proper seat belt harness

[kickster]

I am installing a set of sparco sprint racing seats. I went to buy the seat belt harness but there are so many different types! Every shop advise contradict the other one. I am so confused.

I went to buy sparco clubmen 3 points seat belt and the shop owner refused to sell it since I dont have a roll bar in my car. He was pushing me to buy the 4 point belt.

What is the difference between these belts? can I use a 3 point belt in my car?
Why does the harness should be attached to a point at same height as my shoulder?

[AcidGord]

It really depends what you're going to use the harness for. For street use you should never use a harness without a roll cage in the car. If you should ever get into a major incident that involves your car rolling your body is held rigidly upright, especially with racing seats, and you're pretty much guaranteed to be seriously injured if not killed. As for the angle of the rear mount also consider the physics of the shoulder straps in a major incident. If your car rolls or experiences some other major vertical force the straps are going to pull downwards on your shoulders. Hello spinal compression damage.

CNAC and SCCA rules have very strict rules about the angle of the rear mounting strap in relation to the angle of the seat back. Don't have them handy right now though. They also are very strict about restricting harness use for Solo 1 in cars without cages I believe.

All of that said. I have a 3 point Schroth harness in my car that I use exclusively for Solo 2. The chances of a major incident are miniscule and it makes a BIG difference for holding me in place. (Even with my wild-ass off-course driving. :) ) But I left my stock belts in place and use them on the street at all times. Its just not worth the risk to me.

[kickster]

I see, how did you maintain your stock belt. I am using a racing seat and original belt mounts to OEM seat!!

[AcidGord]

I'm not using a race seat so all the factory mounting points are still there to be used. I just added the harness mounts to the bolts already securing the left and right OEM belts. Some harnesses can be installed using eye-bolts that replace the original mounting bolts as well. I have a bunch of URLs indicating various mounting methods at home. I'll send them along tonight.