I want to add seat belts in my 1950 Pontiac Streamliner but both the front and middle seat (presumably original) backs are sheathed in sheet metal that curves under the bottom edge. I could cut slots into it and fish the seat belts through to where they'd attach to the floor. But over time the belts will likely fray rubbing through the slots and maybe even be cut in the event of an accident. Besides filing the edges smooth and maybe folding the sheet metal over, any better ideas for eliminating sharp edges around the slots?
I'm a tin basher by trade and over the years several times I have used car door edge molding where odd shaped holes have had to be cut for wires etc. For smaller holes the trick I have found is to cut the molding longer than needed. soak in hot water to get it soft, apply, and then when it's cooled trim to fit. When the molding is hot you can curve into very tite spots.
No way would I cut the original seat panels. If using only lap belts you should be able to mount them on each side toward the rear. PS Good tip Tedy. This door edge stuff is useful for many things to protect fingers, wires, and parts.
I think this is your more serious problem. How are you planning to attach them to the floor? Seat belts are not simply attached with a bolt and nut through a hole in the floor, but rather are attached to a thick, wide, tapped nut welded to the underside of the floor. The floor itself is just made of thin metal that can't hold a threaded screw and is too thin to reliably hold a bolt and nut in event of an accident. The weld nut is the way the extreme stress that would be placed on the attaching point in the event of an accident can be properly dissipated over a wide enough area to prevent the bolt and the whole seat belt from being pulled off its mounting. I think this is the most difficult issue in attaching seat belts to a car that never had them and was never designed for them. How do you attach the seat belt to the floor in such a way that it will actually bear up under the load if it ever came to that? Of course, if you know all this already, I apologize for stating it again. If your car already has weld nuts in place, and perhaps 1950 models did in the event someone ordered seat belts as an option, then you're good to go. I don't know when seat belts began to be offered as options.
Yes, good points all. I was planning to bolt belts to a heavy cross member or plate steel. You're certainly right about the floorpan itself not being substantial enough to hold up in a crash.
This sounds like it would work fine. You just want to make sure that you're anchored to a point where there is a lot of thread. If you've ever removed a seat belt bolt from a car, you see that they generally have a fine thread and that pretty much the entire length of the bolt is contained within the threaded nut when it's fully tightened. All of that surface-to-surface contact between the threads on the bolt and the threads on the hole it sticks into make for a lot of stress holding capacity. Attaching to a thick cross-member or something similar like you've suggested should serve this purpose fine.
added 6 seat belts to my 59 chevy . there are specially designed washers for adding seat belts to a floor pan. they are large rectangular looking pieces with a special edge to resist tearing the floor pan in an accident. about $10 a set i think from autoloc
-Yep! Many seat belt kits came with those rectangular washers and directions on how to install them. That's what we have on several old cars. Don't know how well they work and hope to never find out!
