Seat Rebuild Question

[5String43]

The bottom cushion of the driver's seat in my car is hopeless knackered. Cosmetically, the seat is in great condition, but the bottom supplies no support at all. I sit in it, it just - well, bottoms out.

A quick inspection indicates that the foam is shot, but that visually, at least, the springing medium seems to retain at least a modicum of firmness. It's not broken or sagging, or anything like that.

So here's what I'm wondering: For those of you who have perhaps rebuilt your car's seats, have you just replaced the foam pad? Or have you also replaced the springing medium under the pad? Is it worth it to do both? Or does it matter if you leave the springs alone?

[Jdub]

To prevent the seat material from permanent stretching you might push a pillow under the seat - something to support your weight until you rebuild. I am in this situation now and need a cheap way to redo with what are a decent set of seats overall.

[5String43]

Jdub, thanks for the suggestion. I just dug out a spare pillow from our linen closet, folded it in half and stuffed that puppy in under the driver's seat. Works like a charm, provides exactly the helper support the seat needs. It'll do nicely, at least for now. A brilliantly simple suggestion. Why didn't I think of it? Duh!

My question about foam and spring still remains, however.

[fintstone]

Several companies that specialize in Porsches sell formed replacement foam. Probably pretty pricey though. World Upholstery is one:
Porsche, 911 993 coupe targa cabriolet parts, leather seat upholstery, canvas convertible top, carpet, rubber