This article appeared in the Kappa Perfromance Forum and was written by JPM:
and the two in the back:
Make sure you remove any wire harnesses that might be attached to the seat:
Next, tilt the seat forward and remove the torx bolt that holds the seatbelt on. I can't remember the size off the top of my head. I think it was 43 or so. Anyway, if you don't have a torx bit to fit, a properly sized ALAN key can take the bolt out as well.
You can now remove the seat from the car and put it on a work table or clean area of the floor somewhere where you can tilt it back and not scuff the leather. If you have a seat height adjustment, remove the switch by prying out on the left side of the switch:
Then, pull the switch out and disconnect it from the harness. Tilt the seat back and remove the plastic clips from the front and rear:
The clips that hold the side on vary between models. Some have the same clips on the side that are on the front and back. Some are not so lucky and they have automotive push plugs that hold the sides in. If you take the push plugs off, YOU WILL BREAK THEM. There's a small chance you can get them off without breaking them but it's unlikely. Go ahead and buy some more: AUVECO Clip 11675
Ok, on to the next round. tilt the seat forward by lifting the
side lever and remove the 15mm nuts on the outside of the hinge area:
Keep one finger on the hook side that is on the seat foam as it has a tendency to separate from the seat itself and stay stuck together. If one area should rip off, use the upholstery glue to put it back into place.
Ok, now the culprit. look at your seat bottom. The leather piece that goes on top is flat. However, your seat cushion is definitely not flat on the bottom:
This curve in the seat causes the leather to stretch down into it's concave shape and it doesn't have anything to fill it back up with when you get up. Effect: Saggy leather seat issue.
The cure is easy. You need to level out the concave area. Start by cutting a shape out of the foam that matches the seat. It just has to be close. Let it be larger than you need to so you can trim it down on the seat. Using the upholstery spray, cover the seat cushion and one side of the foam. Let it dry a bit and get tacky, then stick the two together:
Use the razor blade to trace around the actual seat foam cutting the new foam to its identical outline.
Next, grab your 60 grit sand paper and put it on a flat stick like a paint stick that is no longer than the section of cushion that you're working on.
Now, using back and forth motion with the sand paper, level off the new closed cell foam. Since it's a concave shape with the seat, only the sides will get flat and the center will still dip down:
When you've flattened the new foam so it's level with the front and back of teh concave seat (when you've reach yellow foam on the front and rear edge), start the process again filling the small concave area with a small piece of foam and start leveling off again with the sand paper:
After about three layers and lots of sanding you've got a perfectly flat seat cushion:
BTW, the yellow stripes between each section is the glue that was used.
So, if you have a new seat with minimal sag, you've done it. Put the leather back on pushing the corners down on the Velcro and reinstalling the seat in the reverse order. If your seat has considerable sag, you might want to add additional foam to it. However, don't add anymore closed cell foam. This is high density foam and you want to be able to put your seat cover back on with no problems. The best thing to do is to get 1/4" headliner foam from your local fabric store such as this:
Add one layer if your seat is not bad off yet or even two layers for 1/2" extra thickness if your seat is really sagging. This last layer of soft foam will let your seat feel comfortable and it will spring back up to keep the leather from sagging down once you get out of your car.
As a note, this can only be done on the driver's side. The passenger side is already flat b/c of the airbag weight sensor.
Ok, so that's it. You've all graduated JPM's upholstery clinic. Come back next week where I teach you how to make your own fuzzy dice