1972 Blazer 3-Point Seatbelt w/ Roll Bar Options

[vespaholic]

I have a 1972 Blazer with the factory lap seat belts.
The truck has a roll bar.
I plan to never run the hardtop on it.
I'd like to put in 3-Point retractable seat belts in it using the factory lower holes and mounting the top part to the roll bar.
I'm going to a truck salvage yard on Saturday to look for something that might work.
Anyone have any suggestions?
Anyone do something similar?
If so what did you do?
I'm looking to do this on the cheap, so I'm not looking at the aftermarket companies for new belts.
Thanks in advance !!

[1rippen6]

Squarebody trucks should work

[vespaholic]

Thanks
I'll take a look tomorrow.

[hemi43]

Originally Posted by vespaholic

I have a 1972 Blazer with the factory lap seat belts.
The truck has a roll bar.
I plan to never run the hardtop on it.
I'd like to put in 3-Point retractable seat belts in it using the factory lower holes and mounting the top part to the roll bar.
I'm going to a truck salvage yard on Saturday to look for something that might work.
Anyone have any suggestions?
Anyone do something similar?
If so what did you do?
I'm looking to do this on the cheap, so I'm not looking at the aftermarket companies for new belts.
Thanks in advance !!

I did that exact thing. New seat belts are not expensive and that's what I would recommend. In fact, I installed the bar just so I could have the shoulder belt.

[vespaholic]

Sound good.
Thanks for the pics.

[NDM]

Originally Posted by hemi43

I did that exact thing. New seat belts are not expensive and that's what I would recommend. In fact, I installed the bar just so I could have the shoulder belt.

So you installed the bracket for the belt on the factory roll bar? I have been struggling with this decision for ever and I really want to put a double roll bar in and front and rear shoulder belts.

[hemi43]

Originally Posted by NDM

So you installed the bracket for the belt on the factory roll bar? I have been struggling with this decision for ever and I really want to put a double roll bar in and front and rear shoulder belts.

Factory roll bar? No such thing. I made my own.
For rear shoulder belts you will need to fabricate a "family" roll bar.

[truckster]

There are really only two options for shoulder belts in the Blazer/Jimmy. I used the roll bar and welded a small piece of flat bar onto the roll bar to thicken it where I tapped it for the bolt. The other option is to get a later-model seat that has an integral shoulder belt. The SMC used to fabricate the hard top isn't strong enough to serve as an anchor.

[NDM]

Originally Posted by hemi43

Factory roll bar? No such thing. I made my own.
For rear shoulder belts you will need to fabricate a "family" roll bar.

Understood. I was referring to the one that most people had as the factory one. My mistake. I think it was made by Hickey or something.

Originally Posted by truckster

There are really only two options for shoulder belts in the Blazer/Jimmy. I used the roll bar and welded a small piece of flat bar onto the roll bar to thicken it where I tapped it for the bolt. The other option is to get a later-model seat that has an integral shoulder belt. The SMC used to fabricate the hard top isn't strong enough to serve as an anchor.

I have some seats that I pulled from the yard. They colapse down quite nicely. They are the 2nd and third row seats from a mercedes r350 Suv. I planned to metal shape a roll bar using my acquired shaping talents that looks like this later model custom Blazer. I am not concerned with roll over protection that much but i am very much doing it to be able to install proper shoulder belts for the safety of my family. I want front and rear shoulder belts. My plan it to make a buck out of plywood and then form the metal using the buck. Here is that custom Blazer that I loved. I would make a front and back with tie in bars. I do not have a tubing bender but I do have metal shaping tools to do this type of roll bar.

https://www.streettrucksmag.com/a-pe...evy-k5-blazer/

[truckster]

It's an interesting concept. Just be aware that, without proper bracing, it may not have the strength to retain a full-sized adult in a frontal impact, where the shoulder belt is most important.

[NDM]

Originally Posted by truckster

It's an interesting concept. Just be aware that, without proper bracing, it may not have the strength to retain a full-sized adult in a frontal impact, where the shoulder belt is most important.

I planned to build the core out of heavy tube that is tied into the front and back. I will then make cosmetic peices aand body work them to make it look sexy.

[Tom Vogel]

I used these clamps fro Ballistic Fabrication to attach the shoulder belt to my roll bar.

[NDM]

Originally Posted by Tom Vogel

I used these clamps fro Ballistic Fabrication to attach the shoulder belt to my roll bar.

Wow! those look perfect t for the task.

[jaros44sr]

Tom thanks for the idea

Do they look beefy, well made?

I have 4 point harness, with anti submarine. Pondering this for a long time, and they look like the answer

[hemi43]

FWIW, those clamps are definitely not strong enough for seat belts. Great for holding fire extinguishers, but that's about it.

[jaros44sr]

Thanks for the advice, but if I could see how one is made I could reverse engineer for strength

[hemi43]

Originally Posted by jaros44sr

Thanks for the advice, but if I could see how one is made I could reverse engineer for strength

It's laser cut from most likely 1018 steel and the "hoops" bent up.
The problem with this design is that in a seat belt application all the force will be put right on the bent part of the hoops which looks to have a material thickness of around (1/8") X 1/4", and also, that area is further weakened due to work hardening when it was bent.
Tensile strength of 1018 steel is around 60000 PSI, so each one of those bent corners has a tensile strength of 1875 LBS.
If two of those corner fail, so will the seat belt. A car accident could generate 50G, so your 200LB body could weigh over 10000 LBS.
I could go on, but I'm sure you can see where I'm going with this.
Don't use these for seat belts unless you have a death wish.

[jaros44sr]

Originally Posted by hemi43

It's laser cut from most likely 1018 steel and the "hoops" bent up.
The problem with this design is that in a seat belt application all the force will be put right on the bent part of the hoops which looks to have a material thickness of around (1/8") X 1/4", and also, that area is further weakened due to work hardening when it was bent.
Tensile strength of 1018 steel is around 60000 PSI, so each one of those bent corners has a tensile strength of 1875 LBS.
If two of those corner fail, so will the seat belt. A car accident could generate 50G, so your 200LB body could weigh over 10000 LBS.
I could go on, but I'm sure you can see where I'm going with this.
Don't use these for seat belts unless you have a death wish.

Hemi, I agree with everything you said, makes sense

Just have to find an alternative solution

[hemi43]

Originally Posted by jaros44sr

Hemi, I agree with everything you said, makes sense

Just have to find an alternative solution

IMO, the best way is to weld a bracket on.
Not sure if you weld, but if you want I can make you a CAD file of a bracket that you can get waterjet/plasma/laser cut just about anywhere, and I would just email it to you.

[Tom Vogel]

Originally Posted by hemi43

FWIW, those clamps are definitely not strong enough for seat belts. Great for holding fire extinguishers, but that's about it.

You could pick my Jimmy up by these clamps.

[hemi43]

Originally Posted by Tom Vogel

You could pick my Jimmy up by these clamps.

Your body will weigh twice as much as your Jimmy in an accident.
I build race car components, and I don't think I'll be suggesting my customers to use these other than to hold a fire extinguisher.

[Tom Vogel]

Have you inspected the shoulder attachment that GM put in the tops for the shoulder restraint?

[JJH Jimmy]

I think the more important question is how is your roll bar mounted to the bed of the blazer? If the roll bar is just thru bolted into tub of the blazer that is going to fail way before any of those mounting clips will fail with the leverage of mounting the 3rd point of the seat belt to the top of the roll bar.

If i was mounting a seat belt to the roll bar my roll bar would be attached to the frame of the blazer or at the very least have backer plates that sandwich the tub.

[hemi43]

Originally Posted by Tom Vogel

Have you inspected the shoulder attachment that GM put in the tops for the shoulder restraint?

Which tops?

[truckster]

If you can't weld the next-best option is probably to drill and tap the roll bar, or to bolt through the roll bar.