Seatbelt/harness dilemma. Will 4 point crush my spine?

[INTMD8]

The car I'm building is a pillarless hardtop 4 door so adding seat belts is a bit of trouble. I experimented with having the shoulder strap mounting point at the roof but the angle is too severe no matter how far forward or back I have it on the roof line and the belt cuts into my neck.

So, my other option, which I would prefer is to retrofit 3 point belts directly into the original seats. These are from the 3rd row seat of an Escalade and they exit the top of the seat the same as I have them set up-






Now, I can make this happen but my only problem with this is it puts all the load on the seat itself. I can reinforce the seat frame and the floor pan of the car no problem, what I'm concerned about is will the original ball bearing seat tracks take the force of a crash or just blow apart? I don't see much of a way to make them stronger.

Last option is to run a 4 point harness. The car is not getting a roll cage, not really a good way to do it without ruining the functionality of the interior. These instructions show mounting them to the floor but most are saying that will end up crushing your spine in an accident. My question is, if the harness is draped over the top of the seat it would be going over my shoulder at the same (rather shallow) angle over my shoulders so in order for it to crush my spine it would also have to crush the entire seat frame.

http://wescoperformance.stores.yahoo...seat-belt.html
http://wescoperformance.stores.yahoo.net/am4point.html

I think with the way this car is built I would be dead in a high speed crash unless it had a full cage anyway, so should I just look at the belt/harness as a way of keeping me in the seat and not a 100% solution in a crash? I don't think any of these options would be good at 80+mph but if it was lower speeds, say 30-40mph would I not be better off not smashing the steering wheel? Btw, no plans on racing this car, it will spend 99% of it's time on the street.

Any input appreciated.

[frankv11]

Run seats with built in shoulder seat belt. Cts v and a few others have them.
You can get good deal at wrecking yard

[INTMD8]

Originally Posted by frankv11

Run seats with built in shoulder seat belt. Cts v and a few others have them.
You can get good deal at wrecking yard

I've considered that, the ones I like the best are newer Mercedes seats, just thought it would look strange to have all of the interior original and then late model buckets and a console.

[frankv11]

It's not weird, it's protouring

[FETorino]

Originally Posted by frankv11

Run seats with built in shoulder seat belt. Cts v and a few others have them.
You can get good deal at wrecking yard

Well you don't have to run the new seats but you could buy some tear them apart and use them as a template to design a proper frame mod for your seats.

[INTMD8]

Originally Posted by FETorino

Well you don't have to run the new seats but you could buy some tear them apart and use them as a template to design a proper frame mod for your seats.

Did that already Actually, I have the 3rd row seat out of my buddies rental Escalade all apart to see how it is built. I can reinforce the seat frame but it's the original seat tracks I'm worried about. (3rd row has no tracks).

I'm going to take a look at a few other tracks on seats with integrated belts to see if I can get an idea of built type/strength.

[Musclerodz]

Do not mount 4 point harness to the floor. it could potential collapse your back with enough impact load. Maximum downward angle should be around 15*-20*. Stick with the 3 point installation. If your going to autocross hard enough that you think you may need a 4 point harness, then I would be considering a proper harness bar for it as well.

[Vegas69]

You don't need harnesses for autocross if you have good seats. I quit wearing mine before I sold the car. Road racing is another story.

[GregWeld]

I tried to make about 2 turns with my '32 Ford Roadster on the RTTC autocross.... the first right was fine - then the quick left-hander that followed just about tossed me out of the car. No seat belts and a flat bench seat! Not good! The only thing that saved me was the floor shift handle!


We had this same problem in the '62 Bubbletop build --- so Rodger (Ironworks) found some Mercedes Benz seats that had the shoulder harness built into the seat back. Those seats have a monstrous cast aluminum chassis. Of course, we'd have just used the frame and we'd have had the seats built for a little more support etc.

[INTMD8]

Installing Mercedes CL seats would functionally be the way to go. The more I look at pics however the more I think I would have to modernize the entire interior for the seats to not look out of place.

I think I'm just back to having to reinforce the hell out of the original seat and integrate the 3 point belt, what else is going to look right here?-