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Fixing Seats to floor, Stuart Taylor car
NS Dev - 17/3/05 at 01:09 PM

Still not sure what I am doing for seats, but if I go for GRP ones, what have people with thin alloy floors done to fix them in very low down?


ned - 17/3/05 at 01:27 PM

i've welded in a couple of 3/4" tubes across the floor to support the seats + frames. I believe mk use strips of approx 3-5mm steel plate.

I'm still toying with how to actually secure them, possibly rivnuts if they'll be strong enough.

Ned.


ned - 17/3/05 at 02:04 PM

Col,

Thanks, i had thought of putting two rivnuts in, one at each side and trying that, only prob would be making sure the threads were lined up. other pro with this method is that you start crushing the tube. better solution would be to weld in a bit of threaded tube, but i don't have facilities tto do this. rivnut seems easiest in the normal fashion.

the jury is still out though...

Ned.


DaveFJ - 17/3/05 at 02:36 PM

hav a look at how Paul G - aka 907 (used to be type 907) has done his, seems like a good solution to me....

he has used an alternative type of captive nut which has to be fitted from 'behind' but looks much stronger than a rivnut.

there doesn't seem to be a piccy in his archive - Paul would you care to elaborate on your solution ?

I may have a piccy of Pauls seat mounts at home somewhere - will have alook later


white130d - 17/3/05 at 02:46 PM

LR Defender seat runners are held to the aluminum (aluminium) seat box by rivnuts, something like an 8 mm


David


locoboy - 17/3/05 at 02:51 PM

A defender would be on its second barrel roll before you could exert even a quarter of the cornering force you can apply in a locost!


ned - 17/3/05 at 02:54 PM

but surely rattling around/fatigue wise a LR would have the same forces applied?


locoboy - 17/3/05 at 03:04 PM

If you can drive a Disco in the same fashion to replicate the forces you exert on the seat of your locost then im buying the beers at the next show!

there are pretty big twisting forces going into the GRP seats hence you see a lot of them are braced at the shoulders.

Dont forget that locosts vibrate a lot more than regular production cars too, so anything that can come loose ......................probably will!


NS Dev - 17/3/05 at 04:17 PM

All of this is good, but doesn't really help in that if I put a 25mm tube across the floor, the seat will be too high!

I could put 3/4mm strip across, weld to the box sections each side and bolt the seat through this and the alloy floor, would mr SVA be ok with this?

Somebody (think it was Ian Gray) mentioned just bolting the seat through the floor with very big washers, but with a 1.5mm ally floor, I think that would be pushing my luck!

If I end up doing expanding foam seats, I think I will just bung them onto the ally floor, but if I have a seat that concentrates the load into small areas, then I can't do this.


locoboy - 17/3/05 at 04:30 PM

Thats the method MK use and theirs pass no worries, i will be using that method also otherwise my seats will be too tall too.


907 - 17/3/05 at 04:44 PM

Hi All,

As DaveFJ said back a few posts, I used
8 mm hank bushes. To fit these you drill a half inch hole,
insert the bush, supporting the back of the bush,
and place a large ball bearing on the thin edge,
and "wack it wiv a big 'ammer".

As strong as a normal nut.

Pics now in my archive of how I used them.

Paul G Rescued attachment captive nut.jpg
Rescued attachment captive nut.jpg


locoboy - 17/3/05 at 04:54 PM

Kind of like a posh rivnut then.


Hank Bush..........................................................sounds like a redkneck president!


907 - 17/3/05 at 04:57 PM

Very posh... It's stainless


Volvorsport - 17/3/05 at 05:21 PM

the FIA spec seats we fitted indarrians didnt need upper bracing , they were stiff enough , im not really a fan of those thin GRP racing seats . we mounted ours on FIA spec subframes which if youve welded some tube or flat across the chassis you can bolt to those .

then if you do fall through, you get prior warning , before half your butt cheek gets wiped out .


planetester - 17/3/05 at 05:31 PM

Have a look at JAG photo archive under 2002, there is a sketch of a bracket he used to raise the seat belt height on an ST chassis, I dont know if he had it fitted for the SVA


indykid - 17/3/05 at 09:00 PM

quote:
Originally posted by colmaccoll
Ned could you drill ALL the way through your box section from above, Insert rivnut from BELOW and thread the bolts into the ruvnut from ABOVE, that means it will be trying to pull the rivnut against the flange that you normally see when you set the rivnut in the normall fashion.

I'm sure it will be harder to pull a rivnut out like this than if its set in the conventional way.

See below, apologies for the 'paint' sketch.



rivnut
rivnut


[Edited on 17/3/05 by colmaccoll]


if you use this method, when you nip the bolts up, it will un-set the rivnut, i.e pull it back out straight. surely if it is no longer tightened against the panel, it will no longer stay still, in relation to the tube, and will be free to undo.

tbh i think you'd be more likely to pull the threads out before the threaded section pulled through the crushed bit in normal wise.

just the whirring of the cogs in my head of course.
tom

do it like robin hood, stick a gurt bit of angle under the seats!


NS Dev - 18/3/05 at 08:43 AM

quote:
Originally posted by Volvorsport
the FIA spec seats we fitted indarrians didnt need upper bracing , they were stiff enough , im not really a fan of those thin GRP racing seats . we mounted ours on FIA spec subframes which if youve welded some tube or flat across the chassis you can bolt to those .

then if you do fall through, you get prior warning , before half your butt cheek gets wiped out .


I'm not a big fan of the GRP chell seats either, but due to me short in the leg and long in the body I need to sit a bit forward, and I am worried that what I would like to do (an expanding foam seat) won't work because the "gap" between my back and the backrest part of the chassis will be too big.

I thought about using a GRP seat to get the position right and then foam filling that to get the fit right (as some of those GRP jobbies have no support bits at all!!!)


ned - 18/3/05 at 10:23 AM

NS Dev,

grp seats are normally quite tight, would yo not be better off making a squarish oversize frame out of ally sheet to put the bag seat into? ( I presume you mean the polystyrene balls type bags which you use a vacuum + resin to set off/shape?

Ned.


NS Dev - 18/3/05 at 01:32 PM

Not quite, I was going for the wheelie bin liner and 2 part expanding liquid foam idea. put some in the bag, chuck it in the GRP seat and sit in it while it fills all the little gaps. They may be quite tight in some areas but not everywhere, which is what you want!

May well not work, but the foam is very cheap so worth a shot.

I hope not to need the shell anyway, but I worry that I will need the seat too far forward.