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

MK3 Restomod

Discussion in 'Norton Motorcycle Rebuilds' started by lcrken, Jan 23, 2016.

  1. lcrken

    lcrken VIP MEMBER

    Joined:
    Mar 15, 2009
    I wouldn't recommend using an alloy clutch basket with the MK3 chain drive primary. A couple of decades back I tried using an alloy engine sprocket and clutch on a 750 Commando racer, and the sprocket teeth on both wore out almost immediately. I think it was from Fair Spares, but I'm not sure after so many years. It might work better with one of the modern high tech surface treatments to provide a much harder wear surface. I don't think the one I tried was even anodized, just bare alloy.

    Ken
     
  2. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    Ken,

    I agree with you, and many others have made the same experience. Phil Pearson finally switched to a steel sprocket for his Goldie / Suzuki clutch adaption. The NEB clutch also employs an alloy basket and a steel sprocket bolted on. I was thinking in the same direction, progressing the design even further by using a sprocket design similar to the "ring" type now offered for the Mk3 rear wheel carrier. The inner diameter sprocket support would be part of the basket, saving even more weight. I will do some modelling shortly to exploit the possibilities.

    -Knut
     
  3. KiwiNeill

    KiwiNeill

    Joined:
    Jul 25, 2011
    mdt-son
    You could get close to a 1500g -3.3lb weight savings from an alloy clutch basket as the steel one is 1962g and an hard anodised, all alloy copy would be around 670g.
    I prefer the durability of the O.E. steel clutch basket however and maybe things like a hard anodised rivetted backplate replacing the steel one would help get the total weight reduction of a duplex Barnett setup closer to 4lb and within 1- 1.5lb of a typical belt drive weight going by the 30mm Old Brits kit.
    That,s probably as far as I,ll go with it, just bolt it all up and walk away, got a hydraulic clutch setup to do next.
     
    Last edited: Dec 4, 2018
  4. bill

    bill

    Joined:
    Jun 1, 2003
    i have seen that before . good luck finding one and it would be a fair amount of work to make one, to truly do it right you would also need to angle the clutch splines to match the hub angle. with what i have it is still a very light pull on the clutch with NO slipping so i am happy with it as is.

     
  5. lcrken

    lcrken VIP MEMBER

    Joined:
    Mar 15, 2009
    More progress. I got some thinner plates from Old Britts and narrowed them to match the ones I have. I ended up with two .065" thick plates and two .075" plates. That put the top of the clutch pack almost exactly flush with the end of the splined center hub. This picture shows it pretty well.

    Clutch Pach Height 1200.jpg

    This is a shot of the completely assembled primary drive, finally!

    Open Primary 1 1200.jpg

    And this is how it looks with the CF cover on. The patterns on the cover are mostly anomalies from the camera flash. The appearance is much more uniform than it looks here.

    CF Cover 2 1200.jpg

    I've also finished the modified seat pan, and have a new cover to install. I've refurbed a pair of period AP Lockheed racing master cylinders, and am in the process of making up new hoses. The clutch is finished, but I'm waiting to sort the headlight mounts before finishing the brake lines, just to make sure there are no interference issues. This is a shot of the bike as it is now. I've stolen the carbs for the landspeed bike, so I'll have to either put them back, or fit something else.

    Left Front 1200.jpg

    Ken
     
  6. 84ok

    84ok

    Joined:
    Aug 10, 2014
    primary cover is gorgeous!
     
  7. o0norton0o

    o0norton0o

    Joined:
    Apr 27, 2015
    Awesome Ken, Just one thing... I looked at this picture below and there's no exposed threads on the shaft end to use a dyno dave style clutch rod seal. Seeing as how you are going dry primary case/belt drive, are you considering milling down the nut in the picture to fit a clutch rod seal ?

    [​IMG]
     
  8. lcrken

    lcrken VIP MEMBER

    Joined:
    Mar 15, 2009
    Thanks, Jon. I'm happy with it. It took me three tries, and there was a real temptation to do a fourth one and get it absolutely perfect, but I managed to resist:).

    Ken
     
  9. lcrken

    lcrken VIP MEMBER

    Joined:
    Mar 15, 2009
    I wasn't planning to. I haven't really had any problems with leakage on the other belt drives I've used, so I'm not expecting any with this one. If I do have a problem with it, I have one of Dave's seals on the shelf, and I'll see about fitting it. FWIW, I do use a slightly larger diameter clutch push rod than stock, so there's not as much clearance for oil to migrate through.

    Ken