just the backs and rewiring the backrest motors, it would be a good idea to run the backrest motor to the factory alignment position. I used a fresh 9V battery to do this alignment by applying electrical power to the harness (yellow and green/yellow stripe wires).



To remove the drive shaft or pin, with a 2.5mm hex tool (Allen wrench), remove the small screw (arrow in photo).



You’ll need to find another longer screw with the same threads to use as a tool to extract the drive shaft or pin. The photo below shows the drive shaft or pin partially removed using the longer screw as an extractor tool. There’s also a rubber washer that will pull out with the drive shaft or pin. Same case for both sides of the backrest.


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Remove the drive shaft or pin on both sides of the backrest. Loosen the four bolts and unhook the cables. Not shown in the photo (hidden by the leather, just below the upper bolt) are cable guides that the cable need to released before removing the bolts and backrest.



Here’s photo showing the seat ready for removing the side bolts and pulling off the backrest.



And with the backrest removed, you can see the hex slot where the drive shaft or pin fits in.



Here’s a photo of the hardware that was removed.



And the backrest separated from the seat bottom.

borland

Backrest Disassembly...

Now for the next major step…. removing the leather from the backrests.
I first removed the backrest leather from the headrest and side bolster leather.
Start at the bottom of the backrest. With a pair of needle nose pliers, straighten the tabs to allow pulling free the bottom flap of the backside. Then working from one side, release the leather from the tabs, one at a time.



After releasing the backside leather flap from all the tabs, fold back the leather to uncover another flap (for the front backrest leather). You’ll see a couple hog rings that need to be cut off.



Flip over the backrest to work on the front side now. The backrest leather is held in place by a few hog rings between the leather and the horizontal wires of the backrest frame. Clip these off, and work your way from the bottom toward the top on both sides.



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Here’s a photo showing the backrest leather with all of the bottom hog rings removed. Only thing holding it on now are two hog rings at the top. Clip these hog rings off from the top front.



This photo show marks with red arrows, the location of the two top hog rings.



And with the backrest leather removed.



This is as far as I got. So, more later…. Next update will be the backrest bolster leather removal.

Herman K

Ask me how I know..

This thread illustrates.

All the work I had to do all this after my leather supplier guaranteed me that everything he supplied me would fit my 1994 it worked out that he gave a set of seats with the bases of a 1984 model.

I my case an expensive lesson learned.. before you get into any seat rework make sure you have the same year model base to work with!!

Net result is that I got some extra seat bases laying around that I'm going to sell for parts

finally!

Why not just swap the seats themselves out borland instead of going ot all that trouble?

heinrich

Ridiculously heavy suckers, those seat bottoms eh Barry.

borland

'Lots of work' .... yes, not easy, not for everyone.

'Why not just swap the seats themselves' ..... The wiring harness and controls are L/R, so that won't work.

'Ridiculously heavy suckers' Yes, they are. I think Rob showed us they weigh about 62 lbs.

borland

To remove the backrest release *****/levers, I used a length of cord looped around the backside, then pulled the **** free. On the pull side of the cord, I wrapped the end around a stick to act as a handle and made the job easier on the hands. There's a metal clip between the lever and the **** which helps keep the **** from working free, and also makes removing it a little harder.



Here's a shot of plastic pieces and clip...



After that, its just a matter of removing the leather from the frame. Start at the bottom and release the bottom leather from the bent up frame clips. On these bottom leather flaps, there are some hog rings to cut ...



again...another hog ring to cut..



and finally the bottom leather is free ...



I then cut the hog rings on the front, being careful not to cut the springs. There are four springs on each side. The springs are painted white, but they look similar to hog rings, so be careful.

Here's showing the the leather free from any hog rings...



To completely remove the leather, you'll need to reach inside and free the leather from the frame and foam, as the leather has been on for so long, it's not going to just slip off. So after you find and release the stuck leather parts, nothing glued, then it should just lift off.



Everything you see here (foam & padding) is glued to the frame. Here's the backside of the backrest. Notice the springs I mentioned.



And again with the thin foam piece back in place. It came free with removing some of the hog rings.


This thin paper backed foam piece fit as shown behind the lower back flap.



And again with the foam aside, you can see the impression of the foam in the leather..



That's it, backrest leather is removed on the driver side seat. Next is doing the same for the passenger side backrest.

Next update to this thread, I'll be doing the driver/passenger leather swap and reinstallation.

borland

Here’s the final update..

Reassembly Tools/Supplies used:

- Hog Ring Pliers: I purchased a used pair of 45 degree angle nose hog ring pliers on eBay for about $25 delivered. They are Republic, model XXL




- Hog Rings: I also purchased a 125 count bag of plated (anti-rust) car upholstery hog rings, ¾” crown,14 gauge, also on eBay for $5.50 delivered.



Here’s a couple photos showing the reassembled driver and passenger backrests.

First the new Driver side replacement backrest...



and the new replacement Passenger side replacement backrest...



Sorry no detailed assembly photos, as the assembly is pretty straight forward. Just do everything in reverse order of disassembly, matching hog ring locations that the factory used. Here’s some assembly notes:

- Start by inspecting the leather cover. The side bolsters have a polyester fiber backing sewn into the cover. I found this backing to be matted on the driver’s bolster, so that needed to be smoothed out to eliminate any bulging of the leather one back in place on the seat. That turned out to be easy, just needed to pull on the fibers with my fingers to loosen them up.
- Placing the cover back over the seat foam. It will take some massaging of the leather to work it back in place. Once the fit is correctly, secure the bottom leather flaps in place using hog rings. Then start as the front top and work your way around the bolster, refastening the hog rings. The center leather piece first clamps at the top with two hog rings, clamped with the pliers from the front (these two rings need to be tight in order to eliminate any gap where it meets with the headrest).
- With all the hog rings, use your fingers to make sure the ring grabs the wire sewn into the leather cover before squeezing the pliers. Take your time with the hog rings. I clamped a few that I didn’t like. It is easy to cut them out with the bolt cutters and replace it with another. No harm done.
- The hardest part is securing the backside bottom flap to the frame hooks. I used a hook fashioned from short length of bailing wire and a pair of vice grips. I used the hook to stretch the leather flap enough to fit it over the frame hooks, one at a time. A pair of long nose pliers and a tack hammer was use to bend the frame hooks back in place.

borland

Seat bottoms Leather Swap -

I also swapped the bottom leathers between the driver and passenger seats. This was significantly more involved, in that it required hand stitching the seat bottom pieces so as to reutilize the bottom skirt and vinyl piping. If it were not for the 8-way switch cutout holes in the leather, the swap would have been much easier.

Here’s some photos showing the seat bottom strip down and associated seat components.
Red arrows pointing to hog rings which need to be cut off.





After removing the hog rings from the bottom of the cushion, you simple bend up the bent over tabs (yellow arrows) along the bottom sides.



You’ll need to remove the 8-way switches and harness by snaking the wires through the frame (not real easy).



The leather cover comes free after separating the glued down leather from the cushion enough to cut off additional hog rings near the top. With the leather removed, here’s the driver’s side foam cushion.



Here you can see where the hog rings grip metal rods (red arrows ) embedded in the foam cushion.



Here’s the underside of the leather seat bottom piece



And the driver’s seat bottom frame.



For the hand stitching, I used a sewing machine needle to reattach the pieces with a machine stitch. Thread I used was a color matching commercial nylon upholstery thread ( #69 bonded nylon thread). I purchased this inexpensive thread on eBay.

After hand sewing the swapped seat bottom leathers….. here I’ve used masking tape to mask off for the adhesive spray (3M Foamfast 74).



Similar masking for the foam bottom cushion……



In order to keep the two from sticking together while fastening the hog rings, I used waxed paper between the two pieces.



The rest is just restoring the hog rings and metal tabs, reinstalling the seat switches, rails, motor assemblies, cables, and wiring harness.

Here’s the finished Passenger seat next to the Driver’s seat which I removed from my 90’ S4. The project called for these seats (the pair) to be resold (already sold).

Both seats shown here have driver seat leathers. I’ve touched up the driver’s seat bolster wear with matching leather dye. Not shown, is the installed driver seat with passenger seat leather.



Another couple views..

Gary Knox

Barry,

WONDERFUL write up. I did this exact same thing to a set of "spare" seats I bought last fall. Driver's side had lumbar, and I want to re-upholster them and include heaters for the seats. May take a while to get the $$$'s together, as I want to do them in the supple leather style.

I used a previous write up from Rennlist on how to remove the seat back, but wish I'd had yours for all the other details. I'll certainly keep it for the re-upholstery and reassembly process when I'm ready to do that.

Again - my compliments for a great writeup.

Gary Knox

Rob Edwards

Truly outstanding writeup, Barry! Nicely done!

928Myles

Borland,
will you have any redundant pieces from this exercise? Specifically I am after one of the brown plastic bushes the end of the adjustment rods sit in. The part is clearly visible in picture 3 of post 1. IIRC it is held in by a circlip.

Thanks,
Myles

Herman K

Those are like large plastic/nylon washers in the USA you can find substitutes at most hardware stores like Lowes or Home Depot you may have to modify the hole to fit the adjustment rod.

928Myles

Herman,
the one I am missing is about 20mm long and 20mm in diameter (outer bit be circlip) and a sort of keyhole shape where it fits into the seat frame. Would need some significant modifications to a very thick washer to make it work:-(.

I tried a few years ago to source a replacement with no luck.

Myles

borland

Myles,

Sorry, I actually reused all the parts, only transferring my '90 seat rails to the '89 driver seat bottom since the driver seat belt latch differs from the '89.

As you can see from the Porsche Seats parts catalog (STZ_USA_KATALOG.pdf) which lists many parts, that the bushing is only sold as part of a left or right seat rail. A machine shop could easily make the part from a piece of teflon, provided you have one they can use as a template.



You can download the Seats parts catalog here...

http://www.porsche.com/usa/accessori...artscatalogue/