Problem: My Volvo 123 GT has the original seat covers, internal foam and seat webbing. The covering material is very good condition but the old foam and sagging seat webbing make them less than comfortable.
Solution: Retain original seat covers ( mine are in very good condition) but replace the internal foam and replace the seat webbing. I decided to do this on the front seats only since these are where the real issue is. Restoration of back seat foam was not required for my car.
I completely removed the front seat bottoms and back supports. Next, I carefully removed the factory seat covers revealing the foam padding inside. It is always interesting to restore something like this since it likely has not been opened up since the Volvo factory in 1967. Removing the covers is straight forward. I took my time not to rip any material. The bottom foam sections are a set of foam pieces cut and sandwiched together using adhesive. The top back rests also are foam pieces but they are wrapped around the steel frame and adhesive is used to glue them to the frame. All foam pieces are in geometric shapes: squares, tapered rectangles, and strips. Most of the dimensions are simply squares with a few slight diagonal cuts.It is easy to measure and determine what is needed once you have them out.
Next, I carefully measured all the foam pieces: dimensions, thickness and grade of foam. A different foam density is used in a few places for more comfort. Specifically, the foam density used in the core pieces are denser than some of the top pieces. This makes sense since you want good support and comfort.
With all the foam out and measured, I researched new foam material companies and found a business called the efoam store. http://www.efoamstore.com. I am always a bit hesitant with some of these online businesses but they totally checked out and the total cost of the foam is not that much. They even have some good information on seat cushion foam as many others are seeking the same thing. I went through their online web ordering process for my pieces and ordered what I needed. The total cost for my foam was ~ 70 USD. I went with high density foam for all pieces except the top seats outside runners which give the seat a raised ridge look and help to keep you centered in the seat. For these I went with the next lower density ( this is very close to the original ). I have the exact order I used which I can make available.
When the material arrived, I set out to cut and glue everything together. I carefully compared the old seat foam to the new and made every piece the same. Note, the original foam was compressed with age and usage and no longer the factory original size, so I added a bit to my new foam dissensions ( no more than 1/4 inch in a few places ). To cut the foam I used either a long sharp razor knife (thin pieces) or a 'hot knife' (thicker ones). Finally, I used 3M adhesive to glue them all together. With the basic pieces together I still needed to glue the seat back to the frames. This took a bit of finagling ;)
With all the new foam in place and glue dry I slipped my original covers back on. This was a little more work with new stiff foam. The seat backs took the most work to get right.
Before putting the new seats back in the 123 GT I fully replaced all the seat webbing under the front pads. IPD sells a nylon web kit but my experience with these has not been good ( they end up being too stiff with no spring ). Instead, I used the original Pirelli material which can be sourced at a few places such as www.swedishtreasures.com.
The pictures show the final result. You can see the seats are full and expanded rather than sagging. I am very happy with results and now drive to San Francisco or Lake Tahoe ( 2 hr drives ) without any discomfort.
