O.K., John, here's the whole process of re-padding an old car seat.
The first 4 pictures are of an original seat back spring unit that is 82 years old. Take all the old padding off the spring unit, and measure to see how thick the original padding was. Replace the old thickness with slightly more than that. In this case, the old padding was 1 1/2" thick, so I used 1/2" Flex Deck over the springs, 1" foam over that, and a layer of dacron wrap which will compress to 3/4 of its original thickness.
The Flex Deck goes on the spring unit with hog rings. I leave it 1 1/2" larger than the spring unit, and then trim for the curved corners. Once the Flex Deck is on, turn the spring unit upside down over the 1" foam, and trace around leaving it just slightly larger than the flex deck. cut the 1" foam to size, and glue it to the Flex Deck. I use foam to foam glue for this process, not contact adhesive because the seat covers will hold everything in place.
Because these seat covers had padded channels much like how the original seat covers were done, and did not have sew foam on the inside, I put a layer of 3/4 ounce (approximately 1" thick) dacron wrap over the new foam. I chose 1" 2650 FR (fire retardant) foam to pad the seat springs for the seat bottoms, and 1" 2635 FR foam for the seat backs. Foam is described with a 4 number system. The first two numbers are the quality of the foam. 35 would be a very high quality foam. The second two numbers are the density or ILD of the foam. The higher the last two numbers, the firmer the foam. 50 density is considered firm, and 35 is considered a medium density. I used 50 on the seat bottoms because they get more wear and tear, and 35 for the seat backs so they would be more comfortable.
After the foam is glued down, glue the dacron wrap to the top of the 1" foam, leaving it about 2 1/2" larger all the way around. Once again, trim the dacron for the round corners. Flip the whole unit over, spray the dacron and the edge of the foam with glue, and press the dacron into place up against the edge of the foam and onto the flex deck. That's it. The dacron is there mainly to let the seat cover slip, which it would not do if applied directly to the seat foam.
No one lives forever, the trick is creating something that will.
Last edited by DanTwoLakes; 08-15-2012 at 08:01 AM.