Non-FIA Composite Seat Brace

[linc44]

Hi all,

So a friend of mine is considering hillclimb this season and I have been pushing him to get his act together to meet the rules. A question that came up is what to do about a seat back brace on a non-FIA composite seat (specifically a Corbeau FX1 Pro). Should a brace like the IO Port brace be bolted to the seat or just pushed up against it on a composite seat? We were under the impression that bolting the brace to the seat would reduce the strength of the seat back and provide an fixed "edge" that the seat might fold over in the event of a crash. On the flip side, IO Port's website says to bolt the brace to the seat no matter what material the seat is made of. Not to disregard the manufacturers instructions, but my personal opinion would be to attach a plate with much more surface area (say 12"x12" vice the 2.5"x8" of the current IO Port brace) and butt the seat up to it, thus removing the "edge" by spreading the load and keeping the original integrity of the seat by not drilling into it. What is the acceptable way to use a seat brace on a composite seat?

NOTE: I am aware that simply getting an FIA seat negates this entire issue, but he says that he found the FX1 to be the most comfortable seat for him and would like to make it work within the rules if at all possible.

Thanks!

-Lincoln

[sachilles]

I had that exact seat two years ago. It's pre-drilled for a seat back brace. I used one of the i/o port braces too.

[sachilles]

FYI, if he's using it in a subie, he may find that the front edge of the seat interferes with the transmission tunnel.

Other words of wisdom for that seat, the hole for the submarine belt is very small, so if the sub belt falls back through the hole, it's miserable to get it back up there. encourage him to do something to help keep the belt there. My wife sewed a piece of elastic on the cushion for me to retain the sub belt that worked well.

[linc44]

Thank you Seth!

[sachilles]

He'll also find that the seat flexes a little without a brace. The brace firmed it right up. Maybe if I didn't eat so many wings, and was a little trimmer, I might not have noticed the flex so much.
Winston has the seats now in his RX7, so he might be able to get a picture of the elastic sub belt retainer thingy.

[Mopar 151w2]

I would reccomend bonding a reinforcing plate to the composite shell, then bolting the brace to/through the plate . This prevents a weak spot at a bolt hole, and spreads out load, rather than creating a "hinge point".
Something like 1/8" aluminium or steel will work. Hillbilly method to bond to composite: Once a reasonably good mechanical fit is acheived, get your clamping figured out, and make sure your working and curing areas are VERY well ventilated. Use Loctite/Devcon "Plastic Welder" 2 part adhesive - it's the consumer version of "Plexis", the adhesive used to bond carbon fiber composite parts. It's bad nasty......
Solvent clean both parts before surface abrading (sanding) the areas to be bonded, on both parts. blow off the dust with clean compressed air. Mix the adhesive on a non-porus (i.e. metal) surface. Spread on both surfaces, fixture and clamp.

[walterclark]

I thought the hillbilly method involved "duck tape"...

I think bonding a large aluminum plate to the seat back and attaching the brace to that is an excellent approach. I thought of that as a way to brace a composite FIA seat in another thread but am not sure of the implications re: the FIA certification 8855-1999 so I didnt mention it. I havent yet done any research, beyond reading 8855 and 8862-2009, as to where the FIA draws the line between allowed and not allowed in regards to such things and the FIA certifications. I did find one caution against physically attaching a back brace in any way TO the seat itself - suggesting a brace and load distribution plate just be brought up against the seat back, but that would provide no lateral bracing. Of course the FIA cert issues dont apply to the seat in this thread. I did find some racing rules in the US (NASA and SCCA) that require FIA 8855 seats older than 5 years (except those that are part of a vehicle homologation) add a back brace. FIA vehicle homologation rules require 8855 seats be replaced at 5 years and 8862 after 10 years and nothing beyond what is in the homologation papers may be done to any part of the vehicle. That brings up the point that technically after 5 years a 8855 labeled seat is no longer 8855 approved, having expired, so any FIA limitation on attachments is moot beyond the obvious "dont do anything to make the seat unsafe". That expiration - and therefore no longer FIA certified - is probably where the NASA and SCCA rules regarding these older seats come from.

For my seat (Cobra Sebring Pro built to 8855), I happen to have had the main hoop installed just a couple inches behind the plane of the seat back. The original harness bar (for my older Sparco seat) and the new harness bar (higher for the new seat and recommended Hans harness positioning) are in that plane. They would limit the movement of the seat rearward beyond a couple inches of flex and are located in the upper back and shoulder region where the greatest force to the seat back would be in a rear end collision. This seat is Carbon/Kevlar construction with head and upper body lateral restraints but it is not certified to the much more rigorous 8862-2009 standard. You may recognize an 8862 seat by the price tag - usually over $3000.

[Chief Geek]

Newbie question.

What event/sanctioning body/class requires a $3000 seat?

Paul

[walterclark]

I am not aware of any in the US that require 8862-2009 seats as of now. They ARE much stronger than seats that just make it past 8855-1999 standards so they are a good idea if one can afford them. There are 8855-1999 seats in production that approach the 8862 standard, but they also approach those seats in terms of price.

Then there are very strong seats that do not have any FIA certification. Custom race seats that sell only in the US are often in this category.

[Chief Geek]

Whew. I was afraid you were going to say 8862 seats were required for Mt. Washington or some other event that I hope to compete in, some day.

I think most all of us would agree that quality, high-specification safety gear is cheap insurance. I was just worried that the "insurance" would cost too much more than the vehicle it bolts to.

Is there a specification that defines the aluminum, the popular-in-NEHA, Kirkey-style (sp?) seats are built to? They look perfectly reasonable for our level of "club racing" but I'm sure there's a reason ALMS cars don't use them.

Paul