Gearchange Problem Solved

After completely rebuilding the bike over the last 2 years, it would start and run ok but I couldn't ride it. It would go into first but then the gearlever seemed to be attached to nothing in the box.
With the cover removed I could select all gears nicely by moving the quadrant with a bar in the roller pin.
With the cover on I could select gears by moving the lever by hand without the engine running.
But trying to ride it was an exercise in frustration. After taking the cover off several times and fiddling with the pawl spring I had no answers. It's such a simple mechanism, but it stumped me.

Then I looked at it again today after being bogged down with work for 5 weeks.
I noticed that, after moving the ratchet plate, the concave face of the pawl drags hard against the edge of the plate. My guess was that it dragged the plate back, not enough to pull it out of the selected gear, but enough so that the pawl would not engage with the ratchet teeth on the next movement of the pedal, except to push it back into the gear it was already in.

So I bit the bullet and ground some 20 to 30 thou off the concave face of the pawl. The result: excellent gearshifts.

I don't know if I've just re-invented the wheel, but I haven't found this solution to bad gear selection elsewhere.



The last photo was supposed to show the drag marks on the (new) pawl, but my new fangled camera only wanted to focus on the background.

The photos were taken before grinding the pawl.

This rather raises the question of what might have changed. It's difficult to believe that previous owners could have lived with such a fault. Was the selector built from parts or with some new components ?

That's a good idea, and I'm glad it fixed your problem, but mine has always shifted beautifully stock.
For close up photos, try putting your camera into Macro mode.
Jaydee

I bought this bike in 1983 as a basket case and rebuilt it on a shoestring budget. Despite that, it always performed well in all regards until I mothballed it for over 20 years.
When I tried to put it back on the road, various problems arose such as refusal to run properly (carbs) and also erratic gearchanging, despite no changes being made to the gearbox.
So I stripped the bike and rebuilt it from the ground up on a better budget this time, including some new bearings, bushes and gears in the box AND a new selector pawl for good measure.
I held the old and new pawls together before fitting the new one: they seemed to be identical. No other parts of the selector mechanism were changed.

So when gear selection turned out to be MUCH worse than it ever was before, I was very disappointed to say the least.

Having found the problem, despite its genesis being a bit of a mystery, I thought I might share the solution. I have read posts on the forum about gear selection problems occurring occasionally, even though the AMC box is generally known as a sweet changer as mine was originally. It might help someone.

The hairpin spring has a correct orientation; installing it upside-down results in issues. Also, the thin spacer washer needs to be installed in the correct order with the other bits.

I think I see the cause of your problem. As paul pointed out, the large, thin washer has to be in the correct location. And it isn't, or at least it doesn't appear to be. The washer appears to be between the spring and the ratchet plate, but it is supposed to be between the outer cover and the pawl carrier assembly. As you have it, the pawl assembly is closer to the outer cover by the thickness of the washer, and the pawl rubs. If you install the washer in the correct location, it will move the pawl out from the cover by the thickness of the washer. I'll try to hunt up an illustration and post it.

My apologies in advance if I'm misinterpreting the position from the pictures you posted.

Ken

The thin washer is between the outer cover and the pawl carrier, even though it doesn't seem to be in the photo. Old Britts gearbox assembly notes and photos, especially the one with a cutaway outer cover, were very helpful in this regard.
I checked everything over and over before finally identifying the problem.
It looks like Ludwig has nailed it; my bike is a 1970.

Martin

Always a risk in trying to diagnose from pictures. No insult to your ability intended. You've clearly taken a lot of care to be sure it's all done properly.

Kudos to Ludwig. That's another bit of Norton arcane knowledge I hadn't heard before.

Ken

The other thing to look out for if you remove and refit the stop plate, it can foul on the bottom pin that the return spring locates onto if the two bolts are tightened without checking clearance of the stop plate. The holes in the stop plate allow a little bit of variety in the position as the bolts are a slightly loose fit in the holes.

ludwig said:

dave M said:

The other thing to look out for if you remove and refit the stop plate, it can foul on the bottom pin that the return spring locates onto if the two bolts are tightened without checking clearance of the stop plate. The holes in the stop plate allow a little bit of variety in the position as the bolts are a slightly loose fit in the holes.

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That's why , like I said , it is better to use the stop plates with the larger cutout .
(or make the cutout in the older stop plate bigger ..)

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Dave's suggestion is a trick I have used successfully in the past and it ties in with Ludwig's knowledge of the older stop plate.
This time though it didn't work. Nothing worked except for modifying the pawl to relieve the drag on the ratchet plate.
If anyone out there is experiencing the odd missed gear, it's something worth looking out for next time you take the outer cover off.
Pawls are cheap enough. Have a spare one handy and you can grind away happily knowing you have a backup plan.

My case was an extreme one. But I went from having no gearchange at all to reliable shifting just by grinding the pawl.

Martin

Norton owners who don't ride their bikes regularly often find that they turn nasty and take revenge on them . Any Australian will tell you, - you cannot trust a Pommie bastard.

acotrel said:

Norton owners who don't ride their bikes regularly often find that they turn nasty and take revenge on them . Any Australian will tell you, - you cannot trust a Pommie bastard.

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Oh yeah it took its revenge big time. I suppose I can't blame it though.

All I wanted to do was put it back on the road to celebrate its 40th birthday; that was in 2010. I think I'd better keep riding it from now on.

Cheers
Martin