850 Gearbox

David,

Those two bolts retain the gear change selector camplate and quadrant spindles, which is why you are noticing gears changing when you apply torque to them.  Both have an o-ring seal behind the bolt washer and these may need replacing if oil is getting past.

Andy

Dave, you will be okay, as as the gear change sequencing can only be altered with the gearbox inner cover removed. You are are just selecting gears by moving the camplate with the bolt. Andy

Hi Dave,

Make sure you don`t give it too much pressure on the spanner as it`s possible to break teeth off the camplate gear.

Best regards, Al.

You really should get a manual anyway - you’ll need it

john

I'm pretty sure John didn't answer the question because the question had already been answered, so why be rude to him?  We are all prepared to help each other. "There's no such thing as a silly question...only a silly answer". But, as John quite rightly says...you should do yourself a favour and get a manual. Looking after a 40 plus year old Norton is not the same as relying on your local car dealer to service a new Nissan.

All right...but I don't think he meant to be rude.  You are correct that it's not easy to find good drawings of lots of parts and I've not seen a section through that detail.  The external nut is pretty much a continuation of the design from the Sturmey Archer box fom the late 1920's, when the cam plate was operated by an external lever onto effectively the same point. On later bakes the change mechanism all went inside the box.  But, if you could add lever to the nut (and reach it somehow) you should be able to use it to change gear....might be handy if you lose the brake positive stop on the road. Put a spanner on it to find a gear, bump start in 3rd, and rude home slowly on the clutch? I couldn't do it myself but no doubt there are heroes about who can bump start an 850 Commando.

It's usually so filthy down there on my bikes that I'd never be able to tell if that point is leaking or not. I think the earlier Doll's Head box has a cork washer, but oil often leaked from all sorst of mysterious places on earlier bikes.  I've no idea when an o ring arrived.

O rings are not close to ideal for rotation. Lip seals are far better.  I don't know if the 850 has any. But RGM and others sell X rings to replace the O rings on the kick-start and gear change levers, and they do a much better job of keeping the outside of the box clean.  Perhaps a keen owner might fit one on the nut/shaft you are looking at. I'd prefer to ride it but if you do work on the box in the future it might be worth considering.

Well, I think in this case at least the Haynes manual and Norman White's book are not to blame, perhaps it would pay if you had another read/look.

In the Haynes copy I have:
Page 54 - Chapter 2, paragraph 3, section 5:
  describes removal of the two bolts that secure camplate and quadrant.
Page 59 - Chapter 10, paragraph 10, sections 3 and 5:
  describes refitting the same bolts.
Page 56 - Fig. 2.2  Gear cluster and gearbox shell 
  shows the bolts (26), the washers (27) and the O-rings (25)

In the copy of the White book I have, there is enough text and pictures in chapter 9 - transmission that give clues about these bolts.

On internet, you may have missed Old Britts fine write-up