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Author: Subject: Foam race seat - any tips before start ?
Andrzejsr

posted on 16/3/21 at 11:01 PM Reply With Quote
Foam race seat - any tips before start ?

Hello!

I am planning to make a foam racing seat for MNR Vortx. Was looking and rading at some tutorials on internet. Those are mostly relations from one time job.

Would like to ask here maybe some of You has experience with making such seat and could share some tips etc : which density foam is best (have seen from 30-200 grade which is from 30kg/m3 to 200kg / m3, the latter is described as stiff and has less expandability (the low density foam has huge expandability obot 20-30x , the high-density much less , something 1:5 .

Also - shoud the seat be with a plate on the bottom , so not directly sitting on the aluminium floor and steel bands to which original are the fiberglass normal seats mounted ? Was thinking to add some aluminum maybe 3-4mm plate bolted to those steel bands

Its is someone else picture but wanted to illustrate which steel bands I mean, its from Westfield but in MNR it is similar :

https://forum.wscc.co.uk/forum/uploads/monthly_2017_09/1.jpg.3b5b970605410b4b4ca0e3a19ba1ba1b.jpg

I am not sure that fitted with rivets floor panels have enough strenght to hold +/- 100kg driver in shaking car :-/

I will appreciate sharing any help, thoughts and tips in this subject !





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djtom

posted on 17/3/21 at 12:08 PM Reply With Quote
There's a good writeup in this thread that I've had bookmarked for years - still haven't got around to making one for myself though so I can't say how well it works in real life! Looks like they use a ply base to spread the load.

Foam Seats

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MikeR

posted on 17/3/21 at 10:18 PM Reply With Quote
Don't forget, the seat isn't holding you in, the seat belts hold you in. The seat stops you moving about. I think the foam seats will spread your weight over it's base, so you don't need the steel, just done velcro to hold it on place.

NB I made one 10 years ago and still haven't finished the car so I'm perhaps not the best person to advise

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Andrzejsr

posted on 18/3/21 at 11:28 PM Reply With Quote
Thank You djtom and MikeR.
The first link is very helpful , great tutorial !

The foam they use seems to be this one:

http://vi.vipr.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=362496020434&t=1579766422000&category=133209&seller=jjcraceandrally&a mp;excSoj=1&excTrk=1&lsite=3&ittenable=false&domain=ebay.co.uk&descgauge=1&cspheader=1&oneClk=2&secureDesc=0


Yes, I am aware that the belts are wht is holding me in place, but my concern is about the "bottom" . Maybe I will add two steel flat bars bolted perpendicular to the flat bars originaly made to bolt the sesat to. Those new bars will add surface and allow for proper positioning of the crotch straps to mount.
Well, still open to all ideas and tips !

As for the foam I have found two types which are described as to make race seat , one is 32kg/m3 , and second 43kg/m3 , expansibility in order 30 and 20x

https://www.ebay.co.uk/itm/2-Part-PU-Expanding-Foam-Seat-Kit-For-Motorsport-Racing-/362496020434
https://www.merlinmotorsport.co.uk/p/2-part-foam-seat-making-kit-ss-foam

So I need something in this range, maybe closer to this stiffer as Merlinmotorsport sells.





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Mr Whippy

posted on 19/3/21 at 06:57 AM Reply With Quote
Are the foams fire resistant? That would be my first question.
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Mr Whippy

posted on 19/3/21 at 07:01 AM Reply With Quote
quote:
Originally posted by MikeR
Don't forget, the seat isn't holding you in, the seat belts hold you in. The seat stops you moving about. I think the foam seats will spread your weight over it's base, so you don't need the steel, just done velcro to hold it on place.

NB I made one 10 years ago and still haven't finished the car so I'm perhaps not the best person to advise


The seats normally pushing back on the harness otherwise you'd be against the rear bulkhead. You definitely want the seat securely fixed to the car.

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JimSpencer

posted on 19/3/21 at 10:57 AM Reply With Quote
quote:
Originally posted by Mr Whippy
quote:
Originally posted by MikeR
Don't forget, the seat isn't holding you in, the seat belts hold you in. The seat stops you moving about. I think the foam seats will spread your weight over it's base, so you don't need the steel, just done velcro to hold it on place.

NB I made one 10 years ago and still haven't finished the car so I'm perhaps not the best person to advise


The seats normally pushing back on the harness otherwise you'd be against the rear bulkhead. You definitely want the seat securely fixed to the car.


Hi
Erm.. No..
That's not how a foam seat works, it completely fills the gap between your backside/back and the floor/bulkhead - Mike has it correct - it's standard practice to not fasten the foam seat in.
When swapping drivers you simply jump out, lift the seat out after you, drop your co-driver seat in, they hop in and do up their belts.

HTH

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Andrzejsr

posted on 19/3/21 at 12:24 PM Reply With Quote
As I understand it is not (fire resistant) , but that is also I think regular seats with soft foam or pads in everyday cars that goes on trackdays . All I can do is wear all in nomex and have instaleled Fire Extinguisher System. It is not easy flammable I think on the other hand.
I know there are FIA approved materials and it looks like expanded polyestrene small balls "glued" togeder in shape with special resin ? hardener ? . It behaves inf fire similar like regular polyestrene (I think, or maybe this is special one?)

https://www.youtube.com/watch?v=-1owY9cHT9o

As for the safety - above is good explanation how it improves safety in the case of impact.

As for the supporting I know it supports on the wall behind and on the floor. My only concern is the floor aluminium panel is riveted to the chasis.And I dont trust rivets a lot . Normal seat is sitting on the flat steel bars which are _welded_ to the chasis. So I would like the new foam seat supports also on those bars, not on the thin aluminium and alu rivets.

[Edited on 19/3/21 by Andrzejsr]





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pigeondave

posted on 19/3/21 at 04:59 PM Reply With Quote
I know its not foam but it shows how the seat is lifted out

https://youtu.be/yBjY5eH8rGo

and the fact that as stated above, the belts hold you in.

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Andrzejsr

posted on 3/5/21 at 01:36 PM Reply With Quote
Update - seat finished!

https://aswestfield.files.wordpress.com/2021/05/img_20210503_013505265.jpg?w=1024

https://aswestfield.wordpress.com/majsterkowanie/

All process was longer than I thought it will be. Used mostly 35kg/m3 density foam, with some 200kg/m3 at the bottom, total volume approx 10l of foam, 100m of duck tape, approx 0,5l resin and some fiberglass.
Fitting is great , cant wait to try it on the track , but it will take some time as I am still waiting some parts from MNR ordered last year... :-/

Thanks for all useful info and links!





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