GlenL

I'm working through installing some 996 seats into my 944. There are an assortment of posts on doing this but they don't seem to cover the whole problem. The seats I'm installing are from a 2002 996 and have power and heat with memory on the driver's seat.

Some procedures cover manual seats or adding heat. I'm not going to cover it all, either, but will describe how I'm mounting the seats into the car.

Below you'll see the adaptors needed to securely mount the 996 seats. There may be minor variations but I believe Boxster and 997 seats are the same. Some threads have discussed moving the seats to 944 rails and that solves a problem but leaves 6-ways of adjustment behind. Other guys have described mounting them but it seems they're just using the front holes. I don't think that's acceptable for safety and especially as this car is run on the track, too. It's gotta be solid. Also, mating up the front holes means the long bottom rails stick out into the rear seat foot area. Humans may need to be under 5' to sit there and having the rails further forward helps.

So...

A good thing about the seats is that the tracks are both 40cm apart. No adjustments needed there. A problem is the the power seats have the gear rack mounted in the bottom channel on both sides. The track is longer than the spacing between the holes on the 944 for mounting. What to do?

I spent a good deal of time looking it over and trying to figure out a strategy. I was tempted to just drill through the body and run bolts through to big washers under the floor pan but that seemed shoddy, would likely be weak, crush in a bit and, of course, rust.

What I came up with are the four plates pictured below. Those are roughly halves of two bars from Menards and were 1/4" by 1 1/2" by 30". Those were cut into two pieces each 44cm long.

The mounting of the stock seats uses three bolts on each rail. Two are in the rear and one is in the front. The front and middle bolts are in the same place with the rear-most bolts being offset a bit. The bolts are spaced by 30cm and 2.25cm on the outer rails and by 30cm and 4.5cm on the inner rails. Those holes all have threaded plates inside them that take M8 bolts with 1.25mm threads. There's a pic of the body holes for the outer rail below to illustrate. Apparently, they felt a need to prevent the seats from being swapped side-to-side so made the spacings different.

That spacing is a problem as the three 996 seat mount points are spaced 37cm and 2.5cm apart. The inner and outer rails are the same. A problem is that the gear rack is like 33cm long so no way to just bolt through the channel to more front and rear stock mounting points. Also, one of the 996 mount points is a stud or spur that sticks into a hole and is riveted into the channel.

The answer I came up with was to make an adaptor plate. The trick is to use some beveled head bolts to mount the plates. Other Porsche junk collectors will recognize the bolt in the picture as holding 928 door latches. Maybe they're on other Porsches, too, or you can source something similar. The adaptor plates allow the spurs on the 996 seats to go into the parallel middle holes. The lower channel rails of the 996 are drilled and filed to allow bolts to go through the rail, through the plate and into the stock rear-most holes.

The forward bolt hole into the body gets the beveled bolt. The plate is drilled and chamferred so the special bolt is flush with the surface and the seat rail sits flush to the adaptor plate.

The bolt hole of the seat rail get pounded flat (it's originally angled) and gets bolted to the fore-most hole in the adaptor. That is attached with a simple bolt, washers and nut.

The four holes are drilled, from front to back, in spacings of 7cm, 30cm and 2.25cm for the outer rails and 7cm, 30cm and 4.5cm for the inner rails. The first, third and fourth holes are done with a 3/8" bit. The second hole is done with an 11/16" to be a bit stronger and then countersunk with a 5/8" bit. The angle of the bit face doesn't really match the bolt head but it works.

The seat rails need some modification, too. The inner rail needs a 3/8" hole drilled 4.5cm back from the spur centerline. The outer rail needs the existing hole filed on the forward edge to make a 2.5cm center-to-center with the spur become a 2.25cm c-to-c spacing. Might not sound like much but it needs to be done.

Some grinding and painting and it's done. Now to finish up the wiring and dye the seats.

GlenL

This has been a long project. Lots of mini-projects strung together.

here's the mounting brackets for the passenger side in the car. The bolts at the rear (left) are in for aligning the adapters. Those get removed and then re-inserted when the seat is in place. Add short 8MM bolts with nuts to secure the front. Worked like a charm.

GlenL

Now here's fun: how to mount the seat heater switches and the driver's memory seat switch.

First off it "where." I chose the ash tray as it's well-located between the seats and I never use it.

Then how to get the switched 12V and ground. The seat heaters need 12V and the memory switch needs switched 12V and ground.

Digging around below the radio I found an un-connected connector that has switched 12V and ground. Not sure what option that's for. Digging through old Porsche harnesses I've got handy, I found two pins that fit the connector.

I released the console a bit and could run the wires below the shifter section. The 12V gets a connector with an outside shroud to avoid shorting.

GlenL

Then the switches need to get mounted.

I took a piece of acrylic plastic and traced the ash tray onto it. Cut with a jigsaw.

The trick is to mount the switches. The heater switches are kind of odd as the switch rockers are bigger than the bodies and the bodies have clips lower down. The approach was to salvage the mounting I had and glue that to the plate.

I got the console section from a Boxster off eBay fairly cheap. It included the seat heater switches and the window switches. The switches look a bit different than 996 switches, being oriented 90* off, but they are electronically identical.

I cut the console section up and then shaped it to be symmetrical and flat. Then cut a hole in the plate to accept the mount. It all took a lot of cutting, shaving and filing to make it work.

GlenL

Then to mount the memory switch. Made that easy by cutting a hole and gluing the switch from the back. It also took a bunch of hand work as the switch has all these triangular braces or somesuch off the nominally rectangular switch section.

The pics shows the wiring for the memory switch. I couldn't find the connectors for that at all and fabbed that harness using hook-up wire with female pins crimped on. As in following posts, I got some connectors with male/female pins to allow separate the wiring harnesses essentially at the floor under the seats. I measured the pins on the switch and memory unit and got pin sets that'd work for them. The female sockets fit tight to the pins.

GlenL

Getting all the wiring right was a challenge. First there's figuring it out from the schematic and then fabbing up the harnesses. I didn't have the crimping tool and mated the wire to the contacts by crimping with small pliers. Then I soldered them and added shrink-wrap. Close to 60 contacts and spade lugs.

I got connectors for seat power from a Boxster. That included wires for the seat heaters although I had to move the contacts around in the connectors. And the power pins weren't in the right places. Still, easier than cutting and splicing everything.

The passenger side didn't have memory so everything runs through the one connector. That gets switched power for the seat and constant power for the power seat section. There's four 22ga (?) wires to the heater logic.

The driver's side was more complicated. The power connector only feeds the seat heater. There are separate connectors for the power and logic for the memory seat. I didn't have those so made them That's shown in the first pic.

The second pic shows re-using the stock 944 power connector to feed to the seats and memory module. Gotta "Y" the power and grounds to multiple places.

One thing I couldn't figure out was how to make the power seat come on when the door is opened. Apparently, on the 996/Boxster, the lights are grounded and power comes ON when the door is opened. On the 944, all the lights are powered and the ground comes ON when a door is opened. So, the power seats only work once the car is turned ON. I was concerned about power drain if I left it enabled all the time.

GlenL

This pic shows the switch plate along with some of the wiring. Note the 5-pin connectors that were used to separate the wiring harness at the floor.

The plate was painted Burgundy. Doesn't exactly match but I got the plastic paint for like a buck at unclaimed freight.

GlenL

Here's a detail of the heater switches. Each wire got a female spade lug contact and everthing is carefully numbered. The contacts needed to be bent almost 90* to fit into the hole for the ash tray. I needed to cut out the carpet below the tray, too.

GlenL

Here are the switches installed. I used some two-part plastic epoxy to assemble it.

GlenL

And the seats are in!

You might notice that these are burgundy and they were gray before. That's the magic of Leatherique dye.

The dying process was a lot of work. I'm fairly happy with the results but some more care would have had a better result.

A challenge in dying seats is that the leather dye is put on very thickly and it's strong. The Leathrique kit comes with "prepping agent" that's supposed to take off the old dye. The suggest doing that with some fine sandpaper. Well, I'd have needed a gallon of the agent and a month. Checking the internets, I found that de-natured alcohol will take off the dye. I used that along with steel wool to do most of the dye removal. You have to be careful not to dig up the leater and also to not saturate the leather with the alcohol.

I had the seats apart to do this. The back section comes out and the bottom comes off the frame. Makes cleaning and re-dying much easier and there are fewer deep seams.

Taking all the dye offtook probably 4 hours and multiple passes. When finished, it was nicely clean but the leather had gotten hard from the alcohol. The next step, then, was using the Rejuvenator oil to soften the leather back up. This calls for saturating the surface, wrapping with plastic, and letting it sit for a couple of days. I did that twice. After each pass I cleaned the surface with their "Prestine Clean" cleaner. At the end, the seats were nice and supple again.

For a final prep, I used the Prepping Agent again with fine sandpaper like they suggest and cleaning with the cleaning stuff. If you're counting that's a start with Prepping Agent, two cleaning passes with alcohol, two passes with Rejuvenator and a final pass with Prepping Agent. It's work.

I applied the dye by spraying with a touch-up gun. They suggest diluting the dye with water but don't give any real direction. I used about 30% added water.

The spraying went well enough. Only a few drips to be seen. One mistake I did make was to put it on too heavy on horizontal surfaces. The instructions call for a dry mist (whatever that is) and I think going drier would have been better. First off, no drips and also the horizontal parts looked a little splotchy.

The Leatherique instructions talk about taking out imperfections with 1000 grit sandpaper. Nope. Doesn't work. It's hard to work down any drips without taking off the dye around them. It's not like taking off paint runs. I did a bit of that and touched-up with a small artists paint brush. Looks OK.

The instructions call for rubbing down the dyed leather. I did that in two passes with Prestine Clean. One the first pass the rages (lots of rags) got obviously burgundy-colored. The second pass not hardly any. This step also cleaned up some of the surface issues. Most of it looks great but it's not perfect like brand-new Porsche seats.

Pics!

Kevinkalhori

Hey I want to say thanks k you for writing this up and posting it here. I'll be doing this over the next few months and a great resource.