Harness mounting options for street/track car?

[heinzboehmer]

In verts, which have identical floor slider mount points to the coupe, 100% of the load goes to the floor (shoulder harness is built into the back seat.

Additionally, the sub strap mount requirements are super low (700 lbs? Going off memory). There’s a reason a hole in the floor (thin sheet metal) plus a washer is fine.

Fair enough!

[Obioban]

Wouldn't the shoulder belts increase load on the four seat fasteners if the sub strap is attached to the seat vs the chassis? In other words, with the sub strap bar, the shoulder belts will pull on the sub strap, which will pull on the seat. Whereas with the sub strap mounted to the chassis, the tension from the shoulder belts won't be pulling on the seats and therefore won't increase load on the fasteners.

In verts, which have identical floor slider mount points to the coupe, 100% of the load goes to the floor (shoulder harness is built into the back seat.

Additionally, the sub strap mount requirements are super low (700 lbs? Going off memory). There’s a reason a hole in the floor (thin sheet metal) plus a washer is fine.

[heinzboehmer]

With or without a sub bar, all of the load is going through the seat mounting points. It is true you decrease that load if you run the sub straps into the floor, but you are not increasing it over stock by adding a sub bar to a 4 point. if anything, you are more evenly distributing over the four slider floor bolts.

Wouldn't the shoulder belts increase load on the four seat fasteners if the sub strap is attached to the seat vs the chassis? In other words, with the sub strap bar, the shoulder belts will pull on the sub strap, which will pull on the seat. Whereas with the sub strap mounted to the chassis, the tension from the shoulder belts won't be pulling on the seats and therefore won't increase load on the fasteners.

[Obioban]

Interesting point on the sub strap bar, hadn't thought of that.

I find it super hard to adjust the quick fits correctly as a 4 point because they attach to the 3 point seatbelt receiver and that one side sits pretty high up. I can't get it tight enough on my hips so that the cam doesn't ride up.

Might be a body type thing (I'm a skinny dude), but it feels like most of the 4 point harnesses I've tried do not get tight enough on my hips.

And yes, agreed. If you put your harness on with the door closed, it's very likely that they're not tight enough on your hips. Correct procedure is to tighten the lap belts with the door open, forget to close the door, tighten everything else, realize you can't reach the door, unbuckle and then do everything again lol

With or without a sub bar, all of the load is going through the seat mounting points. It is true you decrease that load if you run the sub straps into the floor, but you are not increasing it over stock by adding a sub bar to a 4 point. if anything, you are more evenly distributing over the four slider floor bolts.

[heinzboehmer]

With a sub strap bar, I can see that. I feel like the sub strap should be anchored through the sheet metal. Those sub strap bars add load to the OE mounting points. At this point you're drilling holes in the floor.

I think a sub strap unnecessary with the quick fit pros although I never had to test them. I can't count how many times I've seen people adjust a 4pt incorrectly. You have to get the lap belt low over the hips and really tight, I consider it impossible to do that with the door closed. Then the cam doesn't ride up when tightening the shoulder belts.

Interesting point on the sub strap bar, hadn't thought of that.

I find it super hard to adjust the quick fits correctly as a 4 point because they attach to the 3 point seatbelt receiver and that one side sits pretty high up. I can't get it tight enough on my hips so that the cam doesn't ride up.

Might be a body type thing (I'm a skinny dude), but it feels like most of the 4 point harnesses I've tried do not get tight enough on my hips.

And yes, agreed. If you put your harness on with the door closed, it's very likely that they're not tight enough on your hips. Correct procedure is to tighten the lap belts with the door open, forget to close the door, tighten everything else, realize you can't reach the door, unbuckle and then do everything again lol

[bigjae46]

Yeah sub strap only works with the quick fit pros.

I don't think the sub strap defeats the purpose of them. It lives in the car at all times and just gets tucked underneath the seat when not in use. Adds maybe 10s to the install/removal process.

With a sub strap bar, I can see that. I feel like the sub strap should be anchored through the sheet metal. Those sub strap bars add load to the OE mounting points. At this point you're drilling holes in the floor.

I think a sub strap unnecessary with the quick fit pros although I never had to test them. I can't count how many times I've seen people adjust a 4pt incorrectly. You have to get the lap belt low over the hips and really tight, I consider it impossible to do that with the door closed. Then the cam doesn't ride up when tightening the shoulder belts.

[heinzboehmer]

Didn't know you could add sub straps to the regular quick fits. I'd think that kind of defeat the ease of removal feature.

Yeah sub strap only works with the quick fit pros.

I don't think the sub strap defeats the purpose of them. It lives in the car at all times and just gets tucked underneath the seat when not in use. Adds maybe 10s to the install/removal process.

[Obioban]

Didn't know you could add sub straps to the regular quick fits. I'd think that kind of defeat the ease of removal feature.

For everyone....here's a good video on the quick fits...

You can’t— I don’t have quickfits. Quickfits are not their only anti submarining 4 point.

https://www.schrothracing.com/item/p...ia-4-point-asm

[bigjae46]

My non quick fit schroth 4 point has the anti submarining shoulder give point (they make harnesses other than the quick fit with this), and utilizes the factory 4 point tensioner 😜

AND has a sub strap attachment point, if I want it.

Didn't know you could add sub straps to the regular quick fits. I'd think that kind of defeat the ease of removal feature.

For everyone....here's a good video on the quick fits...

[SQ13]

I’d suggest running a sub strap with your four points. The camlock on my QuickFit pros would ride up, and I imagine there would be some organ damage in the event of a crash.

[Obioban]

Better off with the quick fits than a 4pt harness.

No offense...but you really need to do your research. A quick fit utilizes the OEM tensioner which prevents submarining. In addition, there is a black box on the inner shoulder strap to allow the upper torso to rotate so the 20 degree thing isn't an issue. A 4pt has none of that - no anti-submarine system other than...how tight can you get your lap belts?

Here are the choices accepted by HPDE's - OEM, Schroth Quick Fit (show them the certs), and a 6pt harness.

My non quick fit schroth 4 point has the anti submarining shoulder give point (they make harnesses other than the quick fit with this), and utilizes the factory 4 point tensioner 😜

AND has a sub strap attachment point, if I want it.

[bigjae46]

Better off with the quick fits than a 4pt harness.

No offense...but you really need to do your research. A quick fit utilizes the OEM tensioner which prevents submarining. In addition, there is a black box on the inner shoulder strap to allow the upper torso to rotate so the 20 degree thing isn't an issue. A 4pt has none of that - no anti-submarine system other than...how tight can you get your lap belts?

Here are the choices accepted by HPDE's - OEM, Schroth Quick Fit (show them the certs), and a 6pt harness.

[BigRussia]

Yeah no Quick Fits for me, I already have the Profi ASM 4 point belts sitting new in their box, just waiting to get a proper mounting solution to install them. I also just purchased a HANS III device and post anchors for Black Friday to run with them.

But dang yeah I wasn't aware my ABE seat was actually compatible with the Quick Fits, everything I read when I first looked into them years ago was saying they were meant for factory seats. And since I had the rear seat belts already removed I had passed on them :/

But wont the shoulder belt angle be more than the 'safe' 20 degrees with them? That was the other reason I didn't get them, especially with the PP seats already having notoriously low shoulder holes. I would think they would still need a harness guide bar to not risk shoulder and spine injuries.

[Obioban]

From their website:

"Quick Fit harnesses are not approved for use with any fixed back or aftermarket seats with the following exceptions: The Cobra Nogaro and Recaro Pole Position ABE are approved for use with QuickFit harnesses in already approved vehicles."

https://www.schrothracing.com/item/schroth-quickfit

https://www.schrothracing.com/doc-sh..._seat_2021.pdf

It would appear I was wrong. Proceed 😜

(side note— despite having an approved seat (nogaro), I still choose not to use the quickfit because of the force directions involved)

[Thoglan]

I don’t think it’s he ABE is certified to use with the quickfit. As far as I know, the only fixed back seat that is is the Cobra Nogaro. Lots of downward facing forces that most fixed back seats are not designed for with the Quick fits.

So, I would not.

From their website:

"Quick Fit harnesses are not approved for use with any fixed back or aftermarket seats with the following exceptions: The Cobra Nogaro and Recaro Pole Position ABE are approved for use with QuickFit harnesses in already approved vehicles."

https://www.schrothracing.com/item/schroth-quickfit

https://www.schrothracing.com/doc-share/coc_recaro_pole_position_seat_2021.pdf