1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

repairing interstate tank

Discussion in 'Norton Commando Motorcycles (Classic)' started by seattle##gs, Oct 8, 2018.

  1. seattle##gs

    seattle##gs

    Joined:
    Oct 28, 2014
    I have an interstate tank and the front studs are in poor condition and badly bent foreward. I want to straighten them, remove the stud, and install a pair of rubber muffler mounts.
    Is this a job better done cold or with heat? I am always very nervous about using an open flame or welding on a tank. I can wash it out and fill with CO2 or Argon during the process. The threaded boss has tipped in the bending process so it will require some careful tapping with a punch to make things level. Chances are good that a leak will form. Then I have to remove the studs. I tried double nutting one of them with no luck but I did not go for broke on the process. The threads are poor. Do not know if the studs have locktite or epoxy. Again heat may be the solution. The owner would like to preserve the paint if possible. If the worst happens I can do major surgery and cut out the threaded boss, make a flanged threaded insert and bring things back to normal...sort of. Paint will suffer. He does not want a repro tank.
    Anyone had to do this?
     
    Tags:
  2. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    Yeah
    I filled the tank with co2 and heated the studs till they were bright red hot. After they cooled they unscrewed easily.
     
  3. seattle##gs

    seattle##gs

    Joined:
    Oct 28, 2014
    will do. I will call tomorrow, I have cylinder head questions, RH4
     
  4. jseng1

    jseng1

    Joined:
    Nov 26, 2009
    I just welded a tank. I flushed it, filled it to the brim with water and soaked it a couple days & nights. Drained it thoroughly. Then I removed petcocks and cap. mounted a small 12 volt computer fan so it forced air into the cap opening an out the petcock holes. Ran it several hot days & nights until there was no hint of gas smell. Taped a torch to a long pole and stuck a flame into the opening to test - nothing happened, welded no problem.

    Of course purging with argon or co2 is safer.
     
  5. 850commando

    850commando

    Joined:
    Nov 1, 2014
    If the studs are original, then there should be no problem, they threaded into a sealed collar and there should be no problem after draining and washing the tank, to add some heat to remove them, be aware that the tank metal is quite thin around the collar and break out of the collar can occur

    [​IMG]
     
  6. Peter R

    Peter R

    Joined:
    Dec 13, 2010
    I concur with what 850commando said, the metal of the tank cracks easily around the circumference of the collar, (don't ask me how I know)
    Had one of the collars repaired on my tank due to a minor leakage.
     
  7. Anglophile

    Anglophile

    Joined:
    Mar 6, 2010
    I’ve got a similar dilemma. Hairline crack. It hasn’t had gas in it for years and years. No smell. Dry as a bone but still hesitant to take it to someone to TIG or solder.
    [​IMG]
    https://flic.kr/p/PK5V5d
     
  8. 850commando

    850commando

    Joined:
    Nov 1, 2014
    I would expect that with the level of vibration produced by the running engine this is one area were we should not be surprised to see this kind of failure. i have made up a cover plug which was tig welded into place. but the tank is really thin and it was a real bear to weld without blowing through...
     
  9. rvich

    rvich VIP MEMBER

    Joined:
    Jul 25, 2009
    Brazing is often used for this kind of repair. Essentially doubling the thickness of the steel.
     
  10. N0rt0nelectr@

    N0rt0nelectr@ VIP MEMBER

    Joined:
    Sep 15, 2014
    I watched as an old motorcycle mechanic and welder/body-man repaired my Interstate tank. I was thinking like you that I needed to flood the tank with non flammable gas before welding. He waved his torch over the filler neck after I had left it open for several days. The torch burned off any residual fumes. It is all in what you know and I know that I wouldn't want to weld on a tank but he could and had no problem.

    John in Texas
     
  11. bill

    bill

    Joined:
    Jun 1, 2003
    brazing is not a good option. it is almost impossible to get it clean enough to keep paint on the brazed place. also if someone has to weld it than you again have a mess as you cant weld it until ALL the brass is removed.

     
  12. seattle##gs

    seattle##gs

    Joined:
    Oct 28, 2014
    tig is what I am considering. I will get on to it in a couple of weeks.
     
  13. franko

    franko VIP MEMBER

    Joined:
    Dec 29, 2013
    I welded the holes shut that the wrong studs caused in a triumph tank. Oxygen/ acetylene worked best in my case. Carbon flame kept the porosity away.
    It was easy to control the heat.
     
Loading...