commando/amc gearbox options/compatability

Discussion in 'Norton Commando Classic Motorcycles' started by 84ok, Mar 20, 2018.

  1. 84ok

    84ok

    Joined:
    Aug 10, 2014
    i'm always on the lookout for gearbox/parts suitable for commando use but not clear on what all parts may be compatible?

    just looked at an ebay ad that showed a box for use on commando 68-74 understanding the e/start 75 is diff from the rest

    that mean an atlas, or other norton model use of the tranny wont work? or other uses of the tranny in other makes & models that use it, or any other parts?

    i think the cases or mounting shells when used on other makes can be incompatible with commando

    what all is usable for commando years 68-74?

    some info
    http://www.petersclassicbikeparts.nl/contents/en-us/d142.html
    http://preservationcycle.com/index....-norton-commando-gearbox&catid=86&Itemid=1739

    https://www.nortonownersclub.org/noc-chat/technical1-singles-forum/934271355

    https://www.accessnorton.com/NortonCommando/gearbox-identification.18335/

    https://www.accessnorton.com/NortonCommando/commando-1974-gearbox.17821/

    - edit: tranny is short for transmission, apparently often used, even alone in ads for norton boxes, or bikes in general
     
    Last edited: Mar 21, 2018
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  2. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    The AMC box which is used in a Commando has a longer main shaft (about 6mm) to accommodate the diaphragm clutch.
     
  3. 84ok

    84ok

    Joined:
    Aug 10, 2014
    will that mainshaft fit an atlas or other boxes? along with the other commando internals, then bolt on to a commando?
     
    Last edited: Mar 21, 2018
  4. baz

    baz VIP MEMBER

    Joined:
    May 26, 2010
    Someone else should chime in with the differences in earlier gearboxes ,
    I really can't remember what the differences are?
    But in answer to your question about the atlas gearbox yes you can fit a commando main shaft into the atlas gearbox, all i actually changed was the main shaft it still retains the atlas gears etc have done this myself in the past , I hope this helps
     
  5. 84ok

    84ok

    Joined:
    Aug 10, 2014
    absolutely! tx!! exactly what i'm after, key info new to me that tells me what i can make work with commando,

    prior to this, my searches for g/b parts was limited or 68-74 specific,
     
    Last edited: Mar 21, 2018
  6. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    I'm pretty sure any AMC box will fit into a commando and the internals are all similar, except for the mainshaft. On my bike, I use a TTI gearbox with a single row primary chain with a Manx clutch. The TTI is intended to be used with the diaphragm clutch, so the mainshaft is too long. I get around it by using Jawa Speedway engine sprockets floating on a splined carrier I had manufactured. It depends on what you use the bike for - I would not do that on a road bike.
     
    Last edited: Mar 21, 2018
  7. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    Many of the pre-1960 Matchless and AJS had AMC boxes which can be used in a commando, if you change the mainshaft or use an early clutch .. If you don't change the mainshaft in the earlier box and use the diaphragm clutch, there is an alignment problem of about 6mm.
     
  8. triumph2

    triumph2

    Joined:
    Aug 13, 2008
    The main gearbox casting used in AJS and Matchless gearboxes had the mounting lugs in a different location to the Norton boxes.
     
  9. Ron L

    Ron L VIP MEMBER

    Joined:
    Feb 27, 2004
    The Atlas and other slimline featherbed gearbox cases are wider at the top boss for the fixing bolt. The Commando uses a spacer here while the Atlas does not. You could mill the top bolt boss on an Atlas case to match the Commando and use the Commando spacer. I don't think you can fit the Atlas case in the Commando cradle without milling it.

    The Atlas and G15/N15/P11 outer gearbox covers are threaded to accept the clutch cable adjuster and is located further rearward than the Commando cover. All inner gearbox covers are the same for Atlas, Commando, N15/P11.
     
  10. 84ok

    84ok

    Joined:
    Aug 10, 2014
    from above link
    http://preservationcycle.com/index....-norton-commando-gearbox&catid=86&Itemid=1739
     
  11. lcrken

    lcrken VIP MEMBER

    Joined:
    Mar 15, 2009
  12. lcrken

    lcrken VIP MEMBER

    Joined:
    Mar 15, 2009
  13. hobot

    hobot

    Joined:
    Oct 19, 2005
    Rest assured Atlas shell is identical to Commando except the Atlas shell does not force ya to fart with the stupid thick wedge spacer, just fit gearbox align holes, shove in bolt nip up done. Atlas shells are about 1/2 cheaper last time I shopped 15 yr ago. I've a Qualfe shell that Icrken Canaga did a bolt hole weld up repair for me. I like its beefy looks. Did not use as eventually afforded a New Zealand ITT 4 spd.

    So far no cost effective way to restore wallowed out AMC bearing bores so eventually will run out. About 15 yr ago called world wide looking for Commando gb to learn the major shops each had a big pile of cases that by now likely scraped out. The only place I know that still has piles of good Commando and Atlas shells, plus other Commando items, is Baxters Cycles.
     
  14. marinatlas

    marinatlas

    Joined:
    Nov 4, 2007
    Do not forget also the inner cover is different in some manner of fixing the kick spring , (between Cdo and early Atlas ), as the Cdo one is fixed to a "stud" and the earlier one have a peg going into a hole in the inner case , the springs are different , the late model is far better , more positive return action , and less possibility of going off .......
     
  15. oldmikew

    oldmikew

    Joined:
    Jul 25, 2015
    Yes , and the AMC box fitted to the Model 50 had a shorter mainshaft than its contempories
     
  16. pierodn

    pierodn

    Joined:
    Nov 10, 2012
    a
    and the lugs tunnel (not for Atlas) are thin instead commando one so you must drill to enlarge.
     
  17. 84ok

    84ok

    Joined:
    Aug 10, 2014
  18. 84ok

    84ok

    Joined:
    Aug 10, 2014
    related post from another thread
    https://www.accessnorton.com/NortonCommando/gearbox-identification.18335/page-2#post-272972
    new topic related to thread
    https://www.accessnorton.com/Norton...ce-bulletin-mixing-gears-or-made-pairs.24865/
     
    Last edited: Mar 23, 2018
  19. 84ok

    84ok

    Joined:
    Aug 10, 2014
    http://preservationcycle.com/index....-norton-commando-gearbox&catid=86&Itemid=1739
     
  20. hobot

    hobot

    Joined:
    Oct 19, 2005
    In my newbie ignorance after world wide vendor with decades seasoned experts via expensive phone call pestering for replacement of Commando AMC gb shell i got good 1/2 price Altas used shell that all the '72 Cdo parts fit in finer than cdo numbered parts. Solved it for me to move on to other issues. I just want to be a pilot so your call how to get there too. I had so many issues with original AMC Cdo gbox I ran out of gaskets so just splaped together with goop to find out that solved the lay shaft shim issue to boot.
     

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