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Harness Mounting point

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Sun Apr 08, 2018 9:24 pm PostPost subject: Harness Mounting point
prophead
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Joined: 17 Jul 2016
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Location: Brightons, Falkirk

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Although this is not a competition car, just a track-day / fun car, where I'm making changes for safety equipment I am trying to use the MSA guidelines.

For the shoulder straps of my harnesses I want to put the eyelet bolt in point in a different location to get within a 25deg of horizontal for the shoulder straps.

I've measured and choose the location, and have the required size nuts captive on 3mm plate. I was lead to belive that I can weld these into position inside the car, as per the photo

https://www.flickr.com/photos/144556909@N08/shares/8AKss6

However, having referred to the Bluebook it looks like they want a reinforcing plate on the outside. In addition, with this location my eyelet bolts will be mostly in traction, not shear stress i.e. pulling mostly against the thread.

Before I commit to welding these in position, thought I would seek the advise of the more experienced.
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Mon Apr 09, 2018 8:13 am PostPost subject:
prophead
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Joined: 17 Jul 2016
Posts: 87
Location: Brightons, Falkirk

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Novice numptiness strikes again! Glad I stopped when I did and listened to my nagging doubt. Found the answers to my questions with some further research, just wish I'd done it before cutting some holes, at least I stopped before welding anything in place.

So, it turns out that these are spreader plates and should be on the outside of the structure and secured in position (but not necessarily welded) as once the eyelet or bolt is tighten the spreader plate is clamped in position. In addition, it is best practice to have the bolts / eyelets positioned that crash forces exert a shear force on the bolt rather than acting against the threads.

So, with this in mind I will repair the holes I made, and find a better position and orientation for the spreader plates and eyelets.

I'll leave this here for any other newbies that are scratching there heads over this stuff:-

https://www.tillett.co.uk/shop/documents/downloads/seat-belt-fitting-information-2012.pdf
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Porsche 924 GT8 track day car project
Golf Gti MK4 1.8t
Porsche 944 rolling resto - sold and sadly missed
Mondeo 2.2 tdci "the diesel sleeper" - sold
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Mon Apr 09, 2018 5:35 pm PostPost subject:
prophead
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Joined: 17 Jul 2016
Posts: 87
Location: Brightons, Falkirk

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Repositioned the harness mounts. The spreader plates now under the boot floor / shelf, eyelets bolted through and held with thick spring washers. The orientation will exert shear force on the eyelet as recommended, and the new position will comfortably get the strap angle in the safe zone. And I have repaired the damage done by cutting the holes in the wrong place and the wrong size - everyday a school day!

https://www.flickr.com/photos/144556909@N08/shares/604931
_________________
Porsche 924 GT8 track day car project
Golf Gti MK4 1.8t
Porsche 944 rolling resto - sold and sadly missed
Mondeo 2.2 tdci "the diesel sleeper" - sold
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View user's profile Send private message
 
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