Laydown gearbox - selection problem

Advice would be appreciated on a gear selection problem with my 1956 Dommie.

After about 20 minutes use, normal selection from second up into third occasionally becomes impossible, the lever depresses but nothing engages. I found that by going to much higher revs before selection works OK. Following more expert advice, I also find that gently lifting the gear lever and then depressing gives normal selection every time, so I guess it may be a common problem. This also occurs occasionally changing from third to top. All down selections are normal.

The gearbox was recently rebuilt by a leading Norton Specialist for the previous owner with new bushes and bearings although neither of the pawl springs seem to have been changed. I was intending therefore to replace these as a matter of course but could anyone suggest what else I might look for.

Well The 1956 Dominator had the first AMC Norton Gearbox fitted , there first year after September 1955, the lay down Sturmley Archer designed gear box Made by Burman gear boxes then AMC took over the lot , in 1953, so you may have the wrong gear box in for the year of your machine,

Dont forget, there is the manufactured date & then there is the titled date. Having said that, I have 2 friends with a '56 dommie wideline featherbed with a laydown box, another friend with a '56 dommie model 77 single downtube frame with a laydown box, and another friend with a '56 model 19s with a laydown box. My '57 has the AMC box.

But really the basic lump of internals & how they work is very much the same. I had the exact same problem last year on my '57 M77 AMC box, took it all apart, checked all the shafts, bearings, cam, etc & found nothing wrong, I did double check the directoin the pawl spring goes on & the correct way it should be bent (new one wont necessarily be bent correctly) according to the Mic Hemmings video. Now it all wors great, but I dont now what made the difference?????

Skip Brolund

I've had a similar problem. It was the clutch.

Thanks Skip, reassuring to hear that I am not alone with this problem even if one can't pinpoint the cause. I guess a question of just taking it apart, close inspection, fit the replacement springs, mutter the necessary incantations and hope for the best. I do have Mick Hemming's excellent gearbox video but the section on the Laydown box isrelatively brief. The pawl springs in the Laydown box have much shorter arms and are completely symmetrical unlike the longer cranked one in the AMC box, so not the option to fit the wrong way around or reshape the arm.

I was reluctant to dent AJD's dogma on the history of Norton gearboxes, such pearls of wisdom probably have their place ! I think most are aware that the Laydown box continued well into 1956 on many models, I believe into Spring of that year, despite what it might indicate in the Bacon books. Certainly my January'56 Model 99 and a couple of others that I know of all came with Laydown boxes whereas my old 1957 Model 50, which I had from near new, had an AMC one. Anyway, interesting to learn from the lady's input that my selection problem might be because I had the wrong gearbox fitted, some comfort I suppose it being not due to something more serious, like having the incorrect shade of blue !

Hello well these machine may have been old stock 1955 models , As there was a Strike to wards the end of 1955 and in 1956 at bracebridge street works this lasted some six month so not many Norton were made , in late 1955 early1956, years this strike was over 26 redundant workers, and the AMC 1 gear box came out in September 1955 . For the 1956 year, along with the new model the Model 99 , And some of Roy Bacon book is out on his dating by 9 months late. And do not forget that Norton used stock as and when it was available old stock was use up first and there maybe times when machines went out with the lay down box or the other AMC 1 , gear boxes , and you get old stock machines that not been sold until later some may of been in show rooms for over 2 years or longer, So there for you can have a late 1955 machine not sold until 1957 there for registered in 1957, this also happen with some of the De-luxe Model like a 1960 machines not sold until late 1962, so there for registered in 1962, and not to for get the factory stamp man had to play catch up so some machine were some 3 weeks old before that got stamp marked , As I have the Bracebridge street Stamping set,

Hi Peter

sorry I can't help re gbox problem. However the spares parts books for both singles & twin models for 1956 show that these were fitted with the laydown box. The 1957 books show the AMC box. I hope this gives clarification.

If you are lucky, the problem may only be a weak, or broken, hairpin return spring. The "Laydown" and AMC gearboxes are very similar, and, I am fairly sure the same hairpin spring is common to both. If the gear lever fails to return to it's correct position (after a gear-change) the next selection will be difficult, or sometimes impossible. Only the gear lever, and outer cover, need be removed to access the spring, it is not an expensive item, and is easy to replace. Your symptoms are exactly as mentioned in the "Trouble shooting" section of the owner's handbook. Regards, John.

Hi.

Bit of a long shot this. I had a laydown box that would not select its gears - it turned out that the peg on one of the selector forks protruded through the camplate justfar enough to catch the gearchange quadrant. It was a bugger tosolve as everything seemed OK until the inner cover was fitted which moved the selector fork spindle enough for the pegto catch the quadrant. Worth checking!?!?

Regards. Ian.

Hi again Pete,

Try phoning RGM, The kickstart shaft on my '54 Dommy was leaking quite badly, and I needed an O-ring, plus a couple of bushes. Not a big order, but it arrived here, in Spain, only 5 days later. John.

hello my 54 domie had a cam plate problem its kept sliding off the splined shaft and jamming the gears , so I took it out a welded it to the end of the shaft and ground back the weld . and refitted it, every thing works fine now. yours anna j