I'm pretty sure I know the answer to this, but I'd appreciate any advice from the experts. 1973 850 with 8300 miles. Picked it up last year and had a Brit bike/auto guy work on it over the winter. I've got Tri-Spark and Amal Premiers on it and it's running really sweet. My issue is that it's missing shifts, particularly 2nd to 3rd. I probably get 50% of the shifts in, the others hit a false neutral. Another stab down and I'm in 4th. I find if I stab the shift a bit towards the middle of the bike instead of straight down I'll have a higher probability of hitting the shift. Gearbox was not touched over the winter. Is this my layshaft bearing telling me it needs to be replaced? Pics here: https://plus.google.com/photos/10016038 ... banner=pwa
Shifting issue…>
- Thread starter ommief
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ommief said:
Have you tried varied amounts of force/velocity on the shifter? "Stab" could be slang, kinda suggests rapid. How's the clutch feel?
Not suggesting you're doing it wrong, but rather, what modified technique it responds to, if any, many times is indicative of the problem with the mechanism.
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The layshaft sign of imminent failure is the kickstart lever swinging backwards as you accelerate, your symptoms are connected to the indexing and first item to check is the thin spring on the ratchet inside the outer cover. If you need to go further into the box then replace any ball bearing with a steel cage no matter how good it looks, replace with roller with a E or a ball with polyamide cage.
Missed shifts could be caused by many variables--incorrect indexing of the shift quadrant--worn camplate--bent shafts--worn bushings--trashed bearings--worn or broken gears--worn or broken shift forks--incorrectly installed or broken ratchet spring--too-tight primary chain--and so on.
Someone familiar with Norton gearboxes should be able to pull things apart and eliminate some of the suspects--the problem might be right there in the outer cover--best of luck
Tim Kraakevik
kraakevik@voyager.net
Someone familiar with Norton gearboxes should be able to pull things apart and eliminate some of the suspects--the problem might be right there in the outer cover--best of luck
Tim Kraakevik
kraakevik@voyager.net
There is a lot of movement going on between 2nd and 3rd. I would think there are worn bushings some where in there. Drain the warmed lube and look for gold glitter. Although there is usually some presant, yours may have an excessive amount or more than usual.
I like to shift as though I was driving an old pickup truck, alway being mindful of that sweet spot with the RPM's. If I am going to the races, I'll get a different gearbox. But for now I will be respectful of the poor thing. I will also use the brakes to stop and down shift when there is least resistance. Brake pads and clutch friction plates are easy, gearboxes are a little more detailed (but not all that hard either).
Many will not rule out the lay shaft bearing and of course when re-bushing will be the time to replace it and the other bearings.
I like to shift as though I was driving an old pickup truck, alway being mindful of that sweet spot with the RPM's. If I am going to the races, I'll get a different gearbox. But for now I will be respectful of the poor thing. I will also use the brakes to stop and down shift when there is least resistance. Brake pads and clutch friction plates are easy, gearboxes are a little more detailed (but not all that hard either).
Many will not rule out the lay shaft bearing and of course when re-bushing will be the time to replace it and the other bearings.
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ommief said:
What you've described could be the 04-0038 ratchet return spring in need of some adjustment (or replacement & adjustment) rather than a layshaft bearing problem.
http://www.oldbritts.com/gearbox_a.html
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Ugh, any or all at once of the above plus worn bushes allowing cogs to tip on shaft there by wearing down shifter dog faces to lack enough trust to fully engage. Check primary correct tension to remove that funny business from investigation equation before deciding how bad ya want it fixed. AMC's should one of sweetest thoughtless shifters ever sold. If, ugh, when into outer case guts, note the rust above oil level and consider paint over or thick grease for the next time in or maybe next mechanic relief. Pawl spring is above oil, I've had 2 of them rust enough to loose springy ness or shape from one ride to the next. I keep a spare around for luck. Its not the pawl spring gap amount so much as its legs parallel in pawl sweep area that matters most. They generally need some delicate fine tuning when new.
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