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

Gearbox shifting problem

Discussion in 'Norton Commando Motorcycles (Classic)' started by seattle##gs, Oct 11, 2019.

  1. seattle##gs


    Oct 28, 2014
    I put a gearbox back together with many new parts. The GB was supplied by someone else completely torn apart and in a box. Even the quadrant and cam plate had been removed which is rare. I assembled everything with new bearings checking for smooth movement throughout. I assume I indexed the cam plate and quadrant correctly because I can shift into all 4 gears...sometimes. The outer cover is off and shifting is done with a prybar on the quadrant. Turn the mainshaft by hand. sometimes I can get all 4 gears, usually it hangs up in one gear or the other. Everything is lubed well with #20 oil. The GB is mounted in a stand on the workbench. I've pulled it apart 5 times now and no clue as to the problem. If I loosen the indexing plunger the shifting will get a little bit better. If the GB is empty of gears it will shift up and down reliably. The shifter forks look good. The shift fork rod is slightly bent on the right side but very little. Any ideas?
  2. storm42

    storm42 VIP MEMBER

    Jul 20, 2011
    I would fit the outer cover and try with a gear lever fitted, are you turning the mainshaft independently of the output shaft?
  3. norton bob

    norton bob

    Nov 29, 2013
    I had a similar problem,I found 3 things that after attention solved the problem. One of the gears on the mainshaft seemed slightly sticky but not all of the time ,after close inspection of the splines in the gear and on the shaft I found some small rough patches which I pollished out with fine carborundem paper. The bush in the Kickstart shaft that supports the end of the layshaft was a bit worn and was allowing the shaft and gears side play and the kickstart to move under hard acceleration.The back of the clutch spider was in hard contact with the end of the sleeve gear and I fixed that with a new spider. I think the first one is the best bet.
  4. concours

    concours VIP MEMBER

    Dec 29, 2011
    Um, put in a NOT bent one, to start. It’s not rebar. It kinda matters...
    MexicoMike and kommando like this.
  5. concours

    concours VIP MEMBER

    Dec 29, 2011
  6. Niagara850


    Jul 7, 2010
    Bent fork aside. The quadrant could be out by a tooth with the cam wheel. Check if you are high or low in the quadrant inner cover window. You will be able to shift thru the gears with the outer cover off but it doesn't work properly with it on. Loosen off the cam plunger bolt to make it easier to turn. Remove the inner cover and layshaft so you can see the cam wheel and plunger. The quadrant will disengage the cam wheel when pushed it all the way down with the inner cover removed. Adjust the cam wheel position relative to the neutral indent to the plunger. I set plunger just in front of the neutral indent and engaged the quadrant to find the correct position. It might take a few tries.

Share This Page