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GT3 Touring - Simple Harness Bar for 6 points belt

Old 01-14-2019, 05:31 AM
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gsd98jsh
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Default GT3 Touring - Simple Harness Bar for 6 points belt

I go to track a few times a year and like having the back seat area for the storage space. As much as I loved my GT3RS for track driving experience, I also needed more storage space on the back seat area, and wouldn't mind if the car is a bit less hard core than GT3RS. So I traded in my GT3RS for GT3 Touring. But after having the roll cage on GT3RS with 6 points belts on the track, I wanted to install the same 6 points belt for my GT3 Touring. But as many of you may know already, GT3 Touring is not ready for such installation. So I had a local body shop make a custom horizontal harness bar that will be connected to the suspension plate, thus allow to install 2 upper lines of 6 points belt system. Unfortunately the bottom 4 points are connected to the seat, not the body. Since GT3 Touring does not come up with the 6 points ready to install holes, I did not want to bother making extra holes on the body. The current installation holds my body to the seat pretty well. It is not ideal and perfect, but I am happy with the final outcome. I just thought some of you maybe looking into the similar installation and share for those who are interested.












Happy Track Driving~
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Old 01-14-2019, 08:01 AM
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KBS911
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Nice job! Looks very functional.
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Old 01-14-2019, 10:21 AM
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Read up on the dangers of spinal compression on a downward sloping harness like that... not saying you have it right or wrong, but I've always understood that as the slope of the shoulder harness increases, so does the pressure on the spine in a crash.
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Old 01-14-2019, 10:33 AM
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gsd98jsh
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Originally Posted by sgroer View Post
Read up on the dangers of spinal compression on a downward sloping harness like that... not saying you have it right or wrong, but I've always understood that as the slope of the shoulder harness increases, so does the pressure on the spine in a crash.
Wow, I wasn’t aware of that. I guess parallel up to the shoulder height is correct? In any case, the seat penetration hole location should help. But most importantly not getting into an accident is the most important thing.
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Old 01-14-2019, 11:07 AM
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CDinSing
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Very nice clean and simple design. Look on the Shroth web site and read the installation specs. A range 0 to - 20 degrees from horizontal is fine and will not cause spinal compression. I made the measurements and this looks to be in a location that is well within that spec. even for a worse case of seat fully back and harnesses in the top holes. You would need to verify that angle on real install before building or using one though. Stress loading for a two person 10g crash scenario would be good to have to verify wall thickness on the tubing and mounting plate.
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Old 01-14-2019, 11:10 AM
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Great job! Could you possibly get another bar made? I'd like a simple clean sweep if so.

Best Regards,
Dave
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Old 01-14-2019, 11:20 AM
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gsd98jsh
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Originally Posted by CDinSing View Post
Very nice clean and simple design. Look on the Shroth web site and read the installation specs. A range 0 to - 20 degrees from horizontal is fine and will not cause spinal compression. I made the measurements and this looks to be in a location that is well within that spec. even for a worse case of seat fully back and harnesses in the top holes. You would need to verify that angle on real install before building or using one though. Stress loading for a two person 10g crash scenario would be good to have to verify wall thickness on the tubing and mounting plate.
Yes, that is what I based on, within the spec angle. Thanks for the advice
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Old 01-14-2019, 11:23 AM
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Originally Posted by SCCAForums View Post
Great job! Could you possibly get another bar made? I'd like a simple clean sweep if so.

Best Regards,
Dave
I will speak to the body shop tomorrow morning, it is already 11:20pm where I am. I think they can reply back in English if you send them an email. In any case, it cost me total of US $500 for the custom made bar and the installation. But the bar itself shoould not cost that much. I will send you their email address tomorrow.

Last edited by gsd98jsh; 01-14-2019 at 11:48 AM.
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Old 01-14-2019, 11:47 AM
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On the shoulder strap geometry, if the distance from the shoulder to the bar is more than 20in then the straps should be crossed. There is also a spec for the spacing distance between the 2 straps on the bar. Check the Schroth instructions for the spec. You can use split collars or roll bar padding to control the spacing. For your substraps, I believe the bar at the rear of the seat is not intended for substrap mounting. There are some aftermarket bolt in sub bars available such as from Cantrell.
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Old 01-14-2019, 11:53 AM
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I like it, however I hesitate because... I was led to believe that you don't use a full harness without rollover protection. The reason being that in a rollover crash, your torso is locked in place with a harness leaving your neck exposed to any side forces. Where without the harness a normal 3 point belt would allow your torso to move in a rollover. Could be urban legend stuff, but it makes some sense on the surface. Maybe real experts can chime in.
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Old 01-14-2019, 02:13 PM
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tstafford
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Originally Posted by gsd98jsh View Post


Wow, I wasn’t aware of that. I guess parallel up to the shoulder height is correct? In any case, the seat penetration hole location should help. But most importantly not getting into an accident is the most important thing.
I'm with sgroer. Been told the same thing. Also been told that the straps should go through the holes in the seat but not touch them while they are on your body. The plastic creating the holes thru the seat doesn't provide any meaningful strength to help in a crash. But as others have said - I am only relying on what I've been told when I had my safety package installed in my .1 RS.
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Old 01-14-2019, 04:36 PM
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CDinSing
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Please guys, what you’re told or heard is fine but use real data if you want to build something to be safe. Here is the link to the Schroth installation web page which gives max 20 degrees. Also discusses the crossing of the belts over a certain length and that belts must be fixed and not allowed to slide horizontally. It also addresses the angle for the sub belt mounted under the seat. This isn’t a dark art. Take a minute and read the instructions.

https://www.schrothracing.com/docs/S..._Checklist.pdf
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