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Gearbox rebuild tips

Discussion in 'Norton Commando Motorcycles (Classic)' started by baz, Jul 26, 2019.

  1. baz

    baz VIP MEMBER

    Joined:
    May 26, 2010
    It's been at least 15 years since I rebuilt the gearbox on my commando
    I replaced every bush / bearings etc including the layshaft roller bearing conversion and a Steve maney outrigger
    But the gearbox is in need of another rebuild
    The Kickstart is moving under exelleration
    It's noisier in second gear
    It doesn't like going into first gear
    And it's generally tight to change gear, tighter than it was anyway
    I'm looking for tips for the above problems
    What's causing it to not want to go into first? Sometimes it feels like it's in and it jumps out at the most inoportune moments
    I assume the layshaft roller bearing is knackered as the kickstart is moving etc?
    Any help on building this box better would be appreciated
    I do ride the bike very hard hence the outrigger
    Just trying to save a bit of down time when I pull the gearbox cheers
     
  2. kommando

    kommando

    Joined:
    May 7, 2005
    Primary chain tension and clutch would be on my list to go at first.

    Also look at fitting a needle roller inside the kickstart shaft instead of the bush, you only need to modify the layshaft.
     
  3. baz

    baz VIP MEMBER

    Joined:
    May 26, 2010
    I run a belt drive ,I thought I ran it on the loose side but it's something I can easily check
    I've not seen the needle roller conversion? Sounds interesting
    Cheers
     
  4. Onder

    Onder

    Joined:
    May 11, 2010
    Yes Ive often wondered whether that was worth the bother other bikes besides Commando use a bush
    yet Ive never seen it actually done.
     
  5. kommando

    kommando

    Joined:
    May 7, 2005
    Needle roller

    SCH1016B Needle Bearing 5/8"x7/8"x1" inch

    Straight replacement inside the kickstarter shaft of the bush, layshaft that runs inside the kickstart shaft needs grinding down to fit.

    When my Portuguese layshaft bearing was replaced in the late 80's I did the needle roller at the same time as the bush was worn and the gearbox has not needed touching since.
     
    fiatfan likes this.
  6. fiatfan

    fiatfan VIP MEMBER

    Joined:
    Aug 9, 2015
    Interresting! About grinding down the layshaft, there´s no risk of removing the hardened surface on the shaft? I also wonder if there´s a fix to solve a bad fit of the steel shaft bush in the inner cover? My new bush is not tight in any way, falls right out if you turn the cover around..... Will it be good enough to use a good bearing retaining compound?
     
  7. kommando

    kommando

    Joined:
    May 7, 2005
    I have never took my gearbox apart to look at the layshaft to see if the hardening is still there but if it was an issue there would be symptoms such as the kickstart moving down and there is no such evidence. You take 60 odd thou off the diameter which takes off the scroll and leaves a hardened surface.

    I would use loctite on a outer cover kickstart bush.
     
    fiatfan likes this.
  8. fiatfan

    fiatfan VIP MEMBER

    Joined:
    Aug 9, 2015
    Thanks for the info, will absolutely look in to this!
     
  9. jseng1

    jseng1

    Joined:
    Nov 26, 2009
    Instead of grinding down the end of the layshaft - open up the inside diameter of the bearing.
     
  10. kommando

    kommando

    Joined:
    May 7, 2005
    You have to grind the layshaft to remove the scroll groove.
     

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