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Aficionado
08-30-2013, 08:57 PM
I'm putting five point harnesses into a C3 Corvette, which I intend to use for track day/autocross, etc. I've got Corbeau seats with the fifth slot modification for the anti-submarine belt. Currently have the shoulder belts on a harness bar and the lap belts on the factory mounting points (got Grade 8 hardware), but after looking at both the NASA and SCCA rule book, frankly, I'm still not sure what I need to do to mount the anti-submarine belt and have it be legal. I've heard just drill through the floor and use a big washer, but is this really ok...? Do I need to tie in a mounting point to the frame, or the seat bolts, or something else? Would love some real-world advice; I don't want to put the effort into fabbing something only to fail tech.

Many thanks....

Rod
08-30-2013, 09:38 PM
heres the SFI guidelines (http://www.sfifoundation.com/SeatbeltGuide06-05-12.pdf)

Aficionado
08-31-2013, 06:15 PM
Rod-

Thanks for taking the time to send that to me! That helps me with where I need to locate the mounting point. Do you have any idea where I could find the guidelines what sort of mounting is acceptable? Since I've got a fiberglass floor pan, can I just run a bolt and washer through, or do I need more?

thanks again-
JC

SLO_Z28
09-08-2013, 09:00 AM
Floor pan with washers is fine, and how most mount it.

parsonsj
09-08-2013, 09:38 AM
I would recommend you at least consider a 6 point system. There is even an approved way using the lap belt mount attachments for the under leg harness. 6 point systems are superior systems, easier to install, and 5 point systems will eventually be phased out by most sanctioning bodies.

Believe it or not: they are more comfortable too. :)

Aficionado
09-17-2013, 05:30 PM
Parsonsj--

I don't have any problem believing they're more comfortable, and will certainly consider an upgrade in the future. By the time I posted the question, though, I had already made that decision and had two pair of five-point harnesses as well as seats with the "fifth slot," to accommodate the single anti-sub belt, and a deadline to get it all installed.
How is that handled with the six point, since I'm having a hard time visualizing them going through the center slot? Do they just lay over the top of the seat?
On the anchor point, I wound up drilling a hole in the seat bracket (which is flat steel stock that bolts to the floor pan in the factory seat mount holes) and bolting the mourning tab to it. Hopefully that'll work.

-thanks for the advice!-
JC

vette427-sbc
09-17-2013, 09:09 PM
Take a look at how the factory inner buckles are mounted to the fiberglass... Its a plate with a nut riveted to the fiberglass, and then a cable bolted to that plate and then attached to the frame. That would be ideal IMO... I dont trust a bolt & washer going through the 'glass

Aficionado
09-19-2013, 07:35 PM
Take a look at how the factory inner buckles are mounted to the fiberglass... Its a plate with a nut riveted to the fiberglass, and then a cable bolted to that plate and then attached to the frame. That would be ideal IMO... I dont trust a bolt & washer going through the 'glass

Likewise, the washer idea, though I heard it suggested more than once, bothered me. One thing I considered was taking a piece of 1/4" flat stock about 2" wide and a door or so long and bolting it to the frame at the rear, running it forward to the outboard seat belt mount under the floorpan and drilling the stock so that the seat belt bolt ran down though it and was tied to it with a nut on the underside, and then locating and drilling a third hole for a bolt to mount the anti-sub belt, effectively tying the outboard seat belt mount and anti-sub mount to one another and the frame. And I may do that yet.

What I wound up with this time, though, was bolting the mourning tab to a hole in the rear crossbar of the seat belt bracket, which is a square made of welded steel and bolted down at all four corners to the factory seat mounting points. Don't you have Corbeau A4's? If so, you know exactly what I'm talking about. Think that'll clear tech?

Many thanks--subscribed to your build, btw : )

parsonsj
09-19-2013, 08:50 PM
Some good information here:

http://www.schrothracing.com/sdocs/2009_Competition_Instructions.pdf

Check out page 16, the Profi F-model and how the anti-submarining strap is connected to the lap belt anchor.

shortrack
09-20-2013, 08:53 AM
heres the SFI guidelines (http://www.sfifoundation.com/SeatbeltGuide06-05-12.pdf)


Thanks for posting that....!

vette427-sbc
09-24-2013, 07:58 PM
Likewise, the washer idea, though I heard it suggested more than once, bothered me. One thing I considered was taking a piece of 1/4" flat stock about 2" wide and a door or so long and bolting it to the frame at the rear, running it forward to the outboard seat belt mount under the floorpan and drilling the stock so that the seat belt bolt ran down though it and was tied to it with a nut on the underside, and then locating and drilling a third hole for a bolt to mount the anti-sub belt, effectively tying the outboard seat belt mount and anti-sub mount to one another and the frame. And I may do that yet.

What I wound up with this time, though, was bolting the mourning tab to a hole in the rear crossbar of the seat belt bracket, which is a square made of welded steel and bolted down at all four corners to the factory seat mounting points. Don't you have Corbeau A4's? If so, you know exactly what I'm talking about. Think that'll clear tech?

Many thanks--subscribed to your build, btw : )

Thanks! Good to see some other C3's around here.
I would think if you are mounted to the factory holes (or at least the same bracket) you should be good.

P.S. whats your username on CF or the other vette forums? I still cant figure out who you are so I check out your build :smashcomp

Aficionado
09-25-2013, 01:48 PM
Thanks! Good to see some other C3's around here.
I would think if you are mounted to the factory holes (or at least the same bracket) you should be good.

P.S. whats your username on CF or the other vette forums? I still cant figure out who you are so I check out your build :smashcomp[/QUOTE]

I occasionally post on CF as DropTopBigBlock, but I haven't been on there much since I sold my '71 454 car a few years ago.

I haven't started a build thread on this car; I'm doing a series on the build for 'Vette magazine, so they get the rights to the photos, etc. Those stories appear in the magazine, and then go up on the website (www.vetteweb.com) under my name, Jeremy D. Clough. The car is called "Scarlett."

Until recently I've done mostly a la carte work, such as brakes, adding nitrous, etc., with the goal of eventually doing a major rebuild with the obligatory LS and T56, etc., which we started in July. The engine build just ran in the magazine in three installments, and the teardown/swap articles should start appearing in a few months. This is my first real build, and I've got to admit I feel a little like Wiley E. Coyote after he tied himself to a rocket and lit the fuse. . .