Laydown gearbox gear selection

I have exactly the same problem withthe rebuilt dolls head gearbox for my 1935 ES2. I can select 1st and 2nd gear but not 3rd or 4th. Like you I was wondering whether all would be OK once fitted to the bike but I'm not convinced.

John

I posted a similar problem seeking advice last August with the Laydown box in my 1956 Dommie99. Apart from a response from a lady in Yorkshire that a'56 Dommie shouldn't have a laydown gearbox, there were some useful suggestions which can be read here: http://www.nortonownersclub.org/noc-chat/technical2-heavy-twins-forum/742407666?b_start=0#261807464

However, none of these sorted the problem.In my case I could frequently not get beyond second gear unless I first lifted the gearlever slightly with my toe before making a downward selection for either third or fourth.You don't have to do it immediately before the selection, as long as it's done once in second. Perhaps Andy and John you could check if this works with yours.

Having ruled out all the other remedies suggested, and convinced that it had to be a problem with the selection mechanism, not the main gearbox, I acquired a scrap laydown box to swap over in turn the pawl carrier, ratchet plate and the individual pawls, each time using the new springs I had obtained from the NOC shop. Unfortunately the problem persisted.

I gave up on it for a month or two until by chance a similar situation arose on the Dollshead box on my pre-war 16H. I thought it had caught something nasty from the Dommie until I realised I had lowered the position of the gearlever on the 16H in an effort to make gear changing less of a contortion. I returned the gear lever to the horizontal and the problem went away. This prompted another look at the Dommie gear lever and it was set downwards at about 15?. I refitted this to the horizontal and was amazed that the gear change problem I had, whilst still occasionally occuring, was not as prominent as before. I decided to have another look a the selector mechanism.

I managed to reproduce the problem on the bench using the scrap laydownbox with just the camplate, quadrant and selector mechanism fitted. The lower pawl was not clicking fully into position when the carrier plate sprung back. If I turned the box upside down in the vice, the upper pawl did the same. By lifting the gear lever, as I was doing when riding, you could hear the pawl click into the correct position. Although I was using a new pawl hair spring, it was not functioning efficiently to push the pawls into the ratchet. A little reshaping of the spring remedied this and I also took the opportunity to gentlytidythe striking edge of the pawls with a dremel disk (replacement laydown pawls seem non existant). I also fitted a shim washer under the head of the pawl pin to reduce the float between the pawls and the carrier plate.

Early days so far as this was only achieved very recently having spent hours on the problem and several strip downs, but fingers crossed it seems to work.

Hope this might be of help to you both.

Brgds,

Pete

Hadasimilarproblem with my laydown box after rebuilding.... well it was as bad before.

I could get gears on the bench but not when rolling

This advice was so helpful http://www.nortonownersclub.org/@@search?SearchableText=Paul%27s+type+of+shifting+issues

I adjusted the springs as prescribed, also set end float on shafts and the problem was fixed, I could roar up the road and get all gears

Don't know if it was endfloat or springs tho

Laurence

Thanks for the information chaps.

Andy: no not fitted to the bike yet. Its the spare gearbox which I intend to fit to replace the one currently in the bike which often jumps out of 3rd gear. When this happens I have to go via 4th in order to select 3rd. I'm now wondering whether to try and sort this one out.

I recall assembling my lay down on the bench, and not being able to find anything, and when I did, I didn't know what it was. I pulled it apart, and double checked everything and when I put it back together with allthe partswell oiled the selection seemed to improve slightly. Once installed in the bike, with the engine running, all was well.

Re end float

I don't know what the standard boxes end float should be but if very large due to worn partsit could affectgear engagement

I have modified the box with RGM close ratio gearset so had to make thrust washers etc to suit the different mainshaft bearing in sleeve gear and locate the shaft laterally