Harness mounting options for street/track car?

[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

[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.

[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]

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

[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 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]

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]

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!

[BigRussia]

I did do my research hence why my only choice for a 4 Point harness was the Schroth ProFi ASM (ASM for Anti-Submarine), I would run 5-6 points if not for these having that feature. It's a feature Schroth is pretty proud of it seems, they have more details on how it works but it's similar to a factory 3 point in which one shoulder belt is designed to have your upper body go forward rather than slide down.

Anyway came to update; I ended up purchasing the BK Harness Mount Bar solution. While there weren't any Black Friday deals for it, one of their distributors had it with free shipping so I bit. Arrived Sunday, but just like my previous BK purchase it came missing some hardware. Already contacted BK and their product engineer was happy to help so they’re sending me the needed bolts soon. Will probably test it out next track day at Homestead in mid Jan along with the HANS III.

[SQ13]

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.

I had the same issue when I was running QFPs with stock seats, and I imagine that problem would persist with Nogaros. Maybe a shorter seatbelt receptacle would help?

[heinzboehmer]

I had the same issue when I was running QFPs with stock seats, and I imagine that problem would persist with Nogaros. Maybe a shorter seatbelt receptacle would help?

I do think that would help, but then I'd lose the pretensioner.

The pretensioner is actually why I wasn't super concerned about it before I installed the bucket and sub strap. When that fires, the harnesses will be pulled down towards the hips and away from internal organs.

[SQ13]

I do think that would help, but then I'd lose the pretensioner.

The pretensioner is actually why I wasn't super concerned about it before I installed the bucket and sub strap. When that fires, the harnesses will be pulled down towards the hips and away from internal organs.

That’s a fair point. I just feel more comfortable knowing that my harness is positioned correctly, without having to rely on the pretensioner.

[OldRanger]

Note: Different track organizations and club chapters may have different requirements for running harnesses. If possible, choose which track day organization you plan to get track time with and check the pre-requisites for using harnesses. You can get to this by looking for the pre-track inspection checklists. Where I live, on the same track/circuit, the NJ BMWCCA tech inspection requirements are different than National Capital BMWCCA, and different than Fridays At The Track (FATT). A minimum of a 4-point roll (bar) might be required to use 6-point harnesses.

6-point harnesses came with a bit of snowball-effect where I want to drive.

[Obioban]

Note: Different track organizations and club chapters may have different requirements for running harnesses. If possible, choose which track day organization you plan to get track time with and check the pre-requisites for using harnesses. You can get to this by looking for the pre-track inspection checklists. Where I live, on the same track/circuit, the NJ BMWCCA tech inspection requirements are different than National Capital BMWCCA, and different than Fridays At The Track (FATT). A minimum of a 4-point roll (bar) might be required to use 6-point harnesses.

6-point harnesses came with a bit of snowball-effect where I want to drive.

That’s how I came to the profi 2 ASM. I can run it as a 4 point or 6 point, in either case safely, depending on the requirements of the club in question.

[simonnim]

Obioban I just picked up the BK mounts from forum member. What do you run for the belt strap mounting? Right now I'm just using some generic seat mount adapter with the garagistic floor mount. But my seat mount doesn't have a place to attach a belt for clip in or screw in.