• slavie
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  • Registered: 2017-07-19
  • Posts: 8

Topic: Mounting crotch/sub straps with seat sliders

Hey guys, been ripping my hair out for a while here, figured it's time to ask for help.

Can the crotch/sub belts on 6pt harnesses be bolted directly to the seat bottom? And how so?
The SFI guide (https://www.sfifoundation.com/wp-conten … -05-12.pdf), bottom half of page two, specifies that it can be. But I cannot figure out whether the belt is supposed to go through the seat bottom then attach to the seat, or whether it's supposed to go on top of the seat and under the driver (the "Driver is sitting on the Crotch belts" part), which does not seem right.

I have double-locking seat sliders, adjustable seat back brace (the IO Port one), 5/6pt compatible seat. and it all works well for adjusting to different height drivers. However, the crotch/submarine belts on my 6 point harness is bolted to the floor under the seat and cannot be adjusted without climbing under the seat and loosening the straps, which is incredibly annoying to do in the pits with your helmet on. The difference between the shorter fatter driver and the taller skinnier driver is such that sub belt adjustment is required with this fixed position. This would be greatly alleviated if the sub belt mounting could be moved with the seat.

Thanks!

  • From: SF BayArea/Land of Enchantment
  • Registered: 2012-01-22
  • Posts: 903

Re: Mounting crotch/sub straps with seat sliders

There is a (painfully) simple answer to this problem......

Two (2) sub belts...One placed to accommodate the short guys,and one for the "slightly larger" humans..

I'd like to think I came up with this bit of brilliance,but the truth is I've seen it done many times before....

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  • slavie
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  • Registered: 2017-07-19
  • Posts: 8

Re: Mounting crotch/sub straps with seat sliders

BigBird wrote:

There is a (painfully) simple answer to this problem......

Two (2) sub belts...One placed to accommodate the short guys,and one for the "slightly larger" humans..

I'd like to think I came up with this bit of brilliance,but the truth is I've seen it done many times before....

Won't that require purchasing 2 harnesses to get the other sub belt and buckle? Also, the not-in-use buckle would just flop about potentially hammering your manhood (if so equipped)?

I guess it is a potential solution, though I'm really not a fan.

Any opinion on bolting to the seat?

Or even the seat mounting brackets? Schroth manual states that sub belts can be somehow routed to the lap belt mounts (https://www.tillett.co.uk/shop/document … n-2012.pdf), which to me means that it could potentially be bolted to the seat brackets.

  • From: Iowa
  • Registered: 2010-04-20
  • Posts: 2,660

Re: Mounting crotch/sub straps with seat sliders

Mount the sub belt to the underside of the seat with a crossbar that bolts to the underside of the seat.  There are options out there for this.   You still will have some variation in driver size and where the latch lands on the pelvis, but it will be much easier to deal with than two sub belts.

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5 Reply by hoverducky (edited by hoverducky 2019-03-26 09:40 AM)

  • Registered: 2010-03-08
  • Posts: 419

Re: Mounting crotch/sub straps with seat sliders

The single crotch belt is supposed to go under the seat in a five- or seven-point setup.

The driver-sitting-on-belts thing is an option for the paired crotch belts in a six- or seven-point system where you want to mount the belts to the lap belt anchors or similar.  This results in something like a parachute harness.  Useful for seats with a lot of layback, as it restrains your pelvis from moving forward and unburdens your naughty bits.  Doesn't do much to keep your ass in the seat, though, which is why a seventh belt is nice.

It is possible to arrange a seven-point harness in such a way that driver A is pretty much using the single crotch belt while driver B is using the paired sit-on-top belts.  The "unused" belts are still attached, but are not tight.  This can work because sliding the seat forward and back can effectively lengthen the belts at different rates because they are mounted in different locations.  Yes, this takes a huge amount of fiddling to get right.  No, it won't work for every (or even most) cars and drivers.

Oh, forgot to mention: Some brands of camlock support the ability to alter the belt to which the buckle is attached.  The internals of all five latch points are identical and the "fixed" belt has a pin or similar that prevents that particular latch point from opening.  So you can have the buckle either on the crotch belt or on one of the laps.  That makes the redundant crotch belt as suggested above a cheap add with lower ball-hammering potential. 

If you go this route, buy the second crotch belt in a different color than the rest of the harness.

  • From: Cleveland, OH
  • Registered: 2011-09-03
  • Posts: 2,227

Re: Mounting crotch/sub straps with seat sliders

I mean if we're in the buy whole new stuff range, just get belts that have an adjuster right at the buckle. That's what we did with our Crow 5 point camlock. Just have to remember to make it longer BEFORE you move the seat forward.

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  • slavie
  • Rookie Driver
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  • Registered: 2017-07-19
  • Posts: 8

Re: Mounting crotch/sub straps with seat sliders

TeamLemon-aid wrote:

Mount the sub belt to the underside of the seat with a crossbar that bolts to the underside of the seat.  There are options out there for this.   You still will have some variation in driver size and where the latch lands on the pelvis, but it will be much easier to deal with than two sub belts.

Got any links or pictures? Or are we talking a custom solution? This is actually the one I'm leaning towards right now: weld a brace that spans seat brackets, mount the sub belts to it. Solves a problem while adding strength at the same time.

Guildenstern wrote:

I mean if we're in the buy whole new stuff range, just get belts that have an adjuster right at the buckle. That's what we did with our Crow 5 point camlock. Just have to remember to make it longer BEFORE you move the seat forward.

Trying to avoid any more "new stuff". I have an FIA Schroth 6point belt that's only seen half a race so far, almost new. Besides, just dropped a grand on new halo seat, brackets for it, convex mirror, and some radio stuff...

hoverducky wrote:

The single crotch belt is supposed to go under the seat in a five- or seven-point setup.

The driver-sitting-on-belts thing is an option for the paired crotch belts in a six- or seven-point system where you want to mount the belts to the lap belt anchors or similar.  This results in something like a parachute harness.  Useful for seats with a lot of layback, as it restrains your pelvis from moving forward and unburdens your naughty bits.  Doesn't do much to keep your ass in the seat, though, which is why a seventh belt is nice.

It is possible to arrange a seven-point harness in such a way that driver A is pretty much using the single crotch belt while driver B is using the paired sit-on-top belts.  The "unused" belts are still attached, but are not tight.  This can work because sliding the seat forward and back can effectively lengthen the belts at different rates because they are mounted in different locations.  Yes, this takes a huge amount of fiddling to get right.  No, it won't work for every (or even most) cars and drivers.

Oh, forgot to mention: Some brands of camlock support the ability to alter the belt to which the buckle is attached.  The internals of all five latch points are identical and the "fixed" belt has a pin or similar that prevents that particular latch point from opening.  So you can have the buckle either on the crotch belt or on one of the laps.  That makes the redundant crotch belt as suggested above a cheap add with lower ball-hammering potential. 

If you go this route, buy the second crotch belt in a different color than the rest of the harness.

Trying to avoid overly creative solutions like twin latches or multi-murpose 7-point belts. Just sounds destined for confusion with multiple drivers involved. It is my view that things such as seat belts ought to have no room for error in a 24HoursOfLeMons demolition derby, so I'd rather spend more time fabricobling something in the garage then train a bunch of wild animals on which belts get used under which circumstances.

  • From: NH
  • Registered: 2010-01-20
  • Posts: 3,299

Re: Mounting crotch/sub straps with seat sliders

Weld in a strong horizontal brace under the seat that attaches to the sliders, not the seat itself. Your belts are supposed to attach to the cage/chassis, and your sliders should be strong enough that in a crash they do not break or break free from the car. The seat, well, there's always a chance the seat could free itself from the sliders. It shouldn't, but it could. So incorperate the anti-sub belt mounting into the sliders and mount it there.

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