Proper way to install shoulder straps to harness bar with eyelets

[325isBimmer]

I installed a roll cage in my E36 and I'm down to how to attach the shoulder straps to the harness bar. I attached a picture that I took a gusset and drilled a hole and bolted the eyelet to the gusset which I would weld to the harness bar. Not sure if there is a better method or if this would pass tech inspection. I plan on just doing normal track days so it doesn't have to pass tech but it would be nice to do it right anyway.

Thanks
-Mike

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[aeronaut]

That's not ideal IMO. Those eyelets being at 90 deg of the force that the shoulder belts will see, will likely bend, and allow the belts to add slack.
I'd figure out a way to get those eyelets in line with the belt ends. Welding a "U" shaped bracket might do the job.

When attaching to a harness bar, most belts wrap around the bar.

[mlytle]

What he said. They should wrap around the bar.

[Pat533i]

Looking at a website that sells them, it says they can be converted to a wrap style.

Im guessing you just cut in front of that buckle and wrap the harnesses as long as they have the adjuster piece.

Those bolt and clip style are most likely made for an open cockpit formula car.

[aeronaut]

Looking at a website that sells them, it says they can be converted to a wrap style.

Im guessing you just cut in front of that buckle and wrap the harnesses as long as they have the adjuster piece.

Those bolt and clip style are most likely made for an open cockpit formula car.

Makes sense you could convert them. IF they are long enough. Make sure they are long enough, before cutting the clip. And make sure you use the right adjuster/lock/thing.

[325isBimmer]

Thanks for all the fast responses. The belts were a package deal that I bought with the seats and I would definitely prefer the wrap around the harness bar style. I was trying to save another 1k in seat belts if I didn't have to. I will see if they are long enough to convert. Does anybody use the vac adapters for lap belt? I have those but not sure if I should get something different.

Thanks
-Mike

[Pat533i]

Those look really short! I don't think they're meant for a sedan. Only way I would run them (if they're even long enough) Is to get a long eye bolt that can be put completely through the roll cage bar. You should really just send those back and get the proper ones though.

[aeronaut]

Those look really short! I don't think they're meant for a sedan. Only way I would run them (if they're even long enough) Is to get a long eye bolt that can be put completely through the roll cage bar. You should really just send those back and get the proper ones though.

Holes drilled completely through the harness bar of the roll bar? No.

But yea, those shoulder belts are very short, probably not made for a production car.
I'd get different shoulder belts.

[Pat533i]

Holes drilled completely through the harness bar of the roll bar? No.

I only recommended that because it's right in the schroth installation guide as an acceptable method. Is it something I would do in my car, No.

[aeronaut]

I only recommended that because it's right in the schroth installation guide as an acceptable method. Is it something I would do in my car, No.

That really surprises me.
I'm pretty sure that would violate SCCA and NASA cage specs.

[325isBimmer]

I am on edge with buying new harnesses or drilling a hole all the way through the harness bar but add a pipe all the way through the cage and weld it on both sides then get a longer eyelet bolt. I found this posted somewhere that states the SCCA rule: SCCA manual says Holes in the roll cage to accommodate the
installation of the harness must be bushed and welded completely. So I am thinking if i add the pipe all the way through and weld it completely on both ends it will pass inspection. I am sure it will work and be safe just not sure on the inspection. I am only planning on doing HPDE events but still like to make the cage properly.

Thanks,
Mike

[Pat533i]

Racetech has 50% off harnesses right now.

[aeronaut]

Where those three pics taken without moving the shoulder belts? I probably missing something in the pics, but those belts simply don't look long enough. Could a large/tall person sit in the passenger seat and actually use the shoulder belt?
Drilling, bushing, welding, etc...or just buy the proper shoulder belts.

[Feffman]

When attaching to a harness bar, most belts wrap around the bar.

Aeronaut is correct. In the current April 2020 SCCA GCR manual on pages 75-76, it specifically shows how to properly wrap the shoulder harnesses around the cage.

Feff

[325isBimmer]

https://www.pegasusautoracing.com/pr...RoCrJcQAvD_BwE

I'm going to order these. Anybody have recommendations where to buy them from. Is it ok to use the mounts I have on my floor mounts pictured for the clip on style? Or do I need to add eyelets to the floor?

Thanks
-mike

[NeilM]

My Schroth shoulder straps are wrapped to the harness bar in the conventional way, but for reasons particular to my non-trailered car I've long been interested in the idea of converting them to a snap-in mount, similar to the lap belts. There's nothing inherently wrong with that — it's the conventional installation method for open wheel formula cars.

But there's no need to use an eye-bolt on the harness bar for that. Simply take a crescent shaped gusset piece, similar to the one the OP already has, but rotate it 90 degrees so that it's vertical. Shape the rear concave edge to match the curvature of the harness bar and weld it securely in place with full length weld fillets on both sides. Clip the harness fixture directly into the drilled hole in the gusset piece.

Bolt-in harness mounting brackets are usually about 5mm thick (see part B24 here, https://www.hmsmotorsport.com/produc...-brackets#2457), so consider that an absolute minimum material thickness. I'd be inclined to go thicker than that, to 5/16" or more. Size the contact edge with the harness bar generously, a third of the circumference or so, to allow a generous weld length. Drill the single clip-on hole as far in from the gusset's outboard edge as the end fixture on the harness will allow.

As long as you can both cut out the gusset pieces and properly weld them yourself this would be a $20 project, and that includes a rattle can of paint to make it look good.

I have no idea about race tech approval status, but this should be mechanically sound. There's no bending moment on the mount, just a straight pull.

Critiques/comments/suggestions welcome.

Neil

[aeronaut]

Agreed! That would work well. If, the shoulder belts are long enough as is.

[NeilM]

But there's no need to use an eye-bolt on the harness bar for that. Simply take a crescent shaped gusset piece, similar to the one the OP already has, but rotate it 90 degrees so that it's vertical. Shape the rear concave edge to match the curvature of the harness bar and weld it securely in place with full length weld fillets on both sides. Clip the harness fixture directly into the drilled hole in the gusset piece.

Neil

Turns out that these are already a thing — duh! They're pre-made, laser or plasma cut brackets used by chassis fabricators to mount shocks, suspension arms, etc. Google "weld on radius mounts" and you'll find things like this:



See https://ebay.to/2JUOjIb

This eBay seller offers many different sizes, and will also custom make. It'd be good to minimize how far the bracket sticks out (and put high density roll bar padding either side), since the bracket points directly at your seat back.

Neil

[325isBimmer]

Good idea, I haven't ordered the belts yet. I did just get done painting the cage though. I got it from roll cage components and fit and welded it in.20200411_142357.jpg20200411_142424.jpg20200411_142539.jpg
The shoulder straps are long enough. I still an thinking about different harnesses though

Thanks
-Mike

[NeilM]

Good idea, I haven't ordered the belts yet. I did just get done painting the cage though. I got it from roll cage components and fit and welded it in.
Thanks
-Mike

Looking good!

Nice vintage Honda Street Scrambler in the background.

Neil

[BKO 5]

Its worth mentioning that the shoulder harness should be mounted so that theres no more then 0- 20 degrees of angle on the (including HANS device) horizontal plane. This should actually dictate the way you mount them, if your already plan on welding some mounting tabs in this shouldn't be a problem.

If drilling holes straight through the harness bar it most definitely needs sleeves welded in on both sides. Although if harness angles are with in spec then wrap around is a hell of alot easier.

[325isBimmer]

https://www.armada-engineering.com/s...s-4-pack-copy/

Found these today, they look perfect. I think I'm going to order these. I did set the angle slightly up within 20 degrees

Thanks
-Mike

[aeronaut]

I have no idea if those will or will not work under high load. I will simply say the type that Neil posted will spread the load to the area of the pipe that can handle higher load (that is, the part of a round pipe that is parallel to the load).

[NeilM]

I rather like them. Here's the photo:



It's a bit hard to tell, but I think in real life they may be somewhat bigger than the photo makes them seem, in which case there ought to be enough contact length for a stout weld. They're intended for harness mounts, and made of 4130 chrome-moly.

Neil

[aeronaut]

Yea, it all depends on how big they are. Ideally, they need to be big enough to put some of the load into the the parallel part of the bar (in this case, put load into the top and bottom of the bar, and not just the front face of the bar). Even if the weld holds, if all the load is into the front face of the bar, it's more likely to deform.