Foam Seat Kits

[Steve Brown]

One winter project of mine is to get one of those expanding foam seat kits from Demon Tweeks to make a more supportive seat for trackdays etc.

Any advice? Is it as simple as it seems in the catalogue?

[Mike Bees]

Do you mean the Indi-Seat kit? Or the 2-pack expanding foam DIY sort?

 

Mike

[tgracing]

I have no experience of either, but I think the Indi-seat is the more profeshnial product. The Safety Devices guy at the Autosport show reckoned a 'small' kit would be alright for a lardy like me in a 7. (Saftey Devices are the distributers and it's probably cheaper from them that DT. Places like Arrowstar will make one around you and they'll even cover in Alcantara, but that gets seriously expensive. Duct tape usually suffices).

 

I went for a covered foam pad in the end, since the cockpit fits me anyway. The 6pt harness keeps me in and a rib protection vest (read - bra) stops my ribs taking a pasting off the tunnel.

 

Davebo

C7 CAR

 

Edited by - davebo on 16 Nov 2000 17:24:26

[Steve Brown]

I was going to go for the cheapo 2 part expanding kit. Is it likely to be worth it?

[Mike Bees]

Plenty of people have made seats that way Steve. It probably does take a bit of trial and error, but it's cheap even if you cock it up and have to do another. I'm told it's much cheaper to buy the foam directly than from DT etc.

 

Here's some tips that were posted to the sevens mailing list earlier this week:

 

----------------------------------------

For this you just take a tough plastic bag (30 gallons worked

best for me) and pour the two-part foam mix into it. Close with

tape, put in the car and sit on it (it's warm and comfy).

Just a word of advice: put some very thin plastic painter

protection sheet all over your car including the footwell, and

wear old clothes and a shower hat. This foam is just a nightmare

to remove from the skin or the hair. Wear latex gloves during

the operation. The law of ever-increasing entropy fully applies

in these experiments...

 

foam butt recipe

----------------

- remove all seat and carpetting from your side of the cockpit

- leave the harness

- cover the cockpit with plastic sheet for protection (push it in the

footwell as far as you can as well)

- in a big container, pour an equal amount of part A and part B of

urethane foam. Usually that stuff expands by a factor 30 so work out

how much you want... In my experience the best is to use two clean

containers to measure about 3/4 liter of each part, then mix that in

a larger container (5 liters). You have about 30 seconds before it

starts foaming and expanding. Each part individually looks brown

(one dark, one clear). When you mix them thoroughly it becomes

creamy and starts frothing. That's the right time to pour the mix

in the bag (on the ground) and close it with duct tape.

- put the bag in the cockpit, working the sides so that it isn't all

wrinkled.

- you can put another sheet of plastic above the bag for further

protection

- sit on the bag, and make sure you can operate the clutch

- don't do the mistake I once did: camber your back "in order to get

better lumbar support in the future seat": this causes the muscles

adjacent to the spine to protrude, resulting in a ridge in the seat

just where the spine is. Very uncomfortable. Just relax in there.

 

The result is a hard foam seat that I found extremely comfortable and

that holds you in place really well. If I had the choice again, I

would buy my Caterham with the cheapest seats (or no seat at all) and

replace them with foam seats.

 

Now, the next step is to make a custom carbon fiber seat.

 

You can start with a foam seat, them sand the surface to remove

inegalities and make it look good. When you are happy with the shape,

then apply gelcoat and sand that to a smooth finish (220 grit, 400

grit, 600 grit, without skipping a step). Now wax it and apply PVA

release, then make a mold of it (fiberglass & resin). From this mold

you can make a carbon or kevlar/carbon seat by vacuum bagging.That's

something I want to do sometime but I recently ran short of time with

all the things to take care of with my move to Europe...

 

Personally, I think the all-foam approach is good enough. It's pretty

light, rigid enough. I raced with it and was pleased with how well I

was held in place. I was told it is easy to cover the seat with

headliner (the material used for trimming the cabin of trucks is very

compliant and can be shaped at will even on the compound curves of a

seat; the result looks really good). It's cheap enough to be remade

if necessary.

--------------------------------------

 

Another useful snippet:

 

I found a supplier, Glassplies (01704 540626) in Kitcar magazine

who sell this for approx. 5ukp/litre plus tax and carriage.

This means that 13ukp worth should be enough for a seat.

 

Mike

 

[Mike Bees]

And this is how not to do it:

 

----------------------------------------------------------

 

A friend of mine once built a canoe. He spent a long time on it and it was a work of art.

 

Almost the final phase was to fill both ends with polyureathane expanding foam.

 

He duly ordered the bits from Mr Glasplies (an excellent purveyor of all things fibreglass) and it arrived in two packs covered with appropriately dire warnings about expansion ratios and some very good notes on how to use it.

 

Unfortunately he had a degree, worse still two of them. One was in Chemistry, so the instructions got thrown away and the other in something mathematical because in a few minutes he was merrily calculating the volume of his craft to many decimal places and the guidelines got binned as well.

 

He propped the canoe up on one end, got a huge tin, carefully measured the calculated amounts of glop, mixed them and quickly poured the mixture in the end of the canoe (The two pack expands very rapidly).

 

I arrived as he was completing this and I looked in to see the end chamber over half full of something Cawdors Witches would have been proud of. Two thing occurred to me, one was the label which said in big letters "Caution - expansion ratio 50:1" (or something similar) and the other that the now empty tins said "approximately enough for 20 small craft."

 

Any comment was drowned out by a sea of yellow brown foam suddenly pouring out of the middle of the canoe and the end of the canoe bursting open. My friend screamed and leapt at his pride and joy which was knocked to the ground as he started trying to bale handfuls of this stuff out with his hands.

 

Knocking the craft over allowed the still liquid and not yet fully expanded foam to flow to the other end of the canoe where it expanded and shattered that end as well.

 

A few seconds later and we had a canoe with two exploded ends, a mountain of solid foam about 4ft high growing out of the middle, and a chemist firmly embedded up to his armpits in it.

 

At this stage he discovered the reaction was exothermic and his hands and arms were getting very hot indeed. Running about in small circles in a confined space while glued to the remains of a fairly large canoe proved ineffective so he resorted to screaming a bit instead.

 

Fortunately a Kukri was to hand so I attacked the foam around his hands with some enthusiasm. The process was hindered by the noise he was making and the fact he was trying to escape while still attached to the canoe.

 

Eventually I managed to hack out a lump of foam still including most of his arms and hands. Unfortunately my tears of laughter were not helping as they accelerated the foam setting.

 

Seeking medical help was obviously out of the question, the embarrassment of having to explain his occupation (Chief Research Chemist at a major petrochemical organisation) would simply never have been lived down. Several hours and much acrimony later we had removed sufficient foam (and much hair) to allow him to move again.

 

However he still looked something like a failed audition for Quasimodo with red burns on his arms and expanded blobs of foam sticking everywhere. My comment that the scalding simple made the hairs the foam was sticking to come out easier was not met with the enthusiasm I felt it deserved.

 

I forgot to add that in retrospect rather unwisely he had set out to do this deed in the hallway of his house (the only place he later explained with sufficient headroom for the canoe - achieved by poking it up the stairwell.

 

Having extricated him we now were faced with the problem of a canoe construction kit embedded in a still gurgling block of foam which was now irrevocably bonded to the hall and stairs carpet as well as several banister rails and quite a lot of wallpaper.

 

At this point his wife and her mother came back from shopping......

 

Oh yes - and he had been wearing the pullover Mum in law had knitted him for his birthday the week before.

 

----------------------------------------------------

 

Mike

 

[Glenn Wheeler]

Superb story Mike, it reminds me of a friend who used to race caterhams, in his quest to find the right driving position he decided to make his own seat using the bag method. In his rush to get on with it he made the mistake of not reading the ratio instructions, wearing his brand new levi 501s,fleece and timberland boots, and most importantly the bag thickness was determined by what was available, ie a corporation black bin liner!!.

All went well until the mix started to expand, so much so it lifted him out of cockpit and slowly sort of exploded everywhere as the bag gave way.

I can only imagine the puzzled look on the refuse collection mens faces when they emptied the remnants of his clothes etc from his bin.

[Anna Rexia]

And who wants a moulding of their own bum anyway - pervy teeth.gif

[mark.hall]

Thanks Anna, you've given me a great idea blush.gif

[Nick]

Mike - ROFLLAAB with a BWAHAHAHAHA as well!

teeth.gifteeth.gifteeth.gifteeth.gifteeth.gifteeth.gifteeth.gifteeth.gifteeth.gifteeth.gif

[Anna Rexia]

Ah, methinks a new line for regalia !! smile.gif

[Anna Rexia]

Where's the regalia bods then - why aren't they working on thisquestion.gifwink.gif (we even have a "roll" model - thanks Mark!)

[mark.hall]

Err..........Ahem........I think I should make my excuses and leave blush.gifbiggrin.gif