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Old 01-07-2019, 07:10 AM   #1
haaken675
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5 point harness install tips

Hey everyone. I am finally getting my interior put back together on my car and want to make sure I install my harnesses in the most efficient and safe manor possible. I have a custom built 4 point roll bar, so no worries on putting harnesses into a car with no rollover protection. What I am curious about is what the best way to mount the eye bolts for the harnesses. I purchased cipher auto harnesses, and they came with what appear to be 7/16 eye bolts, so clearly not going to thread into anything preexisting in the chassis.

So a couple of thoughts. I could potentially find a graded set of eye bolts that fit in the rear seat bracket spot:


Or, I could drill holes and mount the eye bolts for the hip straps to the rail itself. I of course will have to drill a hole for the submarine strap regardless of how I do this.

Or, should I just bite the bullet and drill new holes in the chassis for the eye bolts and keep them off the frame rail?
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Old 01-07-2019, 08:45 AM   #2
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The harnesses should have come with instructions on where to put the mount points. If not (yikes), Schroth has information published on their site.

https://www.schroth.com/en/segments/...-tech-tip.html

Think about it this way: If the seat mount gets broken/dislodged in a crash, do you want your belts mounted to it?
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would be in depending on tip slant and tube size
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Old 01-07-2019, 09:10 AM   #3
haaken675
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That's partly why I was considering getting a new eye bolt that would thread into the stock seat rail holes. This part of the body seems to be reinforced rather then my drilling a hole and using backing plates. I think this would keep the recommended angles in place.

And no, no instructions provided. That being said, I just looked up some of the major sanctioning body rules as well as the schroth instructions.
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Old 01-07-2019, 09:34 AM   #4
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Yeah mine are threaded into the seat holes, don't know thread pitch off the top of my head. I drilled holes and used backing plates for the crotch belt
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Old 01-07-2019, 09:50 AM   #5
haaken675
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Yeah mine are threaded into the seat holes, don't know thread pitch off the top of my head. I drilled holes and used backing plates for the crotch belt
Awesome, looks like I'm making another run to hardware store today! They are m10 bolt holes, I just double checked with some brand new bolts I purchased yesterday.
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Old 01-07-2019, 10:43 AM   #6
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I would not recommend attaching them to the seat mount. You can safely attach the eyebolts with threaded backing plates. Schroth sells them.

https://www.schrothracing.com/produc...nt-plates#1612

There are very specific instructions on how to position and orient the eyebolts. Make sure to follow them. In my opinion, the stock seat seatbelt bar hole does not provide the proper angle for the lap belts (far too shallow). Not to mention the clips are going to have to wrap around your bracket, and will interfere with the bracket and possibly the seat as well. Here's an example of where mine are attached, it's well back of the stock bolt holes for the proper angle per Schroth's instructions (mine are on welded-on reinforcement plates): link
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Old 01-07-2019, 11:04 AM   #7
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I would not recommend attaching them to the seat mount. You can safely attach the eyebolts with threaded backing plates. Schroth sells them.

https://www.schrothracing.com/produc...nt-plates#1612

There are very specific instructions on how to position and orient the eyebolts. Make sure to follow them. In my opinion, the stock seat seatbelt bar hole does not provide the proper angle for the lap belts (far too shallow).
Agree 100%.

The stock seatbelt bar hole, while seemingly convenient, is the wrong angle and a poor location once everything else has been mounted and tightened down.

I apparently didn't take any pics of that part of my install, but it's essentially the same as DW's.
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would be in depending on tip slant and tube size
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Old 01-07-2019, 11:04 AM   #8
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Look at major manufacturers of 5 point harnesses for angles- from memory,
the lap belt should be at about 45 degrees and as unimpeded as possible
and the shoulder belts go about straight back, in as short a path as possible.

Plates in the floor are fine- there are reinforced parts of the pan in good locations,
and the pullout for a 4 square inch washer is far higher than your body can withstand.

t
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Old 01-07-2019, 11:54 AM   #9
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schroth says 60 degrees (plus or minus 10) for the lap belts. The seats sit inwards of the seat bracket, and the rear seat bracket bolt is pretty much right at a 50 degree angle and unimpeded… I am not referring to the seat belt hole were that bar bolted to.

If someone wants to send me some pictures of other setups I would love to take a look. I don't see tons of space to get the needed angle without pushing it wide which is not recommended either.
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Old 01-07-2019, 11:59 AM   #10
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Here's another picture of where my lap belt is [properly] mounted. There's absolutely no safe way you'd be able to mount the harness to the stock rear seat bolt. Note where the bolt is; almost vertically straight down underneath the lap belt pass-through and covered by the seat.

The inboard location is the same distance from the seat in both directions; on the tranny tunnel as seen in the other pic I posted.

[/url]
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Old 01-07-2019, 12:03 PM   #11
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this is one of my favorite idiot-proof documents for cage and harness things - https://24hoursoflemons.com/wp-conte..._v3_051817.pdf

(page 15 for harness info)
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Old 01-07-2019, 12:17 PM   #12
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Here's another picture of where my lap belt is [properly] mounted. There's absolutely no safe way you'd be able to mount the harness to the stock rear seat bolt. Note where the bolt is; almost vertically straight down underneath the lap belt pass-through and covered by the seat.

The inboard location is the same distance from the seat in both directions; on the tranny tunnel as seen in the other pic I posted.

[/url]
That's a useful pic, thanks. I thought that would be pulling the strap out to far according to what I was reading in the scroth instructions:
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Old 01-07-2019, 12:22 PM   #13
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There's not enough room in an E30 for that kind of (bad) angle.
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would be in depending on tip slant and tube size
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Old 01-07-2019, 12:28 PM   #14
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yeah, as soon as I thought about it that made a bit more sense. Work has me getting a migraine already...
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Old 01-11-2019, 04:01 PM   #15
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I used the Schroth plates for the crotch, OEM belt spots for the two sides and the roll bar cross bar for the shoulders. Looked and felt great when buckled in
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