3rdBird

iTrader: (1)

So we're putting in a 10 point from Alston's Chassis Works, We're following the NHRA guidelines to make sure we don't have to do it twice.

My question is, what is the rule on a 5 pt harness, in relationship to the seat & driver.

I know the shoulder straps are anchored to the rear crossbar, but NHRA says the seatbelt has to draw a straight line from the cross bar to the shoulder of the driver. Does the seat belt go thru the top hole in the seat? BTW (plastic race style). If so then the line goes straight, then up over the shoulders.

or can the shoulder strap go around the seat?

Any pics or ideas?

JesasaurusRex

iTrader: (3)

yes through the hole, can't be lower than, i wanna say 4"s, than the shoulders

3rdBird

iTrader: (1)

cool thanks, I'll be there Saturday, unfortunately not w/ the new motor, but I'll run it any way.

AlkyIROC

I don't like mine to go through the hole in the seat. After going through the hole, the belts then go up and over the shoulder. Because they don't pull straight back, you can still lean forward slightly when the belts are pulled tight.

I have mine going over the seat. When the belts are pulled tight, they pull straight back and it's impossible for me to lean forward.

You will have to install something on the crossbar to keep the straps behind the seat. I use 2 exhaust/muffler clamps to keep the belts from sliding out on the bar.

The NHRA rules specify that when a person is seated, a line is drawn up the spine. This isn't always vertical. The belts should pull from 90* off this line from the top of the shoulder to 4" below. If you were sitting in a kitchen chair, the belts would be horizontal to 4" below your shoulder. At the far end on the other side of the scale, if you were flat on your back, 90* off your shoulder would be pulling straight down.

I have my seat mounted in a reclined position with the back of the seat sitting noticeably lower than the front. That puts the cross bar very close to 90* off my spine when the straps go over the seat even though the bar is lower than the height of my shoulder. A reclined seat also gives me more head room to clear the halo bar. It also created other problems because it also has me sitting back from the stock position. I refabricated a throttle pedal so I didn't have to stretch when the pedal was on the floor and I moved the shifter back and up so I could reach it when strapped in. I can just reach the switches on the dash when strapped in.

The only way going through the hole in the seat would work is if the pulling angle doesn't change. Remember, when the straps are pulled tight, you shouldn't be able to lean forward at all. If you can, then the shoulder straps won't contain you and as you lean forward in a crash. Your spine will be compressed as the belts force your shoulders downward when you lean forward.

3rdBird

iTrader: (1)

Well my cage passed tech last night, & the inspector even commended me on "my" idea of using muffler clamps on the backbar to hold the seat belts together. He said he has seen it done where a 3/8 bridge rides on top of the bar to retain the belts together.

"_____/________\______" obviously w/ a bar on the top, I just couldnt find the icon to complete it.

BTW I ran a 12.45 @106 w/ a 1.54 60'

Old motor comes out on Monday

Thanks for your help.

AlkyIROC

I've seen the bridge idea also and have considered it. I'm glad tech accepted the simple muffler clamp idea.