Gear change lever spline size

[RobSawyer]

Hello - I’m just rebuilding a mid 50s NH350 from boxes of bits and have a couple of concerns.

I have a GB gearbox installed, stamped 40 M 55, and I’m looking for a gear change lever for it. Ones I’ve seen advertised on various sites seem to be larger than my 11/16 or 17 mm spline - Is this the right size?
Does anyone have one surplus to requirements please?

Second thing (twofold) is the difficulty I’m experiencing in engaging the clutch actuating arm when putting the outer cover on, it seems extremely loose with an inch or so of side play at the cable end. It seems the cable I have (from Dragonfly) seems too long but it’s difficult to be sure when the arm is so imprecise. The clutch is installed and I have tried experimenting with a push rod plus ball bearing to lengthen the action but I cannot tell if the actuating arm is contacting the end of the rod precisely. Any thoughts or advice would be gratefully received.

[Simon.Gardiner]

Hi Rob
The spline size (OD) on my GB appears to be 0.735" (kickstart and gear lever splines are the same).
There can be quite a lot of side play at the cable end of the lever. You'll have looked at the gearbox exploded views (eg on Drags site?), the lever fits in a fork on the end of the push-rod extension that fits from the kick start case end. You might be able to check that it's in the right place with a torch through the filler cap hole?
Use the adjustments (screw thread on pivot of clutch operating lever and the cable adjuster in the gearbox) to get the lever as close to a right-angle with the push-rod as possible, without letting anything foul the filler cap when 'relaxed' (otherwise the clutch will slip).

HTH

SG

[RobSawyer]

Thank you for your help Simon. My splines are 0.672” ID and 0.700” OD. It’s useful to know it’s usual to have side play in the arm.
I hadn’t looked at a diagram but I shall do so now, but the arm seems to be correctly positioned in the end cover - it just seems to be so vague after the cover is on I thought it couldn’t be right.
It seems the cable inner may well be too long but I want to make sure it’s nothing else before I shorten it. Thanks again.

[dave.owen]

Rob, club spares have the correct gear levers

Dave

[keith.mettam]

Rob, (as per S G's info but a bit more detail)
Clutch adjustment-wise, I would slacken the handlebar cable adjuster right off and disconnect the cable at the gearbox end then adjust the gearbox clutch operating lever so you have about 3/16" free movement at the tip of the lever. This is done by removing gearbox filler plug (so you can check arm movement) and undoing the little housing held on the outer cover of the GB gearbox by two screws (remove the screws). Adjusting the hex nut under it (in increases free play and out reduces it, if my memory is correct). You can do this by rotating the housing one way or the other without removing it completely once you have taken the screws out. Re-fit it and check clutch arm free-play, repeat procedure until you are happy it is ok. Re-fit the clutch cable and adjust the cable to have about 3/16" at the handlebar lever.
Good luck with it,
Keith.

[RobSawyer]

Thank you Dave for the gear lever info and Keith for the detailed course of action. I’ll let you know how I get on a bit later in the week.