Does the vinyl of the Backpad get glued (contact cement) to the backer board? The portion hidden behind the seat.

Mine is detached and floating off the backer board but is retained on the sides.

Thanks,
Sean

Yes.

Thanks Mark.

I made repairs to the pressboard and they telegraphed through. Wish I had put a layer of 1/8” foam underneath the vinyl

Even the NOS pads from Porsche come this way. They should have used a better glue.

Weldwood contact cement. Available almost everywhere. Two light coats on each surface. Use a cheap foam brush. Let it dry at least 2x what it says in the directions. Press together and you’re done.

*contact cement must be completely dry before you press surfaces together. Better to wait an hour longer than you think than to do it 5 minutes too little. Wet contact cement re-activates dry contact cement so let everything dry thoroughly.

@mepstein , What do you use to remove the 50-year-old residue from the first cementing?

I would use 3m spray trim adhesive, one does not want the glue thick in this area

I don’t. Well, really it depends. Sometimes the old residue just brushes/scrapes off. I’ve hit some parts with a wire wheel. When I did new upholstery on my 914 seats, I just went right over the old. Worked perfectly. But I’m no upholsterer or expert on contact adhesive.
I have found that most of the 3m stuff doesn’t have the hold that we’d expect, especially when it gets hot in the car. Weldwood comes in small and large cans and while pretty inexpensive, seems to be the go-to for a lot of contact adhesive needs.

I’m assuming the OP was talking about gluing the excess material to the back of the back pad. I don’t think the glue really shows on this spot. If I misunderstood, I’m sorry. I’ve tried other brands of spray adhesive and they don’t hold well. But I have limited experience with upholstery.

3M doesn't like the heat. A while back I posted a link to a video of this old upholstery guy stating that very same thing. He also recommended NOT brushing on Weldwood cement but to spray it with a $35 HF syphon cup gun. Leave it in the paint gun if you plan on using it again in the next few days. Just wipe the exterior tip clean before you start. This stuff is the best I've found in a rattle can. https://www.amazon.com/dp/B017I6I4RE?ref=pp...etails&th=1 I used it on my old plane's interior and it never separated. Hop in a low wing aircraft after it's sat on the tarmac. They get much hotter than a car.

Here you go:
https://www.youtube.com/watch?v=2KzEb2ZvWzo&t=1s

https://www.youtube.com/watch?v=c9Rka9Bdc14&t=771s

I agree with the statement about 3M spray adhesives.. when I use spray adhesives, I only use the 'industrial grade' #90 by 3M, but even then it doesn't necessarily have my full confidence. Also, in my experience with the sprays and the brush on contact cements - humidity plays a big role in their performance, at least initially. They don't like it. Also, I've notice that the original backer panels have brush strokes where glue was applied - and also it was not applied thoroughly either!! They did a terrible job with it imho. So the factory wasn't spraying it on apparently, maybe they should have.. as some of the carpeting was sprayed in places and generally did well.

.