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748 Expansion Tank

Discussion in 'Builds & Projects' started by Birdie, Aug 5, 2014.

  1. After my first expansion tank leak at the weekend I fitted my used spare and as I had the old one to use as a template decided to have a go at making my own ally one, done plenty of steel welding but never ally so I will have to practice and if I can't do it I have a friend who can.
    So I started with a cardboard mock up and used that for templates for the 3mm ally plate, after cutting and bending the different shapes I now have a tank look alike to tack together ready for a test run and to mark the best place for the hose connections. Hope there aren't too many alterations needed.
    I have often wondered if these could be made out of carbon fiber and if so why has no one ever done it as it does seem to be a regular problem.
    Steve
    2014-08-05 12.18.27.jpg 2014-08-05 12.18.59.jpg 2014-08-05 15.00.50.jpg 2014-08-05 15.00.29.jpg
     
    #1 Birdie, Aug 5, 2014
    Last edited: Aug 5, 2014
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  2. admire your efforts !

    Didn't someone like @Dukedesmo make an alloy one, after something like 5 leaking plastic ones - rings a vague bell with me.
     
  3. I know he has one on his 916 but I think he had it made for him.
    Steve
     
  4. i did say my memory was vague!!!!
     
  5. so 10/10 for making it yourself Steve ; ) you are a brave bloke if you are going to A/ Weld it as your first ever aluminium exercise B/Show it to us afterwards. I would get your mate to weld it and fold up a second one for you to try but Good Luck either way. I have done some in the past but it's all about the eyesight these days and looking out for the slightest change while bringing it all up to temp slowly. Maybe you will TIG it? which is slightly easier.
     
  6. Just been watching some you tube footage of Mig welding ally for beginners, looks as though I might make a mess of it to be honest, I have some scraps so I will try on them first, if its to much them I have a mate with a tig to call on.
    Steve
     
  7. I bought one from a chap on a US forum who was making them but doesn't any more.

    I did think about making one but much easier to let someone else work out the dimensions etc.

    And, yes I had several fail, including 3 in one year and one that leaked within 10 miles of first fitting.
     
  8. Got the two weld on spigots for the hoses yesterday, now just got to remove the tank and airbox again to have a test run.
    2014-08-09 09.53.49.jpg

    First ever attempt at Mig welding alloy, Mr R (Steve) I went for the 3mm hoping I wouldn't burn holes through the thinner material, if this one works I will have a go with some 14 or 16g as you suggest.
    2014-08-09 09.56.42.jpg
    Lucky I have some spare sheet as a lot more practice is needed yet, I would like to finish it myself but if all fails I will have to by buy mate a few beers to tig weld it for me.
    Off to practice now.
    Steve
     
    • Like Like x 1
  9. That's a nice first effort, I struggled with my first arc welding efforts and they were really poor, fortunately a friend of mine is a great fabricator and I must admit I wouldn't even consider having a go at alloy.

    I admire you for at least trying, I hope it works out for you, good luck
     
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  10. Nothing wrong with 2.5/3 mm Steve considering you are welding it. You could do me a favour and weigh both original (bare) and your stack of 3 mm plates pre-weld plus spigots and cap just out of interest. If you can repeatedly weld up a 16g version faultlessly (no leaks/pressure tested) then you could easily turn professional.
     
  11. Hi Chris, the bare plastic one with no fittings or ally filler neck weighs 330g my 3mm ally one with spigots and neck welded on weighs 430g. 2014-08-09 15.39.49.jpg
    Spigots and neck are welded from the inside of the tank.
    While practicing I have found that you have to have a lot faster spool feed and a faster weld speed compered to metal.
    My first attempts were one handed as I only have a hand held mask I think I can make a better job when my full face helmet mask arrives so I can steady the welding hand a little.
    Steve
     
    #11 Birdie, Aug 9, 2014
    Last edited: Aug 9, 2014
    • Thanks Thanks x 1
  12. Must add I have had a test fit and it is spot on, no need for any adjustments, very pleased as I only had the plastic one as a guide and they have all rounded sides to contend with. Might be next weekend before I get it welded up though, awaiting a new mask.
    Steve
     
  13. Aint you a chippy?
    Make one up outta MDF...:upyeah:
     
  14. As it was raining today I couldn't wait until the new mask arrives, so I have put it together as best I can. I found that pushing the weld gave a better finish than pulling although alien to what I am used to with metal. 2014-08-10 15.13.50.jpg
    I have ground some of the welds off to give a better fit around the headstock.
    2014-08-10 15.19.21.jpg

    Just got to pressure test it now, quite pleased with the outcome as yesterday was my first attempt at ally welding.
    2014-08-10 15.19.36.jpg
    Just a bit of splatter to clean off.
    Steve
     
    • Like Like x 4
  15. Nelson yes MDF would have been easier!!!
    Steve
     
  16. excellent stuff Steve - are you taking orders yet?
     
  17. There is a demand I'm sure, perhaps with more practice it could be a nice sideline when I retire, mind you that's 3 years away yet.
    Steve
     
  18. I did something similar with my 996, no problems since!
    If you unbolt the original tanks cap it has a bolt on flange so makes it easy to use.

    DSC_7506.JPG
     
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    • Agree Agree x 1
  19. be interested to see if that pressure tests ok...
     
  20. There's not a lot of pressure in a cooling system! If the plastic can (almost) handle it then alloy is sweet :)
     
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