sjmmarsh Posted December 13, 2003 Share Posted December 13, 2003 At 6'4", I am looking to build a foam seat in order to get sufficient clearance between the top of my helmet and the roll bar. I have read the FAQ and now have all the parts I need to proceed: 1 large sheet of plastic to protect the car 1 Strong plastic bag to put the foam in 1 seat bottom from Oxted trimming 2l of 2 part foam. Before I take the plunge and mix the foam up, I'd appreciate some advice: 1) The archives talk about two methods of making the seat; you can either put the seat bottom in the bag with the foam, or keep it outside the bag. Is there a preferred way to do this? I can see that putting it in the bag will result in a stronger bond as the foam will stick strongly; the downside is you only get one shot at this . (Can you dremel it out once it has set?) 2) If I put it in the bag, is there a way of keeping the foam off the bottom of the seat? (vaseline? cling film?) 3) what volume of mixture should I be aiming for? It looks like I don't need much padding round the sides as I can only just get my fingers in between my hips and the sides of the cockpit (it is an SV as well. 😳) - but there is a gap between the small of my back and the seat that is quite large as I am not sitting upright in the seat - my height is more in my back than my legs. Those are my main questions, but I'd appreciate any practical tips from anyone else who has done it for real! Steve Link to comment Share on other sites More sharing options...
Rob Walker Posted December 13, 2003 Share Posted December 13, 2003 Put the base in the bag, the foam will not go under the base, even if it does you can sand it away with coarse sand paper. I would always mix small amounts as you can always add more if needed and would start off with a max of 1/4 pint of each component for something as small as a seat base. Temperature is also critical if you want good expansion ideally 15C plus. Link to comment Share on other sites More sharing options...
BigYin Posted December 13, 2003 Share Posted December 13, 2003 Steve Being 6'2" and a bit, 18st (though it sounds like you may not be as lardy as me), and with an SV, my experience may be relevant. I kept the standard seat back (mainly for the head restraint) and the fore and aft adjustment of the standard runners, but wanted to get my backside closer to the floor, improve under-thigh support as well as getting better location. So I made a foam base only. This fits around the bent wire seat frame, so doesn't need an OTC seat base (in fact if you use an OTC seat base you'll still be sitting above the seat frame, rather than in it, and won't be much lower in the car). I'd add to your recipe 2 x "rubble grade" bin bags (B&Q do excellent ones), 1x cheap plastic bucket (99p again from B&Q), a clean stick, some gaffer tape and if you want to be really fancy some bits of strong cardboard sheet (or softwood), a transistor radio. First, position the seat where you normally sit (right back I guess), remove the seat squab and tape pieces of card on the central tunnel and side panel to give a bit of clearance between your new seat base and the sides. Next, cut the bottom off one of your sacks and tape the 2 sacks together (inside and out) to make a long, strong tube that will go right up your back to just below your shoulders. Test fit the sack in the car to see how far down the seat well you want the seat to go and if necessary tape more card between the tunnel and side panel to make a sort of dam across the seat well that will provide a forward limit for the new base. Remove the sack from the car. Now you're ready to start cooking and you may find a sympathetic assistant to be of great benefit from this point. Go to the toilet. Put on your Marigolds and cover the cockpit with thin plastic if you're nervous. (Mrs BY suggests using any spare gaffer tape to seal the talking aparatus of the sympathetic assistant to stop them laughing). Mix the 2 pack kit in the bucket (you might as well use the whole 1kg kit), stir briskly with the stick and within about 10 seconds the mix will go milky . IMMEDIATELY pour the mix into your long, strong sack which is being held by your sympathetic assistant. As soon as the mix starts to expand (this only takes a few seconds so work quickly) put the sack in the car pushingit well down and around the seat frame. Sit in the car, quickly but gently so that you let surplus foam go up the long, strong tube rather than bursting the sealed end (very nasty and guaranteed to put an end to cordial and constructive relations with the sympathetic assistant). Settle yourself gently onto the foam filled sack trying not to adopt a distorted posture especially with your back - and relax. The foam will get quite hot. If you're wearing resonably thick trousers and top this won't be a problem (although you will thank me for sending you to the toilet before you started). In fact, I find that it does my lumbago a power of good and is better than a trip to the physio. Get sympathetic assistant to switch on tranny and bring mug of tea. Sit STILL, listen to tranny and enjoy tea for about 15-20 mins by which time the foam should be nicely set. Extract yourself gently from the car, remove gaffer tape from assistant and thank them for their invaluable help. After suitable interval remove sack from car and use a Stanley knife to help you peel it off your beautiful new seat. You should now have a anatomically perfect seat base that also goes part way up your back to give just the lumbar support that you need. All that remains now is to trim away the surplus foam (Buzz saw, Stanley knife), cut slot for 6 point harness, if you use one, sand any rough bits, and cover your masterpice in yet more colour coordinated gaffer tape. You can now show the finished article off to neighbours, family, friends and even innocent passers by all of whom will be astounded by your skill. Good Luck and Good Foaming. Silver SV SSR Link to comment Share on other sites More sharing options...
Jason Plato Posted December 13, 2003 Share Posted December 13, 2003 Personally - having moulded quite a few seats for different people , I would *not* use bigyins method, it sounds like a recipe for disaster This stuff sticks to everything , you need to do it in a controlled manner . Go with Robs method , use some plastic 2 l coke bottles cut in half and then weigh out equal quantities of gooe ,use 2 std bin liners - one inside the other , the bags should be the wheelie bin liners - the realy long ones . I would go with 0.5Kg of each part and then add some more and more until it fits you perfectly . After each bit is poured you only need to sit perfectly still for about 5-7 minutes . If you are not happy with the fit , then make another mix in a coke bottle and add , if you are carefull you shouldnt even need a new bag . I would also put the seat base inside the bag , and insluate the floor with some of that very thin material that new electrical equipment comes wrapped in , this will aid the expansion . The reaction of the 2 parts is exothermic , but it is no hotter than sitting in the bath , dont fret about this bit . Dave Lotus 7 Club Speed Champion 2003 South Wales Area Organiser C7 TOP Edited by - Dave Jackson on 13 Dec 2003 19:00:07 Link to comment Share on other sites More sharing options...
Slipper man Posted December 13, 2003 Share Posted December 13, 2003 I would concur with Dave and ROb, except that I cannot see the point in dirtying the base. I put the foam pack on top and had Oxted trim the result. Looks good, works great. I also kepth the standard back and runners so if someone wants to use the standard base, it can be swapped in seconds. Link to comment Share on other sites More sharing options...
Jan T Posted December 14, 2003 Share Posted December 14, 2003 Is BigYin wrong to suggest that the use of a seat base does not acheive a lower seating position? Jan Link to comment Share on other sites More sharing options...
Nifty Posted December 14, 2003 Share Posted December 14, 2003 Give Marc Hicks of Anglia Sevens a ring on 07814 477964. He should be with me from 10.30am onwards and therefore available. He's made a few bespoke foam seats for well known figures, including one M. Shoemaker. Keep off the straight and narrow 😬 (Edited because I seemed to spell like a Yank 😳) Edited by - Nifty on 14 Dec 2003 00:37:26 Link to comment Share on other sites More sharing options...
Jason Plato Posted December 14, 2003 Share Posted December 14, 2003 Jan , the seat base will still be in contact with the ally floor panels - as with a standard seat , the height at which you sit all depends how much foam you put under your bum . Lotus 7 Club Speed Champion 2003 South Wales Area Organiser C7 TOP Link to comment Share on other sites More sharing options...
BigYin Posted December 14, 2003 Share Posted December 14, 2003 Chacun a son gout! Silver SV SSR Link to comment Share on other sites More sharing options...
Nifty Posted December 14, 2003 Share Posted December 14, 2003 Mais oui Keep off the straight and narrow 😬 Link to comment Share on other sites More sharing options...
sjmmarsh Posted December 25, 2003 Author Share Posted December 25, 2003 Getting close to making the seat now (while the weather is milder as I have to do it in the garage). Re-reading the advice it struck me that there are two ways of making the seat - with and without the existing S-type back. I intend to keep the back and just mould the seat squab - what volume should I be aiming for? 1/2 litre of each mix may be a bit OTT, so I will try a smaller amount first. Also, does the plastic bag peel off easily from the foam once it has set? Steve Link to comment Share on other sites More sharing options...
Slipper man Posted December 26, 2003 Share Posted December 26, 2003 If you are keeping the seat back, then use 1/3rd of the tins and keep the seat base out of the bag. the foam stick like araldite, and you will not be able to seperate anything from it when set. Cover the seat either with duct tape, or do what i did and get Oxted to trim it - really looks good. Link to comment Share on other sites More sharing options...
Jason Plato Posted December 26, 2003 Share Posted December 26, 2003 In an earlier post I suggested 0.5Kg *not* .5L . The bag peels off easily . Lotus 7 Club Speed Champion 2003 South Wales Area Organiser C7 TOP Link to comment Share on other sites More sharing options...
Asklepios Posted December 26, 2003 Share Posted December 26, 2003 My experience was that the cheap and nasty bin liner became incalcated in the mix. Dave , what does a litre weigh , if not very close to one kilo ? Link to comment Share on other sites More sharing options...
Jason Plato Posted December 26, 2003 Share Posted December 26, 2003 This stuff is heavier than water , the 2 parts are also different densities , so if you simply weigh out then you will use 30% LESS of part B than Part A . The bag peels off easily *if* you use a decent bag ........ just get on with it ! Lotus 7 Club Speed Champion 2003 South Wales Area Organiser C7 TOP Link to comment Share on other sites More sharing options...
sjmmarsh Posted December 26, 2003 Author Share Posted December 26, 2003 I made the seat today - thanks to all your advice. In the end I used 500g of each mix, which turned out to be too much (it foamed above my shoulders) although as I had used a survival bag (2m long) this wasn't a problem. It was also easy to peel off, except where it had wrinkled and buried itself at the front corners. I had to mix another 100g as there were still a few hollows - I must have sat on the bag too soon. The top up was easier to do and I am pleased with the finished seat, although the silver duct tape I used doesn't look right - I will look for some black tape if the seat works out OK. I have photos of my attempt, so will put them up on the web when I get time. Steve Link to comment Share on other sites More sharing options...
Jan T Posted December 27, 2003 Share Posted December 27, 2003 Steve Glad to hear you are out blatting and enjoying it ....I am very jealous of the roads you have on your doorstep. About the seat did you end up making just a base or a back as well? Also when I made my first one there was no way the bag was going to part company with the foam ....it was pretty well 'integrated'. Did you also use a plastic seat base and if so outside the bag? Got any trackday plans for next year now you have the seat? Cheers Jan PS just off for a blat to test my wife's new hat PPS she's wearing it, of course 😬 Link to comment Share on other sites More sharing options...
sjmmarsh Posted December 27, 2003 Author Share Posted December 27, 2003 Jan Yes, the roads round here are very good for blats. I just made up a seat base, and am still using the S-Type back. I masked off the cockpit with cardboard and binbags (it wan't needed). I put the base in the bag with the underside masked off with a taped on bin liner. Reading the archives, it seems you can do it either way, but I thought that putting it inside would result in a stronger seat base and I could always dremel it off if I needed another go. I used a £2.99 survival bag from Millets as the foam bag. It is strong, so unlikely to burst and at 2m long, it is unlikely to overflow (the foam did come up my back quite a way and foamed over my shoulders as I am pretty wide, so the only place the foam can go is up). The bag is strong, so pealed off easily except where it was embedded. It struck me as a good bag to use if I had wanted a complete seat making. I haven't had time to try the seat out yet. Loads more head clearance, but I am lying down in the car more, with my knees nearer the wheel. Steve Link to comment Share on other sites More sharing options...
BigYin Posted December 27, 2003 Share Posted December 27, 2003 Steve Glad to hear that what sounds like a modified BY technique worked for you (Oh ye of little faith!). I've now taken B&Q off my approved suppliers list and added Millets based on your experience. BTW did you have to use a lot of gaffer tape on the sympathetic assistant or did you manage the whole process single handed? Happy lower CoG blatting in '04. Silver SV SSR Link to comment Share on other sites More sharing options...
sjmmarsh Posted December 27, 2003 Author Share Posted December 27, 2003 Thanks BigYin I didn't need gaffer tape - the only help I needed was making sure that any surplus foam didn't spill out the top of the bag. It went over my shoulders, but as the bag reached the top of the roll bar that wasn't a problem. Steve Link to comment Share on other sites More sharing options...
sjmmarsh Posted December 28, 2003 Author Share Posted December 28, 2003 I have put the results of my experience of building a foam seat up on a web page (not pretty as it is my first attempt, but it is functional) here Let me know what you think! Steve Link to comment Share on other sites More sharing options...
Jason Plato Posted December 29, 2003 Share Posted December 29, 2003 That seat base occupies a lot of the space under your bum by the looks of it . Is the seat base realy needed?? or , could you have simply laid a piece of card over the seat rails and then poured the foam mould on this and save £20 , and made a base with a little more shape to it under your 🙆🏻 and up the sides of your thighs . With the volume of foam you have moulded I can appreciate why you only require 300ml of gooe . Dave Lotus 7 Club Speed Champion 2003 South Wales Area Organiser C7 TOP Link to comment Share on other sites More sharing options...
sjmmarsh Posted December 29, 2003 Author Share Posted December 29, 2003 Dave To get my head lower I am almost lying down in the car, so my buttocks are now resting on the front bar of the seat frame. The wedge of foam you can see towards the rear of the base actually supports my back (lumbar region). I used the Oxted seat base because there is only about 1-2mm of foam in the centre of the seat base, which wouldn't have been enough provide the necessary strength to hold the base together. There actually isn't that much room at the side of my legs or body either (I am 6'4" and 115kg) which is why I needed so much vertical expansion room - the only place the foam could go was upwards or to burst the bag, hence all the masking. I may give it another go if I need to redo the seat, using your method. Steve Link to comment Share on other sites More sharing options...
Jason Plato Posted December 29, 2003 Share Posted December 29, 2003 6'4" & 115Kg in a 7 bloody hell - have you considered a getting a taller fia bar made up ? , I'm sure if you approached a company such as Rollcenter or safety devices , they may be able to help you out ? Lotus 7 Club Speed Champion 2003 South Wales Area Organiser C7 TOP Link to comment Share on other sites More sharing options...
BigYin Posted December 30, 2003 Share Posted December 30, 2003 Steve Just had a look at your website. Fantastic! I began to get quite nosatalgic about those hot, mid-summer days pouring my own foam. The cardboard lining of the cockpit looks particularly impressive - far move comprehensive than my own somewhat Scandinavian minimalist efforts. If I might say so, looking at your finished seat your a*se must be even bigger than mine (Mrs BY, who is a biologist of some renown, has just interupted me to point out that this is anatomically impossible and that it must just be that you are actually sylphlike but like an "easy" fitting seat). Jan's posting, however, reminded me just how good the roads are in your 'hood. I've had a few great mid week runs from mid-Staffs to Suffolk by the direct route (Ashby, Coleorton, Belton, Rempstone,Wymeswold, Asfordby, Melton, Oakham, Empingham, Stamford etc), but always in an M3 rather than a 7. So, I've now promised myself that the first fine, non-working, unsalted day that I find myself less than fully occupied I shall blat over your way just for fun. What's the latest Gatso situation over there? Silver SV SSR Link to comment Share on other sites More sharing options...
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