siragan

iTrader: (1)

I'm putting a sparco seat with a 6 point RJS harness into my 7 for solo2 autocross, and I need a place to attach the shoulder straps... just like everybody else. Since I don't have a full roll cage, I need a harness bar. The question is how do I attach the bar to the B pillars of the car?

So far, I have been most impressed with this design:



The beauty of this design is that it uses the existing bolt hole in the pillar. However, it ALSO uses the bolt hole where the base of the seatbelt attaches to the floor. By using this design, it divides the force among a total of 4 holes instead of two, and when viewed from a free body diagram perspective, the forces those holes see are very similar to those that the stock seatbelts would see.

Essentially, to do this, you need a rigid bar connecting the two bolt holes in the B pillar, and then something CONNECTED to the bar that "floats" the bar in the air and attaches to the seat belt hole in the floor. This, in my opinion, is the RIGHT way to build a harness bar. I'm just not sure how to do it. Any suggestions are welcome.

jgrewe

iTrader: (1)

Good design ideas. The extra bars going down to the belt mounts in the rocker are needed especially if you have to make a "U" shape in the horizontal bar to clear your seat backs. Those keep it from acting like a jump rope and swinging up or down under a big load. Make the plates that will bolt to the B pillars and bolt them in. Fit the horizontal bar to those and tack it in. (Best to weld as much as you can without lighting your car on fire!) Then do the same with the lower plates and bars. Pull it out, finish the welds, paint, your done!

Rusty Shackleford

i looked at that and didnt like how you mainly just use it as a support since the floor mount on the floor is at a steep angle i like this bar that max7 made himself im going to also do somthing like that once i get some time at the shop

jgrewe

iTrader: (1)

Are those belts draped over the bar and attached to the floor? If so, make sure the bar is high enough to keep the belts from compressing your spine, shoulder belts are only meant to hold you back, lap belt holds you down. I would just wrap the belts around the bar, same height rule applies. There is a lot of metal in the B pillar where the stock belts attach, plenty to do the job, especially when you are spreading the load across the car.

Glazedham42

iTrader: (4)

Max7's design looks nice, but I wouldn't use it. It's too low, and would make your shoulders the fulcrum of the load, hence compressing your spine. The bar should be mounted well above the shoulders.

Re-Speed.com

iTrader: (3)

Here is how the SCCA GCR has you set up shoulder straps.

Gregs

ive heard its really unsafe to have the back straps mounted much lower than your shoulders, heard something about compressing your spine in a roll over

BigJim

i woudlnt trust the one rusty posted because with the mounts back so far in a rear end collision the back of the car will wrap downward, thus pulling those straps really tight on your chest. Just a thought though

TS87FC3S

reviving an old thread is max7 still around, any specs on this, im wanting to build something very similiar, just wondered how well it worked and what was used?