72 Duster 3 point seat belts

[xdrakk]

Hi Everyone,

I need to put in 3 point seat belts all throughout my 72 duster on order of my wife to have the kids in the car as well. I have buckets in the front, and I found this kit from Seat Belt Planet that seems to just bolt in:

1971-1974 Plymouth Duster Driver & Passenger Conversion Kit

However, does anyone have any experience with adding in 3 point seat belts in the rear, bench seat? The package tray looks like it has a slot for the belt to run through for the shoulder, but I am not quite for sure how to mount it. The car is in the body work phase so if I need to have anything welded into that for this, now is a good time.

Any experience or thoughts would be appreciated.

Thanks!

 

[Fgill]

as you may already know, A-bodies never had 3 point belts for rear seat, less it was late 75-76 4dr cars (maybe). So, any slot you are seeing in the rear package tray would not be designed for a seat belt. My guess is you are seeing the optional rear air/rear defrost vent/duct slot thats in every a-body.
Id suggest looking to hard mount the 3rd shoulder belt in the sail panel area (similar to most moden cars), but it has to mount to heavy structural metal, backed up by backer plate or similar, otherwise in an accident, it is simply going to pull from the mount/rip out. This leaves you with an issue for middle shoulder belt however, if you want all 3 seat positions to have 3 pnt.
My only suggestion there is to go back down to the floor, but there is no legit way to spread the dynamic loading. Package tray wont do it, in fact if not done right, that thin rear shelf metal may just cut a belt or crumple, under the right conditions. You may need to do something like a custom harness bar. They normally work/are sold for front seats running 4 & 5 point race belts, but its a thought. Mount in in the trunk just behind the rear seat back and your set.

 

[xdrakk]

as you may already know, A-bodies never had 3 point belts for rear seat, less it was late 75-76 4dr cars (maybe). So, any slot you are seeing in the rear package tray would not be designed for a seat belt. My guess is you are seeing the optional rear air/rear defrost vent/duct slot thats in every a-body.
Id suggest looking to hard mount the 3rd shoulder belt in the sail panel area (similar to most moden cars), but it has to mount to heavy structural metal, backed up by backer plate or similar, otherwise in an accident, it is simply going to pull from the mount/rip out. This leaves you with an issue for middle shoulder belt however, if you want all 3 seat positions to have 3 pnt.
My only suggestion there is to go back down to the floor, but there is no legit way to spread the dynamic loading. Package tray wont do it, in fact if not done right, that thin rear shelf metal may just cut a belt or crumple, under the right conditions. You may need to do something like a custom harness bar. They normally work/are sold for front seats running 4 & 5 point race belts, but its a thought. Mount in in the trunk just behind the rear seat back and your set.

That makes sense. I was hoping just to use the package tray to run it through and then mount it down to the floor of the trunk. I do see what looks like a duct area in the package tray, but there is a spot that has curved metal to not slice a belt. It looks like it was really meant for a belt.

Should I be looking at welding a bolt / nut up in the sail panel and run it down through that into the trunk floor for solid mounting like the standard lap belt?

 

[Fgill]

That makes sense. I was hoping just to use the package tray to run it through and then mount it down to the floor of the trunk. I do see what looks like a duct area in the package tray, but there is a spot that has curved metal to not slice a belt. It looks like it was really meant for a belt.

Should I be looking at welding a bolt / nut up in the sail panel and run it down through that into the trunk floor for solid mounting like the standard lap belt?

no matter where you mount the belt, if you run a belt thru the existing mopar a-body package tray, the tray will not support the forward/downward stresses placed on the belt under accident conditions. This is known as dynamic loading. The tray metal will either collaps, kink or actually severe the belt...probably all 3.
The metal there is strictly to support the cosmetic tray, rear speakers and the like. Its thin, weak, spot welded in and not up to the task. Even if you think the metal there isnt sharp enough to cut a belt, under the extreme stresses encountered in an accident, it can & will. I am assuming you want 3 point belts for passenger protection and not simpy looks?
Look at the lower rear seat belt mountings already in your car, they all have plates on the underside of the car. These are backer plates, big, heavy gauge, stress relieved, hardened metal, welded in place. They are this way not just to provide the seat belt mount bolts with sufficient thread material the DOT has mandated, but also to prevent tear out of the mount/bolt in an accident. I would try to copy that as closely as possible, its a proven design that meets minimum standards to retain the belt mounting point to the car, in the event of a collision.
I still think a custom harness bar of sorts is the better option. The pic shows a modern one and how it is used for front seat shoulder belt mounting. This is what they are used for. They mount to the structural sides of the car and have loading support bars vertically. This is all by specific design, not by accident, for good reason. The shoulder belts have to support the loading and in order to do that, they must be mounted correctly, otherwise very bad things happen, and youd be liable for that legally speaking. Good luck.