1977 308 GTB 21819 Door Panel Arm-Rest Restoration

Hi All,

I'm reupholstering my GTB door panels. I have removed the old vinyl and foam from the arm-rests and discovered there is a foam cushion inset to the fiberglass armrest. The DS rest is wasted (compressed and out of shape) so I want to create new ones with some sort of equivalent upholstery structural foam. Does anyone have an idea of what to use for this? foam insert shown on the right of these two pics. I was thinking of using some expanding foam that I could sand onto shape but I don't think it will hold up to the task of regular use. The original foam seems pretty rubbery and tough, so it will give and not crush like expanding foam would.

Hopefully someone has ventured down this path in one of these cars or another car and knows some industry specific materials. I looked on McMaster and I don't see anything that would work unless I get some rigid foam, which wouldn't fill the arm-rest cavity. Maybe a (very) high-density memory foam?

View attachment 3762960 View attachment 3762961

 

Update: I spoke to someone at Smooth-On and they suggested FlexFoam-iT! 7 I ordered a gallon and am going to do some trial runs, and if it looks good, I'll post some DIY photos. Fingers crossed.

 

No, I considered that. But no. It does not go back to shape. If you use that stuff, you will notice that it can dent. It doesn't reset. It just crushes. It's not made for this sort of thing. I spoke with tech support at Smooth-On and he said their stuff is what auto manufacturers use for arm-rests, cushions, etc. and it is also flame retardant and meant for automotive applications like this. I think they even have a DIY video on arm-rests. He cautioned me about watching the 8:1 expansion and making sure there is a back-flow vent path otherwise it could crack the fiberglass arm-rest shell. So I'll experiment a little. I think the fiberglass already has some openings underneath so there should be a path to relieve expansion stress inside.

The problem is that I will need to use a sharp blade (razor or X-Acto) to shape it. Hot-wire foam cutting won't work well since this material is FR rated. No biggie.

I should have it in a few days. I'll post back my findings.

 

Excellent! Seems I’m on the right track. I probably won’t make a mold. Especially since my ‘baguette’ looks like it met a steam-roller. So I’ll practice some mixes to get a feel for the expansion and forces and may pour it in with several layers. I assume it will adhere to itself. The tech said to use rice to measure the cavity volume in order to get the right amount of liquid for the 8:1 expansion.

 

Thanks. That's a nice mold. Is the box behind it to force back-flow? The mold is an interesting idea. My Driver Side foam is deformed but I might be able to make a mold like yours and then scrape the LH side to match. How is the foam for shaping? I haven't received it yet. Hoping I can use a grater or rasp type file and a razor blade.

 

Great idea. I ordered direct from the manufacturer. Once I get the foam, I'll play around and see how it behaves. I might try the same trick, but like I said, I'll need to scrape away plaster from the mold to get the correct shape for the left hand side. Thanks for the tips! Cool to see someone else has been down this path.