Another thought on home made seats

Brian · 05-16-07, 11:35 PM

Like Howard, I am short on dough with my build so I have also taken it upon myself to build my own seats.

Starting off with a pair of fiberglass shells from Bill Hough , I slightly widened the driver seat and used left over ali sheeting to make the back, sides and bottom which will be glued and riveted. Here are results so far. I still need to cut slots for belts, but you get the idea. Current thoughts are to inject expandable foam between the shell and ali to provide stiffen the structure. Covering will likely be nomex as my seat cover guy does a variety of work for the firemen up here. Seats are fixed mountings, but my pedals are adjustable in multiple positions fore and aft, left and right through a matrix of holes in the base plate. I'll post some pics later on after they are covered, and oh yes they are very comfy and should require very little in the way of foam padding.

Brian

Dalton · 05-16-07, 11:53 PM

Looking good, Brian. I am impressed with the way you guys can knock up a racing car with tin snips, rivets, and bits of scrap lying around the workshop. Really encouraging for guys like me who haven't got a 40 yet, or enough of the folding money.
Dalton

Howard Jones · 05-17-07, 12:12 AM

Hell YA!!!! We don't need no stinkin money!!!! It is amazing how comfortable these seats really are. The trick is to make them fit your body and not make them any bigger than you are. Anyway nicely done. Goes to show that these cars can be built for a lot less than you think if you are will to invest time instead of money.

Frank Catt · 05-17-07, 04:48 AM

Great stuff Brian, well done - you dont need any extra padding !

Malcolm · 05-17-07, 04:52 AM

Brian, can I scrap that peice of wood now, last used when you were over here?

My suggestion would be to foam fill the void, it weighs nothing but it really will stiffen up the structure. Suggestion is before you get these seats covered, make sure all indents and cut outs for the harness belts are made first. Look really good. I weighed my seats (GTD racing high sided jobs) and they were 15 kg each! These look just a fraction of that weight.

Brian · 05-17-07, 07:14 AM

Thanks for the kind comments guys, keeps the spirits up when I hit the road blocks.

Just weighed this configuration and one seat is a bit under 11 pounds. I am guessing that the foam fill, a layer of 1/2 padding and a nomex covering will add maybe 4 to 6 pounds, lets hope for 15 pounds and see what we get:-)

I REALLY want to keep this car light and with these seats, a lightweight chassis, no interior other than the ali cladding, no radio, no heat, no air conditioning, no brake booster, lightweight battery, small mufflers, etc I am anxious to see how low we can go..........

You can let go of the wood Malcolm.

Brian

Frank Catt · 05-17-07, 07:42 AM

Out of interest, my seats weigh just 6 kilo each

Brian · 05-17-07, 01:41 PM

Drills and sandpaper are going to have to be employed to hit Frank's benchmark for a light weight seat :-)

I'll fill em with helium if I have to............

Ron Earp · 05-17-07, 01:56 PM

Very very nice Brian, and gives me some ideas......

Is the fiberglass glued to the ally and if so what with?

R

Frank Catt · 05-17-07, 02:40 PM

Brian, the best way to make it lighter is to reduce what sits in it !!

Malcolm · 05-17-07, 05:15 PM

Meow!

Brian · 05-17-07, 07:16 PM

Ron, the shell is just taped on for now, but I am going to "glue" the unit together with a can of expanding foam that I'll pump into some holes. Then I'll just sand the stuff off that squishes out before covering.

Brian

David Morton · 05-17-07, 07:26 PM

Brian,
ever thought of 'growing' a seat to fit into your back shell which is to your personal contours and then having it upholstered with suede or some such? It's the same technology - two part foam with several stout dustbin liners to contain it while you deposit your form in it and let it go off . It takes about 1.5 hours to do it properly so you could sit there and play games on your notebook or read a paperback.

Chris_K · 05-20-07, 04:34 AM

David,

I've actually been thinking about this very same thing. I tried making a fiberglass seat and it was a little over my head for a first stab at things, but I have recently been thinking about lining the tub of my RCR as you suggest, arranging some sort of plastic bubble to fill with the foam and plopping my butt in it for an exact duplicate of my personal shape. If I used the correct foam, it wouldn't be much to arrange it in something like Brian has here to hold it in place.

Have you some recommendations regarding the selection of foam? I haven't researched too much into it yet (it's a bit down the list...) but I am keeping it in mind.

Russ Noble · 05-20-07, 04:46 AM

Chris, check out this thread for some info on certain foams.

http://www.gt40s.com/forum/gt40-tech...yurethane+foam

Cheers

Jac Mac · 05-20-07, 04:55 AM

I built the seat for my last race car using a method similar to the above, was one of the best seats I have ever sat in and fitted so tight that I confess to having completed more than one race without having worn the full harness belts fitted, only realised that when I went to remove them at race end.

I think I 'borrowed' the kids bean bag and laid up a layer of offcuts on a plastic sheet before doing the book reading exercise, then glassed the cured item into a light tube frame of same basic shape, hope thats how I did it , looks like I might need to do it again shortly.

Jac Mac

Frank Catt · 05-20-07, 05:10 AM

David, we tried making a foamed seat once for a single seater, plastic bags filled with two part foam, and then sit in it until it cured. Exept that the curing process creates a huge amount of heat, and the poor guy sitting in it nearly had his back fried until he could take it no longer and abandoned ship, we gave up on that idea then !

David Morton · 05-20-07, 05:46 AM

Well, I think the secret is to have an insulating material as a barrier between the victim and the bin liner and to keep the 2 part foam to a minimum ie the contours are roughed out before the foaming begins so the
foam then takes up the final bum (thats the butt in the USA) shape.
Once thats cured, you've got the final shape and then lay up a fibre glass
mould of your bum using this 'mould', let it cure and then lay up another fibre glass mould over but seperated from the shape of your bum which is now your final seat. The insulating barrier in the first step is the amount of padding you can include and your local trim shop can put a suede cover on it. Voila. One of the foams I've seen being used is the aerosol Mangers type which most D.I.Y. (Home-depot?) stock for about £8 to £10. I'll ask Hugh Absolem what he used for foam as I know he has 'grown' countless seats. In the lower echelons of M/Sport the teams just used tank tape after trimming off excess foam.

I/M from Hugh:
HAbsalom:The foam we used comes in either 1lt or 5lt can. There is a part a and a part b and you mix them together for about 2mins then pour in to a big bin liner bag and sit in it for about 15-20 mins. Then it should be set. You can buy it at Marsport in Reading.

RACEMET: thanks

So no particular specification there then.

In another phone call to Denis Davies, another racing man, he sounded a cautionary tale about a guy who foamed a crate containing a windshield (with plastic sheet to keep it from adhering obviously) and went home for the night. His workshop burned down. Additionally , Denis made a valid comment that the relaxed sitting position might not be the same as the driving postion and some adjustments may be necessary. Lastly, to avoid some of the heat issues, pre form some of the foam and let it cure and cool down , then use it boken up into small peices in the plastic bin liner. The latent heat during the 'sitting in ' process is commensurately lower.