Seat Fixings

[s2xr2]

I am hoping to start motorsport this year with some hillclimbs/sprints and therefore preparing my car. My question is:

What is the best (safest?) way to fix a bottom fixing seat to the car shell?

I need to keep it all FIA approved and wondered what method is best. I have been suggested a few:

1) Use the original or substitute runners (but neither quite match exactly and will need hacking, is it an FIA approved method)
2) Fix it to the shell and bolt through the floor (but is this really safe in a crash, also does the bolt holes need reinforcing with sheet metal)
3) Weld in two metal box section runners between the sill and centre tunnel, then bolt seat to these (any comments on thickness and section size e.g. 20mm x 10mm x 3mm)
4) Fix it to the Roll Cage

Any help would be appreciated.

S2

[racingdad]

get someone who knows what he is doing to help you!

[JimW]

Welcome to Ten Tenths.

I am sure that most of the methods you are contemplating could be made to give a satisfactory result. Bear in mind that fixing the seat well is every bit as important as fixing the seat belts for your safety if something goes wrong. Racingdad's advice is good.

To find some more advice if you post where you are intending to climb/sprint it might be possible to identify a scrutineer in your area who could be approached for some advice. (I guess that it might cost you a pint )

Additionally say what sort of car and seat and you might find that someone has already addressed that combination. Ask the seat manufacturer/supplier.

Good luck.

Jim

[johnw]

Hi s2xr2
I haven't seen a bottom fixing seat for years. What make /model is it? Also what car is it going into and what type of cage will you be fitting. I assume that the seat will be fixed, as adjustable runners are not a great idea.

If you let me know where you are based, I'll point you in the direction of one of our competitors who will be happy to help you out.

As Jim says, correct seat installation is vital to your safety, so don't mess about. The blue book gives only minimum requirements, and it is possible to do considerably better. Any mounting to the floor will need reinforcement, not just the bolt holes, but the area surrounding them. The floor is only thin tin and can easily tear in a severe shunt.

John

[s2xr2]

Thanks for the welcome.

The car is a MK2 Fiesta XR2 (cheap and easy to get started), the seat is Corbeau Forza Sport (cheap FIA approved), I'll probably use a Safety Devices cage. I am targetting safety first more than anything so everything else will be standard.

I will be joining BARC SW (Gurston Down as my club and region), they have already helped me lots with the basics when I attended a training day.

Any contacts would be great, knowing the right people I am sure is best option.

Thanks, S2

[johnw]

s2xr2 you are welcome.
If you haven't yet had the cage fitted, you can ask SD to supply seat mounting bars to weld between the sill and central tunnel.
Alternatively call Custom Cages (R&D Motorsport) in the Coventry area. (Let me know if you can't find them)
These guys sell weld in cages or will build them in for you and can link the seat mounts to the cage. Highly recommend them as their cages have saved me twice in big shunts.
All the best
John

[THR]

id have thought that bolting it to the bottom of the shell would be enough, and perhaps use M8 bolts, with big 80mm washers (probs have to make these) 1.5mm thick. the bolts will not shear, and the area of the washe will make the floor rip before the seat came adrift.
how big are the holes in the seat fixings? 9mm holes would be m8, 11/11.5 would be m10 etc. take a guess.
if your using it for a hillclimb, then they are a bit more freindly that a circuit marshall! but not that much lol.

how is the orginal car seat fastened? id have thought that upping the size of the bolts and washers once would be enough.

interesting question tho, cos it seems quite basic, but aint really !! lol

[Onlooker]

Attaching it to the sill and tunnel,via a roll cage attached seat frame is the best.1/1/4 tube with threaded inserts welded in are a great way of attaching the seat using the side plates that came with most seats.This has the added advantage of being part of the cage and not part of the floor pan. Bolting it to a bit of 0.9mm sheet metal is suspect regardless of the washer size,in the event of a big hit you will either distort it badly or may just tear it out altogether.By attaching you belts to this same frame work you,the seat and the roll cage are one.I have seen a few drivers whack there melons on the pillars whilst remaining securly fastened to a seat that has bent the floor enough to allow the belts to come with it or loosen signicantly.

[zefarelly]

are you allowed to weld the shell up like that though? for historic saloons your not allowed to weld the cage in, it must be bolted, therefore you cant weld tubed accross the shell, and thereby strengthening / modifying it ???

[Onlooker]

Fair point,I was not aware of that.I don't see to many bolted in cages much anymore,so assumed it was welded.You could still weld the bars to the lower hoop bar and then to a bar that was weled to the bottom door bar and bolt it to the trans tunnel.
Welded cages are probally something that should/will get mandated soon anyway.