Adding shoulder belts or rear seat belts to vintage cars
Safety is usually not on the list of vintage car advantages. The brakes on Plymouth Valiants usually need upgrades, crumple zones don't exist, side impact standards were decades away, and rear seat belts were an option for years! Front shoulder belts were a nuisance from their introduction in the early 1970s until 1974, when they finally reached the modern era (though they still tended to lock up too easily).
You can, with some work, add shoulder belts to front and rear seats. They may not be as safe as the ones installed in modern cars - but may be better than nothing. Proceed at your own risk, we cannot be held liable for the consequences of reading further.
Bill Watson wrote:
The front belts would have to be mounted on the "B" pillar, or on the upper door frame if it was a hardtop. I believe you would have to do some beefing up in the mounting area, especially in the case of the hardtop.
You could check the "B" pillar of a model with the shoulder belts already installed. You might be able use the bits from that car in the one you want to install the belts. This is something I have heard others talk about, but never heard what happened when they actually went through with it. Next time I visit the local yard, I'll have to take a closer look at the mounting hardware.
The floor mountings should be no problems as Chrysler had the floors drilled for belts, front and rear, from at least 1962. My 1965 Valiant has plates with a threaded bolt welded in place where the belts go (it only has front belts, but these plates are in the rear as well). My 1962 Valiant and Lancer have the holes front and rear with belts only on the front. There are no mounting plates, but the belts have a nut and bolt arrangement with a large round "washer" inside and out. The one under the floor is about 3" in diameter. The "washer" takes the strain in the case of an accident and spreads it over a larger area.
You could do something similar with the shoulders belts, just make sure they are round. The corners of square or rectangular ones could cut through the floor, or whatever panel the belts are mounted, in an accident. I suppose welding these plates/washers in place would also strengthen the support.
The reat belts, depending on their length, could be mounted at the same spot as the lap belt. Or, you could drill a hole through the floor in the area over the axle. This spot is higher than the floor where the seat is, and thus you would not need such a long belt. Also, the steel is thicker - just use a plate to add extra strength to the mounting point.
I cannot think of another point, unless you tried the wheelhouse, on a flat area. Again that would mean a shorter belt, but would need those plates to add more strength to the mounting point.
Some may consider it sacriledge, but I view it as being the same as installing turn signals on cars prior to 1955. They are a safety feature, and given the traffic these days, perhaps a safety necessity. The previous owner of my 1962 Valiant installed rear belts, and I will be doing the same with the other two. You have given me thought about installing front shoulder belts now, especially in the 1965. That one is my daily driver (or will be again when the new rear springs are installed).