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19-Dec-07 Seatbelt Mounts Part 1

Adjustable 4-point seatbelt mounts



I promised a seatbelt article ages ago so it's time to make good. To keep the race-look and for additional safety, I decided early on to go with a 4-point safety harness instead of the more common 3-point restraints found in modern cars. That's why we carefully positioned the roll cage cross brace behind the seats to provide the correct mounting point.

ImageI really didn't know where I wanted to anchor the belts until the interior was in place, so I didn't weld any seatbelt mounts in place. I also didn't want to weld inside the car (near the fuel tank) at this stage and I thought it would be nice to be able to adjust the mounting points if needed, so I devised a simple mount using muffler clamps – 8 of them to be exact.

I made a little cardboard template of how I thought the mounts should be and ran it by Maury for his advice. He and the boys spent many years racing and have some great advice (as well as stories). He didn't see anything wrong with the idea as long as I didn't do the welding (I can take a hint) and that I use grade 8 bolts where the belts mount.
ImageMatt Richard welded 2 tabs to each clamp. I wish I could weld like Matt, but since that will never happen (I stand a better chance of making the next Olympics) I'm glad there are guys like him around to weld the important stuff like these. You wouldn't want a weld to break loose when it's the only thing keeping you from being airborne.
ImageI laid them all out on my cardboard trunk template to prime and paint them. It’s amazing how much work I do over a trash can.

I painted them red just because that’s the way I envisioned them in my head. They’ll be completely concealed when finished and the red makes them easier to see and inspect when you uncover them. While not NHRA legal, they'll be safe and fully adjustable on the role cage and should keep the bodies in side, inside.
Image
I used fine thread grad 8 bolts to pin the belts to the mounts. The belts have a plastic sleeve in the mounting hole that allows the belts to swivel when mounted. This plastic sleeve causes some slack in the connection. On impact, this slack could cause the tab on the belt to get a running start as it slams against the bolt. If the bolt is soft, it could shear it like a bolt cutter. Better safe than sorry.

Maury saw no safety issues with the 2 nuts that hold the clamp in place. It would take more pull than your body could ever put in motion to stretch the metal or rip out the threads. Keep in mind there are four of them at work with each belt.