[flash]

yeah - you might get it past a DE tech, but a racing inspection steward almost certainly won't pass a 4 bolt pattern, in the factory installation, in that screw size. they will want either 4 in the rear and 2 in front in that size, or require welding in place, or larger hardware if only a 4 bolt pattern, or, you will have to drill through and add backing plates. it's not the screw size as much as the material around the nut.



basically, in a forward collision, most of the force is transferred to the 2 rear mounting bolts. the harnesses are a secondary restraint mechanism. the seat gets the initial load. in the factory setup, using only 2 in the rear can result them ripping out and sending you forward.

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[pmcrespo]

It will pass inspection. Refer to the CCR. In a forward collision the harness is the primary.

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[flash]

check again. i looked briefly at SCCA, which is the largest governing body, and the one the others tend to follow, and there is a hardware spec that requires a certain thickness of material at the floor for a 4 bolt setup, using 8mm bolts, and our floors are not thick enough.



this one dates back a long way too. i had to change my setup in the mgb 25 years ago for the same reason.



again though, it's going to come down to how observant and on top of his game the inspection steward is. a lot of them are not all that informed, and pass things they shouldn't.



more importantly though, 4 8mm bolts in the OEM captive nuts, using the OEM floor thickness, is not safe. so, it really doesn't matter if you can get away with it or not. it's a bad idea. that's exactly why porsche didn't do it, and they aren't talking about the kinds of speeds and such in racing.



rule of thumb, NEVER reduce any hardware size, quality, or quantity from that of stock when setting up for racing.

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[pmcrespo]

One additional item for PCA Club Racing (if you intend to get race teched with them) is that they will look for a "system" install and like to see both the seat and the bracket bought as a package with a receipt showing that the bracket is no older than the seat. They will make exceptions but these are becoming less common. They will also make exceptions to "home made" brackets and/or major installation hardware but these will be grately frowned upon and deeply scrutinized. I personally drilled new holes in the new brackets to match the 968 bolt pattern. Passed with flying colors....

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[flash]

somewhere around here i have a shot of a crashed car that used the factory mounting points, but fewer of them. it wasn't pretty. seat ripped out of the floor. driver got really messed up.



i generally hate the safety regs, and try to get around a lot of them, since i prefer to drive a topless car, and continually fight battles with stewards over things, but there are a few areas where i don't mess around when it comes to safety. this is one of them. reducing by half the strength of something that is already only intended for street duty, and then subjecting it to twice the stress of the original use, is exactly the opposite direction one should go.

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[Cloud9...68]

OK, great info, but I'm getting lost. Could someone please walk this very green sub-rookie through what needs to done here? Obviously the shoulder straps will attach to the harness bar, but could someone please walk me through exactly where the two lap belt and submarine belts need to mount, including the type of recommended hardware? Initial use of the car will be track days, with the goal of eventually racing, but that will involve getting around some very challenging logistical issues which are largely out of my control, so there's no telling when it will happen. Might have to wait till the kids are out of the house, but we'll see. Thanks.



Flash,



I just read through your post more closely, and my life is flashing before my eyes. Are you saying I shouldn't use the stock captive bolts to mount my seat? So I spent the entire weekend figuring out how do do this for nothing?! So what am I supposed to do? And as a general bit of major whining, how is someone working on a project like this supposed to know this kind of stuff ahead of time, and not end up wasting massive amounts of time on something, only to have to start from scratch and to it all over. VERY frustrating!!!

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[flash]

lol - try setting up a 60 year old british sports car. it generally takes 4 trips to the steward to get signed off on a new car.



i left you a message. ring me up.

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[pure&simple]

Instead of fussing with sub-strap mounting points, you could just use a different type of harness. The TeamTech jet pilot harness is a 6-point that mounts like a 4-point. Instead of having two straps run from the lap belt between your legs down to the floor, the straps wrap around your legs like a climbing harness. As a casual climber, this seems like a superior design to me. Not sure legality for racing or any of that.

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[Cloud9...68]

[quote name='pure&simple' timestamp='1363717974' post='140270']

Instead of fussing with sub-strap mounting points, you could just use a different type of harness. The TeamTech jet pilot harness is a 6-point that mounts like a 4-point. Instead of having two straps run from the lap belt between your legs down to the floor, the straps wrap around your legs like a climbing harness. As a casual climber, this seems like a superior design to me. Not sure legality for racing or any of that.

[/quote]

Sigh... Too late - already ordered a 5-point harness. So, is drilling a hole for a sub-mount another 12+ hour job, like everything else I've tried doing on this project lately? Sorry, feeling a little bitter after the recent seat install debacle...

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[pmason]

The seat I think is fine, in mine its bolted to 4 of the capture nuts, this the belts that is in question.

You should get a 6 point as P&S suggested, you have two shoulder belts that mount the the roll bar, you have two lap belts, one mounts to the stock location (outside), the other one is where your going to come up with some mount or drill a hole in to/next to the tunnel just behind the seat, and they the two sub belts which mount under the seat, here again you either going to need to drill two holes in the floor or come up with some other means to attaching these.

If you do some searching of the harness manufactures sites they should include some instructions.

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[flash]

pca is really weird about this. they have no requirements for i can find seats in the rules. at least they finally outlawed aluminum lug nuts.



nasa requires a reinforcement increase to .090"



scca requires a lot more stuff



in any case, using less hardware is a BAD idea.

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[pmason]

I haven't looked in this & last years rules but I do race with the PCA. The only thing I remember is the expired seat needs a back support.



Reminds me, I need to go get my physical and mail in the license renewal.

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[flash]

yeah - pca is pretty lax. but then, they're not going as fast as other organizations, and they're more worried about scratching their paint than really racing, so i get that they can do that (ducking)

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[pmason]

Yea but I don't want to be beating out fenders every weekend either :-)

I was going to join NASA also but after watching them and having friends race with them, their cars looking really nice at the begining of the season and at the end all banged up. If I wanted to do that I would race spec miata/pinata :-)

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[flash]

you need to expect to replace most of your race car every 2 years if you want to be competitive. definitely new body work, paint and a new motor every year. that's racing. otherwise you're just spending money to frustrate yourself, unless you enjoy losing.

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[Cloud9...68]

Guys,



I really appreciate the suggestions and the discussion this topic this generated, but in case I haven't been clear enough about this, I'm not going door-to-door racing in this car anytime soon. Maybe in a few years, but not in the foreseeable future. This car will be used for track days at the local driving academy, and then I may join the "country club" type track about 15 miles from my house. It will also have to remain streetable for awhile, further precluding competitive racing. And there's no way I can afford the level of upkeep Flash describes in post 55 while I'm solely supporting a family of four. The guy who's going to be installing my roll bar just offered me a seat on his chump car team - that may be plenty to satisfy my competitive juices for the time being.



That being said, I think I'm perfectly fine bolting the seat mounts to the existing captive nuts in the seat runners. I am a little uneasy about the fact that the mounts aren't long enough to capture the rearmost nuts, so I think I'll have extensions welded to them, allowing me to use all six nuts. Given that the seats will be effectively bolted directly to the floor, without the instability of the runners used in the stock seats, the set-up will be plenty sturdy, especially since it's highly unlikely that I will be banging into anything (at least any other cars on the track) for some time. And the beauty of this is that I can always redo it later, for when and if I do go racing.

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[flash]

pick up the phone. i think i have a simple solution for you.

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[pmason]

I'm sure others would agree, the main point, which I don't think was ever called out, don't be cheap on safety.

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[Cloud9...68]

Agreed, safety is paramount. But I aslo want the safety measures to be appropriate for the application. When I eventually go racing, I'll of course (per the rules) install the stoutest possible full cage, and may at that point come up with a stronger attachment for the seat. But for the practice session/DE work that's in my foreseeable future, I don't want to be lugging around a heavy cage, especially considering that most of the cars I'll be sharing the track with will be bone stock, at least with regard to safety equipment. So I plan to take an incremental approach, starting with a weld-in roll bar/harness that's being designed to be easily upgradeable to a full cage. I'm going to modify the seat mounts to lengthen them enough to capture all six of the captive nuts in the floor, and I'm going with a 5-point harness, including a sub strap bolted to the floor. But I'm keeping my stock retractable belts for when I drive it on the street.

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[flash]

i think that is all reasonable. as i said on the phone this morning, i think if you add the strip underneath the rails, so that you reach back and grab the rear nuts, you'll pass any inspection.



have fun

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