43 replies to this topic

[Jim Boemler]

Seat supports shall be of the type listed on FIA technical list No.12 or
No. 40 (lateral, bottom, etc)

The writing isn't totally clear, but I read that section to refer to "Seats homologated to and mounted in accordance with FIA standard 8855-1999", rather than all seats. For instance, I don't think anyone has postulated that all seat back braces must conform to an FIA standard, have they? By your reading, that would be the case.

[Mike Collins]

OK, so I will try to be clear. The picture above shows NEW METAL welded to the stock seat sliders. The seat in NOT attached to the stock sliders it is attached to that new contraption.

I cannot possibly tell you how many crappy seat installs I have seen.

Does your seat have built in bolt holes in EXACTLY the same place as the Mazda Miata Seat?

[Steve D]

The writing isn't totally clear, but I read that section to refer to "Seats homologated to and mounted in accordance with FIA standard 8855-1999", rather than all seats. For instance, I don't think anyone has postulated that all seat back braces must conform to an FIA standard, have they? By your reading, that would be the case.

Just so we're all reading from the same sheet of music, here's the FIA Standard 8855-1999:
http://argent.fia.com/web/fia-public.nsf/6CC535B9F4ADFF76C12574430035205F/$FILE/Competition_seat.pdf
"1.1 The seats shall be rigidly fixed to the test rig using the attachment points and supports foreseen by the seat manufacturer."

FIA Technical List 12:
http://argent.fia.com/web/fia-public.nsf/27810E5EA3E1EAF2C12579260051FBF5/$FILE/L12_Approved_seats.pdf
(in which the type of support(s) is specified (i.e. lateral, bottom, and/or back), not a specific part number)

FIA Technical List 40:
http://argent.fia.com/web/fia-public.nsf/5ECFD8C3F57FC75BC125791A0047CC7C/$FILE/L40_Approved_Advanced_seats.pdf
(in which the specific support part numbers are specified for the listed seats)

Back to your regularly scheduled argument.

[Mike Collins]

Just so we're all reading from the same sheet of music, here's the FIA Standard 8855-1999:
http://argent.fia.co...tition_seat.pdf
"1.1 The seats shall be rigidly fixed to the test rig using the attachment points and supports foreseen by the seat manufacturer."

FIA Technical List 12:
http://argent.fia.co...roved_seats.pdf
(in which the type of support(s) is specified (i.e. lateral, bottom, and/or back), not a specific part number)

FIA Technical List 40:
http://argent.fia.co...anced_seats.pdf
(in which the specific support part numbers are specified for the listed seats)

Back to your regularly scheduled argument.

He cuts and paste a lot better than I do.

[Steve D]

See if this helps.

[Jim Boemler]

OK, so I will try to be clear. The picture above shows NEW METAL welded to the stock seat sliders. The seat in NOT attached to the stock sliders it is attached to that new contraption.

I cannot possibly tell you how many crappy seat installs I have seen.

Does your seat have built in bolt holes in EXACTLY the same place as the Mazda Miata Seat?

Yes it does. I drilled the bottom of the aluminum seat to match the rails. Does that make it OK, Mike? Please cite the paragraph, either way.

[KentCarter]

Yes it does. I drilled the bottom of the aluminum seat to match the rails. Does that make it OK, Mike? Please cite the paragraph, either way.

I think Mike's point is that once you have welded something on to the factory sliders they are no longer the factory runners and are legal. Mike, did I interpret your gobbledgook correctly?

[Jim Boemler]

I hope that isn't the "logic". Aside from being totally without any logic, such an interpretation would operate to allow much less safe constructions. Using my setup as an example, I would be precluded from using the stock, factory-tested mounting points, but I would be free to tack-weld some kind of garbage to the slider and put my life at risk! Such an interpretation would make a mockery of any real "safety" aspect of this rule.

[Keith Novak]

I'm not sold on that rule either. After all, the stock lap belt receptacle is attached to the seat so the sliders have to be designed to take some significant forces. On the other hand, forces don't go into the seat the same way with 3 point belts as they do a real racing harness in a sideways crash. Lots of apples and oranges there so it seems to me like they're trying to be on the conservative side. I know one inspector who told me he's even seen mounts made from wood so I can see why they'd be a bit conservative but the rule does still allow some pretty wimpy attachments.

[Mike Collins]

I think Mike's point is that once you have welded something on to the factory sliders they are no longer the factory runners and are legal. Mike, did I interpret your gobbledgook correctly?

Correct.

[Mike Collins]

Clown, you can get solid mounts that attach to stock seats mounts

[Jim Boemler]

I can get different mounts, but the question is whether they're required or not. The question also seems to be whether adding tabs to stock mounts makes them no longer stock mounts. It all seems pretty capricious, rather than backed up in writing.

[Mike Collins]

Fabricated by the seat manufacturer.

[Weekend Warrior]

See if this helps.

Did you create that Steve?

[KentCarter]

Jim, all rules about this stuff are somewhat capricious sounding. The rule for the back support is vague and almost untestable: how can you determine if the seat back support can withstand 200# of force? Especially laterally?

I think Meathead's interpretation is reasonable. The stock Miata sliders are fairly robust fore and aft. The heavy gauge steel locking fingers engage across multiple points, moreso than the Sparco even though that one is heavier steel. Cross bracing the slides from one side to the other should add a decent bit of strength, especially laterally and provide for a secure connection to an aluminum seat.

Like Meathead, i've seen some tortured attempts to mount a race seat to unmodified stock sliders, when a bit of welding would have made it strong and safe.

The FIA-style seats (mounting only at the bottom) present special challenges in my opinion. Once the seat-mounting humps on a Miata are removed from the pan, it's a really weak and flimsy place. With the upper torso being a major area of mass for a human body, the lever arm of the seat back pulling on the floor is tremendous. I'm not sure it can be made strong enough.

[Steve D]

Did you create that Steve?

Yes. I was trying to understand the rules and had to come up with a See Spot Run version I could understand. I have sliders in my Spec E30, hence my concern.

[Blake Thompson]

_{doesnt the seatbelt provide more restraint than the seat mounts anyway?}

[Jim Boemler]

Yes. I was trying to understand the rules and had to come up with a See Spot Run version I could understand. I have sliders in my Spec E30, hence my concern.

Exactly. What I can piece together so far (with regard to non-FIA seats) is that you can use any mount except the one designed for the car, and you can use that one as long as you add some homebrew stuff of some sort. Adding homebrew stuff makes it no longer the stock slider, and therefore acceptable.

None of this is actually written in the rules, but it appears to be the official interpretation.

[Keith Novak]

_{doesnt the seatbelt provide more restraint than the seat mounts anyway?}

Forward yes but not as much sideways, backwards, or down.

Jim- Simple solution for you...paint your seat mount. Everyone knows the stock ones are black. Then it's not stock but is just as strong.

[Jim Boemler]

Thanks Keith!