5 or 6 point harness in an SPF?

[Dan]

I would like to swap my current Williams 4 point harnesses for 5 or 6 point versions.

I guess this has been done before but I could not find any detail pictures.

I am wondering where and how to attach the crotch strap, (I was thinking about adding a reinforcemnt plate under the seat pan area)

And how to pass it through the seat. Do I have to cut a hole into the seat?

 

[Rob Klein]

This is my current set up

 

[Dan]

This is my current set up

Are those 4 or 5 point belts? I can‘t make out the crotch straps in the photos

 

[Rob Klein]

I did 4 point but they come in 5 as well

Schroth Profi II ASM 4 Point Harness (Anti-Sub) at CMS – Competition Motorsport

Schroth Profi II ASM 4 Point Harness (Anti-Sub) from Competition Motorsport

competitionmotorsport.com

 

[Rick Muck- Mark IV]

Yes,

You will need to put an opening in the seat. And a reinforced mounting for the lower strap is a good idea as well.

 

[Dan]

I did 4 point but they come in 5 as well

Schroth Profi II ASM 4 Point Harness (Anti-Sub) at CMS – Competition Motorsport

Schroth Profi II ASM 4 Point Harness (Anti-Sub) from Competition Motorsport

competitionmotorsport.com

Thanks Rob. I know that much. I need more info on how to attach the crotch strap and how to pass it through the seat (if it comes up in front of the seat, it will be too far forward to do any good)

 

[Rob Klein]

I did not use the crotch belt, but I did drill a hole in the seat frame in case I wanted to add it.

 

[Rob Klein]

You can see where I threaded the seat riser

 

[Dan]

Yes,

You will need to put an opening in the seat. And a reinforced mounting for the lower strap is a good idea as well.

Ok, Just wanted to make sure that there is no secret trick. I’ll go that way then. Thanks guys!

 

[Rick Muck- Mark IV]

Thanks Rob. I know that much. I need more info on how to attach the crotch strap and how to pass it through the seat (if it comes up in front of the seat, it will be too far forward to do any good)

No, that will do no good. Imagine getting to 25 MPH and THEN having the belts connect with the goods!

 

[Terry Oxandale]

Is there an acceptable way to run the straps from the waist strap mounts, under the legs, and then up to the latch? The primary purpose is to keep from submarining under the waist belt, not hold the waist down. I would assume if sufficiently snug, the "sensitive" parts will be between the straps rather than behind them (ouch). Isn't this similar to how the formula cars do it?

 

[Chris Kouba]

Is there an acceptable way to run the straps from the waist strap mounts, under the legs, and then up to the latch? The primary purpose is to keep from submarining under the waist belt, not hold the waist down. I would assume if sufficiently snug, the "sensitive" parts will be between the straps rather than behind them (ouch). Isn't this similar to how the formula cars do it?

Not an SPF but this is what I do. The waist belt and sub belts share their mount bolt.

Is this threaded sheet metal??? I wouldn't want to rely on that for holding anything:

Ideally, there should be some sort of (double) shear mounting to it, not an axial load which will want to pull it out.

And if that's located where I think it is, Rick is spot on that it's way too far forward to do any good. The belts are meant to hold you in place, not catch you mid-flight.

 

[Rob Klein]

let's face it, if you crash one of these things on the road, your going to the morgue.

 

[Howard Jones]

Oh. Please read these instructions and follow them to the letter. Please. This is a life-or-death issue. Improperly anchored belts can cause life-ending spinal damage. Especially the angles that the belts form from the mount point to the contact point on the body.

https://www.schrothracing.com/doc-share/ea_8-2_2019-04.pdf

https://www.sfifoundation.com/wp-content/pdfs/guidelines-bulletins/Seatbelt%20Installation%20Guide%2006-05-12.pdf

The next is very good for a unibody car with no real chassis tubing. Note the size of the backing plates.

Frog Racing - Harness installation

Choosing a harness The rules are pretty much the same across sanctioning bodies (ARA/CARS/NASA/SCCA), a five, six or seven point unmodified safety harness of proprietary manufacture, meeting the specifications below, shall be fitted for both crew members: - FIA Standard 8853/98 or 8853/2016 - SFI

www.frogracing.us

Also, 5 is better than 4, and 6 is better than 5 as far as protection is concerned but the sub-belt should be mounted at the correct point under the seat and then fed through the cushion to the belt latch. NEVER over the front of the seat to the latch. Do this wrong and the belts will cause your spine to fold up in a shunt.

Also also, the mounts need to be able to withstand at least a ton or two of force. If you can lift the car from ONE of the belts then it is correct. REALLY! 3/8 grade 8 bolts at a minimum through the MAIN chassis rails, roll bars, or transverse rails of the same specifications as the chassis. Use big diameter (minimum 1 1/2 "diameter) extra thickness grade 8 washers and G8 lock nuts on the backside of chassis tubing.

Here is a video of a shunt where the seatbelts failed (China fake certification) BUT the same applies to a mount point failure.

Track car? Hahns?

I don't mean to sound like your mom but I did Tech Inspections a few times and you would not believe the things people don't understand about seatbelt installation. Worst case....... 1/4-20 nuts and bolt through the FIBERGLASS rear panel of a cobra to mount the shoulder harnesses!

 

[Dan]

Oh. Please read these instructions and follow them to the letter. Please. This is a life-or-death issue. Improperly anchored belts can cause life-ending spinal damage. Especially the angles that the belts form from the mount point to the contact point on the body.

https://www.schrothracing.com/doc-share/ea_8-2_2019-04.pdf

https://www.sfifoundation.com/wp-content/pdfs/guidelines-bulletins/Seatbelt%20Installation%20Guide%2006-05-12.pdf

The next is very good for a unibody car with no real chassis tubing. Note the size of the backing plates.

Frog Racing - Harness installation

Choosing a harness The rules are pretty much the same across sanctioning bodies (ARA/CARS/NASA/SCCA), a five, six or seven point unmodified safety harness of proprietary manufacture, meeting the specifications below, shall be fitted for both crew members: - FIA Standard 8853/98 or 8853/2016 - SFI

www.frogracing.us

Also, 5 is better than 4, and 6 is better than 5 as far as protection is concerned but the sub-belt should be mounted at the correct point under the seat and then fed through the cushion to the belt latch. NEVER over the front of the seat to the latch. Do this wrong and the belts will cause your spine to fold up in a shunt.

Also also, the mounts need to be able to withstand at least a ton or two of force. If you can lift the car from ONE of the belts then it is correct. REALLY! 3/8 grade 8 bolts at a minimum through the MAIN chassis rails, roll bars, or transverse rails of the same specifications as the chassis. Use big diameter (minimum 1 1/2 "diameter) extra thickness grade 8 washers and G8 lock nuts on the backside of chassis tubing.

Here is a video of a shunt where the seatbelts failed (China fake certification) BUT the same applies to a mount point failure.

Track car? Hahns?

I don't mean to sound like your mom but I did Tech Inspections a few times and you would not believe the things people don't understand about seatbelt installation. Worst case....... 1/4-20 nuts and bolt through the FIBERGLASS rear panel of a cobra to mount the shoulder harnesses!

Thanks Howard,

I absolutly agree and plan to add a correctly sized backing plate under the seat pan area.
But I also think that even if the crotch belt is not installed correctly, it will even in the very worst case not be any more dangerous, than running a 4 point harness.

 

[Howard Jones]

About sub belt mounting point importance at 7:45

 

[Dave Hood]

When I purchased my Superformance GT40, I felt very uncomfortable in the 4 point Willans harness they provided. Why they spec that I have no idea. I quickly replaced that with a G-Force 5 point harness. That gave me much greater comfort until I thought more about the 10 gallon fuel cells to the left and right of me....

 

[Dan]

When I purchased my Superformance GT40, I felt very uncomfortable in the 4 point Willans harness they provided. Why they spec that I have no idea. I quickly replaced that with a G-Force 5 point harness. That gave me much greater comfort until I thought more about the 10 gallon fuel cells to the left and right of me....

Could you share details about the installation. Where did you attach the crotch strap to etc?

 

[Howard Jones]

So I hesitate to post this. I don't intend to be sensational........ but............The belts gotta hold! He came out alive.....just.

 

[DaveC]

I did not use the crotch belt, but I did drill a hole in the seat frame in case I wanted to add it.

Maybe I missed it mentioned earlier, but remember that the 5th or 6th crotch belt is not designed to catch your crotch! It is designed to keep the lap belt of the remaining 4-point harness held down low on your bony pelvis! Otherwise the lap portion is not held down, you "submarine" under the lap portion, and your abdominal cavity takes the g's instead of your bony pelvis. Your pelvis will hold up relatively well to the restraint forces of an accident. Your abdomen will not (ie major internal bleeding, get me to an operating room before I die).