vfiend Posted January 4, 2013 Report Share Posted January 4, 2013 I've been working myself upto this for years... Before I even had a 'big' bike I remember reading the Dale Lomas Cannonball Run article in PB, To further the distance an extra underseat aluminium fueltank was fitted - what a novel idea I've thought since. Why is the fueltank fitted onto of the already heavy engine? all that fuel sloshing about so high. I appreciate it's a convenient way to balance weight between a front rear bias offsetting rider weight to the rear; but with mass centralisation weight should be low - not to mention all that pressed sheet steel, heavy even when empty. I have to shift weight back on fast corners anyway, so it may balance my current steed a little too. Obviously as many of you are aware newer bikes have started moving them back and low, the CBR's with plastic tank covers being a good example. It's something I pushed to the back of my mind, until I started thinking about what I could do to improve my racebike. The steel subframe weighs a ton, why not make an aluminium one, while I'm at it; why not put a fuel cell in the subframe and move the electrics forward?.. Then reading PB, they'd done it to the PB racing trumpet! It's an inline4 which makes the packaging easier than my v4, but there is still ample room to fit enough fuel for a 10 lap race. Fuck it, I'm on it. In the shed now sits a cbr plastic tank cover, some aluminium and a TIG welder. I'm moving the tank back and low, this will be made to fit within the subframe. Before I start this I will need some advice and inspriation, so all-mighty knowledgeable PBMagForumites, I need your help - Anyone done this? What should I watch out for? Longterm what flavour ally shall I opt for? What is the ideal thickness - 2mm seems a little thick, so 1 or 1.5? Would it be overly brave to go thinner? (although going so thin may exceed my ability) My plan is to rubber mount the tank to the subframe, that will hopefully reduce some heat transfer and vibration. I'll bend as much as possible into shape from a large sheet around a form before I get to welding and ad further strengthening bends and ribs where it seems appropriate. I'll add somekind of level viewing system and some cellular anti-slosh stuff for stability. I'm also thinking of maybe getting the tank carbon wrapped after which should offer some further piece of mind and stability - although it'd be more difficult to spot any crack propagation... What else should I consider? Any advice much appreciated and if you enjoy other's misery stay tuned to this thread as it will inevitably end in a giant ball of flames at Donington in April - the first race shakedown and my final final deadline. Link to comment Share on other sites More sharing options...
Superdunc Posted January 4, 2013 Report Share Posted January 4, 2013 NS4 Aluminium in 1.5 mm will be fine. MDF is good for formers. Try and design it so any welded joints are lap joints rathe than but welds, will make your life much easier. if you need to buy any weld on fittings, buy them from A/h fabrications (Kannerdog1x1's employer) the others you see advertised as weldable.. aren't. Something like this As per BS308 the welds are red ! The flanges only need to be 10mm, but they stiffen up the panels and help prevent them distorting during welding Link to comment Share on other sites More sharing options...
vfiend Posted January 4, 2013 Author Report Share Posted January 4, 2013 Is the tank under the seat going to be supporting the weight of the seat and rider? Hell no. I design tooling/fixturing, and thats only a small part of the day job (it's certainly not something I'd call a regular thing), everything I do features a large factor of safety to withstand abuse, although I've a good working appreciation of the fancier side of my work's business (I have to regularly work with the designers, stress, thermals etc); I wouldn't dare take on something so sophisticated as you've mentioned as a home DIY project that I intend to sit on at 160mph. (I wish I had the confidence to attempt what you suggest and the thought had crossed my mind, but I'll keep it simple this time.) The tank will be sitting within an over-engineered box section subframe, This should hopefully afford some additional crash protection for small mistakes... Link to comment Share on other sites More sharing options...
marcaztls Posted January 5, 2013 Report Share Posted January 5, 2013 Just about to respond to your pm, and I do indeed wish you the best of luck and will be following this with interest. Link to comment Share on other sites More sharing options...
vfiend Posted January 5, 2013 Author Report Share Posted January 5, 2013 Something like this As per BS308 the welds are red ! The flanges only need to be 10mm, but they stiffen up the panels and help prevent them distorting during welding ^^^ top edit sir The suggested construction would also make more efficient use of sheet than I had been thinking Cheers for the reply marcatztles, top thought about diverting fuel to the pickup so every last drop is used, - I'll create some kind of well probably, also getting it pressure tested may well be a worthwhile idea - better than just giving it a good shakedown up the local back lanes. Link to comment Share on other sites More sharing options...
Superdunc Posted January 5, 2013 Report Share Posted January 5, 2013 Definatly pressure test it, it's very easy to get tiny pin hole in alloy welding, and where petrol molecules are so small they will find any holes. Use some bits of rubber pipe, jubilee clips and a tyre valve. Put 10psi in it and drop it in the bath, any small bubbles are leaks, large bubbles are you breaking wind. Link to comment Share on other sites More sharing options...
kanerdog1x1 Posted January 5, 2013 Report Share Posted January 5, 2013 This^^^, but I'd be wary of 10 psi. More like 2-3 psi for a fuel tank, otherwise it'll balloon like a football and you will be in tears. Link to comment Share on other sites More sharing options...
kanerdog1x1 Posted January 5, 2013 Report Share Posted January 5, 2013 To add, we have all the fittings you could ever need at work, an/dash/jic, bsp, npt, and push on fittings in whatever size you could think of, with the all important 'barb'. Also we have some new screw caps that are dying to be fitted to a mo'bike, anodised black cap and slightly bigger than normal. Link to comment Share on other sites More sharing options...
garage19 Posted January 5, 2013 Report Share Posted January 5, 2013 Pics of the caps please. I seem to keep using those £15 1.5 inch diameter ones all the time. Link to comment Share on other sites More sharing options...
garage19 Posted January 5, 2013 Report Share Posted January 5, 2013 If you don't want to out it in the bath just put some soapy water in a squirts bottle and squirt all the seems. Link to comment Share on other sites More sharing options...
Evilchicken0 Posted January 6, 2013 Report Share Posted January 6, 2013 Could you use the subframe and put cut sheets onto it. You could just do bottom and sides with a bladder inside it. Link to comment Share on other sites More sharing options...
vfiend Posted January 6, 2013 Author Report Share Posted January 6, 2013 This^^^, but I'd be wary of 10 psi. More like 2-3 psi for a fuel tank, otherwise it'll balloon like a football and you will be in tears. I was wondering if it was a little much, I would cry lots. To add, we have all the fittings you could ever need at work, an/dash/jic, bsp, npt, and push on fittings in whatever size you could think of, with the all important 'barb'. Also we have some new screw caps that are dying to be fitted to a mo'bike, anodised black cap and slightly bigger than normal. I'll be in touch when I figure out what I actually need, I'm currently a little clueless. Could you use the subframe and put cut sheets onto it. You could just do bottom and sides with a bladder inside it. I'd considered sheeting the subframe to use as a tank, but dismissed it as a bad idea. A bladder is a new idea to me entirely, although I doubt it'd be acu compliant... I'd likely worry about it splitting, same reason I ruled out using a plastic tank. Link to comment Share on other sites More sharing options...
Toneale Posted January 6, 2013 Report Share Posted January 6, 2013 These work and can be made to any size/shape you want. http://www.atlltd.com/racebike/racebikeproducts.php Farking expensive though just ask Kannerdog how much his quick dump filler was! I inquired about getting one made to put under a carbon cover the cost was around £1500 plus an addition tooling charge of about £200. Link to comment Share on other sites More sharing options...
vfiend Posted January 7, 2013 Author Report Share Posted January 7, 2013 These work and can be made to any size/shape you want. http://www.atlltd.com/racebike/racebikeproducts.php Farking expensive though just ask Kannerdog how much his quick dump filler was! I inquired about getting one made to put under a carbon cover the cost was around £1500 plus an addition tooling charge of about £200. Definately won't be doing one of those then. I'll stick with the idea I've got, thin sheet tank nestled within a subframe. It's far from simple (that'd be using the original tank), but is hopefully simple enough, I'm hoping it looks quite pukka too, cheekily poking out under the seat Link to comment Share on other sites More sharing options...
kanerdog1x1 Posted January 7, 2013 Report Share Posted January 7, 2013 Shit, I meant to grab a pic of the fillers we have. Sorry, I will get some pics tomorrow. Link to comment Share on other sites More sharing options...
Conica Posted January 8, 2013 Report Share Posted January 8, 2013 I wouldn't mind a nose at some Piccies of them myself bud Link to comment Share on other sites More sharing options...
Farmfab01 Posted January 8, 2013 Report Share Posted January 8, 2013 This is something I hope at some point to have a go at myself in the future, I remember reading in PB that the chap who made the tank for the PB 955 project had problems with the tank warping with the heat where the fuel pump was mounted. I don’t know how they over came the problem but it is something to bear in mind, does yours have a pump to go inside? Link to comment Share on other sites More sharing options...
marcaztls Posted January 8, 2013 Report Share Posted January 8, 2013 A new pump mounting flange was made, thicker, that took the heat better. Link to comment Share on other sites More sharing options...
vfiend Posted January 8, 2013 Author Report Share Posted January 8, 2013 This is something I hope at some point to have a go at myself in the future, I remember reading in PB that the chap who made the tank for the PB 955 project had problems with the tank warping with the heat where the fuel pump was mounted. I don’t know how they over came the problem but it is something to bear in mind, does yours have a pump to go inside? There will be a remote low pressure fuel pump as the bike is carbed not injected, so just an outlet, no fuel pump manifolds to seal fortunately Good to see I'm not the only one interested in trying this kind of thing out, I'm looking forward to starting to make patterns, be interesting to see if it's possible to do a 24l tank, I doubt there's room really so I may have to think about another higher remote reservoir set-up for later if I decide to take up endurance... (edit: for now I'm aiming for 12l, should manage a ten lap race of Dono + waiting / warmups / re-starts, the old sports touring racer is surprisingly frugal) Link to comment Share on other sites More sharing options...
kanerdog1x1 Posted January 8, 2013 Report Share Posted January 8, 2013 hokay, any good? Link to comment Share on other sites More sharing options...
Superdunc Posted January 8, 2013 Report Share Posted January 8, 2013 What Diameter are the large filler necks and how much please? Link to comment Share on other sites More sharing options...
kanerdog1x1 Posted January 8, 2013 Report Share Posted January 8, 2013 pm'd Link to comment Share on other sites More sharing options...
vfiend Posted January 9, 2013 Author Report Share Posted January 9, 2013 That, sir; is very helpful. Do you have prices on swaged pipe (probably 8mm? I havent taken a vernier to anything yet) and large filler neck? Also o/d height of filler neck would be appreciated. Any a side note does anyone have an opinion on getting tanks carbon wrapped? Would it add additional strength? Or just hide signs of fatigue?.. Would the addition in weight just mean I may aswell have made it in steel? Link to comment Share on other sites More sharing options...
kanerdog1x1 Posted January 9, 2013 Report Share Posted January 9, 2013 Pm'd Link to comment Share on other sites More sharing options...
Evilchicken0 Posted January 14, 2013 Report Share Posted January 14, 2013 The idea of wrapping in carbon would be to add extra strength but as the ally sheet is going to be strong enough you probably wouldn't need it. If your thinking about crash damage to the tank - the subframe should give it that protection and it would be flexible enough to deflect. You could take this further and use the tank as the subframe hanging it off the mainframe sticking the seat foam directly to it. Link to comment Share on other sites More sharing options...
Farmfab01 Posted April 7, 2014 Report Share Posted April 7, 2014 Did you ever get any further with this project chap? Link to comment Share on other sites More sharing options...
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