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Convert 850 rear brake from disc to drum.

Discussion in 'Norton Commando Motorcycles (Classic)' started by Clanger, Jul 4, 2018.

  1. Clanger

    Clanger

    Joined:
    Mar 19, 2014
    Hi Gang,

    So, is it at all possible to convert an 850 from LH Gear change , disc rear brake to Mk2 spec - drum rear brake and RH gear change?

    I guess its not easy?
     
  2. RobinKent

    RobinKent

    Joined:
    Jan 31, 2010
    Yes if you are willing to buy a few parts, blank off a few holes, add a brake cable end block to the swing arm, adapt a spacer or two and own basic tools. Drum rear wheel may need work to align it.
     
  3. ashman

    ashman

    Joined:
    Jul 11, 2010
    Anything is possible but one has to ask why if you wanted to go that way you should have got the right model in the first place.

    Ashley
     
  4. Tornado

    Tornado VIP MEMBER

    Joined:
    Dec 5, 2017
    Gotta ask...why would you want to migrate a MKIII setup to a MKII? Likely the biggest challange will be the gear shifting side change...needs tanny mods, foot peg/lever changes.
     
  5. Ron L

    Ron L VIP MEMBER

    Joined:
    Feb 27, 2004
    Unless you already have the necessary parts, it likely will be less costly to sell the Mk3 and buy a Mk2 850 in similar condition.
     
    RobinKent likes this.
  6. Onder

    Onder

    Joined:
    May 11, 2010
    That odd thing aft is a poor excuse for a brake. Dont go there.
     
    concours and Tornado like this.
  7. ashman

    ashman

    Joined:
    Jul 11, 2010
    Well I find my drum brake on the back works great with a good disc set up in the front as we all know the front brake does all the work and In 43 years I have had no problems with my rear drum except for a circlip mount brakege in the drum housing, but that another story.
    Most new Norton owners have troubles with right hand gear changes after riding left gear change bikes all their lives and want to chage the other way if they could, but I do perferr the right gear change over my moden bikes, but I have no problems riding both ways changing from both for over 45 years of riding.

    Ashley
     
  8. Tornado

    Tornado VIP MEMBER

    Joined:
    Dec 5, 2017
    I'm still a newbie to mtoriding...4th season now. 90% of that on my modern 2013 Bonne...some 50k+ KM's so far. Now I have a '74 850 Norton with rightfoot shifting. Though I currently feel comfortable shifting/braking opposite to what the Bonne does....I do have trouble when I need ot brake suddenly when a car pulls into my lane without looking etc....I find myself "braking" with the right foot up into next gear!
    It's that muscle memory your brain uses in "panic" mode....not the more thoughtful, conscience brain but the reptilian/automatic brain. Top rider school trainers have taught me to perform rear/front braking at each and every stop I make, no matter how trivial, to help drill home what "normal" procedure is into the automatic nervous system. I also routinely go out and run practise emerg braking drills on empty parking lots so that my muscles know how much braking pressure is needed to make the stop without causing skids (hard to do on the Norton ;-). Esp. important when changing to different bikes.
     
  9. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    The MK3 rear brake is a really nice one.
    Its as good as the rear brake on the Daytona 955i or Thruxton R with the ABS turned off.

    The other good part is that it comes attached to a MK3 swing arm. Stronger and sealed for life.
    Switching to the drum brake and lighter swing arm would be a retrograde step.
    I suppose you could keep the MK3 swing arm and just change the wheel.

    Really though, it seems you've already got the good stuff on there.

    Glen
     
    Last edited: Jul 4, 2018
  10. Clanger

    Clanger

    Joined:
    Mar 19, 2014
    Thanks for the responses. I was just trying to get my head round whats involved. My bike is very original so I am unlikely to go that route, although I have quite a few of the required parts. I have an old dominator and I find the gearchange much sweeter, knowing how nice the amc based box can be, I don't think the MK3 crosshaft design works very well.
     
  11. RobinKent

    RobinKent

    Joined:
    Jan 31, 2010
    New bushes all round would be the cheapest way to reduce slack/improve feel. Anything else will involve imagination and money!
     
  12. grandpaul

    grandpaul VIP MEMBER

    Joined:
    Jan 15, 2008
    MkIII converted to right-foot shift, easy: my avatar. The drum brake thing will need more work...
     
  13. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    Apart from added weight, changes from Mk2 to Mk3 were the biggest improvements to the Commando ever, and could / should have been there from the outset. Why make something which works so well (*) lesser? Forget your idea and focus on maintenance and improvements of what you've got!

    * Apart from the starter and the disc brake up front

    -Knut
     
  14. Clanger

    Clanger

    Joined:
    Mar 19, 2014
    So that means that you have retetained Disc Brake and are now operating it from the LH side? More info please?!
     
  15. worntorn

    worntorn

    Joined:
    Dec 22, 2006
    I have a 650ss with right shift AMC and Commando MK3 with left shift.
    Maybe I'm a heathen but apart from the difference in position I cannot sense any difference.
    Both shift perfectly, have never missed a shift on either bike.
    I routinely shift the MK3 without clutch when passing quickly. When revs hit somewhere around 6500, just ease up ever so slightly on throttle and up shift.
    Both bikes shift better than all the moderns Ive ridden other than Thrux R
    The two BMWs and one Guzzi I sampled are agricultural in comparison. My own 2005 Daytona with its " much improved smooth shift trans" is pretty clunky in comparison.
    Vincents aren't even close.
    Ive noticed that Vincent owners don't like to talk about how crappy the shift is on their bikes.

    I can't see any operational disadvantage in the MK3 crossover shaft vs RH amc, unless you are used to RH shifting and have difficulties when switching to LH.
    Maybe the splines are worn on your MK3 setup?

    Glen
     
  16. Torontonian

    Torontonian

    Joined:
    Dec 28, 2009
    Indeed my MK 111 shifts beautifully with the new crossover shaft bushes in place. Grease the splines every time the primary is off too.
    Would not even consider doing whatever this is about. Why ?
     
  17. grandpaul

    grandpaul VIP MEMBER

    Joined:
    Jan 15, 2008
    Last edited: Jul 6, 2018
  18. rvich

    rvich VIP MEMBER

    Joined:
    Jul 25, 2009
    There are plenty of people who want Mk3 bikes that I would just shop for a good Mk2 and upgrade some of its features to Mk3 spec. You would not be doing yourself a service of taking a fairly original Mk3 and changing all that. It would cost a lot and devalue the bike.
     
    Tornado likes this.
  19. grandpaul

    grandpaul VIP MEMBER

    Joined:
    Jan 15, 2008
    Doesn't cost much at all, if you have a decent local m/c salvage shop.

    Doesn't devalue the bike one penny if you do it right. In fact, it adds exactly the value of the additional parts to convert it, because a future owner may want to do the same.