Strange gearbox issues, too long dogs? UPDATE

Several years ago, I sent a Norton GB for a rebuild, as a shop were running a "sale" ... and I didn't want to mess with it. Over this COVID-19 lockdown, I replaced my 750 motor with an 850 motor I rebuilt 2 years ago, and installed the shop rebuilt GB.

Anyway, I have 90 miles on the bike. It is HARD to kick start (like it was "catching" on something) ... and the kick starter was going slightly backward when in first gear from a dead stop. What? This is a Norton specialist rebuilt GB, with roller layshaft bearing and shimmed! As far as running, it runs GREAT! Lot of torque AND smooth running AND shifting GB.

I measured .009" end play, so ... good? So then had to look inside. It appears 1st gear and 2nd layshaft gears were mating nice and tight; so tight that the dogs on 2nd gear layshaft --- were fouling on the kick start shaft !!! How could this be?

Please see atached pics. For comparison, I have a good used layshaft first gear beside the "worn" first gear layshaft. the worn gear even has a distinct wear mark groove where the kickstart shaft rubbed on it. Note that the bronze bushing on the "problem" gear has "crept" outboard to the kick start even.

Does my layshaft 2nd second gear have too long dogs???

How could this be? Experts please advise ...

nortriubuell said:

It appears 1st gear and 2nd layshaft gears were mating nice and tight; so tight that the dogs on 2nd gear layshaft --- were fouling on the kick start shaft !!! How could this be?

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I can't see any evidence of that in your photos. The layshaft 2nd gear dogs don't look scuffed and you haven't shown an end face pic of the kickstart shaft.

The kick start on the bottom, is the one that was in the GB. Shows minimal wear, but seems like it had to? One picture is a bunch of parts from a disassmbled GB, for parts wear comparison pics. Please note "wear marks" on "outboard" face of worn 2nd gear layshaft; where it contacts inboard face of layshaft 1st gear. I assume the wear marks are from extreme rubbing contact; as none of my other spare GB gears show this wear; or not as much anyway. Please advise ...

I have a 2nd gear with the same wear marks, not got the issues you have.

nortriubuell said:

Please note "wear marks" on "outboard" face of worn 2nd gear layshaft; where it contacts inboard face of layshaft 1st gear. I assume the wear marks are from extreme rubbing contact; as none of my other spare GB gears show this wear. Please advise ...

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During the 1st gear selection process the 2nd gear dogs rarely line up with the holes in 1st gear immediately but they slide against the face of 1st gear which is rotating until dogs and holes line up and the gear selects so the light marking on the face of 1st gear from the 2nd gear dogs you have looks normal enough.

Edit:
I think the other 1st gear does show similar marking but the 2nd gear with it doesn't have the high ratio identification groove so isn't as noticeable.

I an guessing but I think you need to file the bushing flush in the first gear .

looking at pictures 2 3 and 9 it looks like something has gotten between the1st and second lay gears outboard of the dogs.

My money is on the bush not being pressed in fully in the first place, which will affect the overall width and in turn relative position of the gear. In this case closer to the dogs.

I think the two 2nd gears are from different gear stacks, I thought different years had differences if mismatched could cause trouble. One has plain dogs and the other has dogs with lines. Fortunately I never had to assemble a gearbox from a giant basket of parts .

A bent shift fork could position the dogs too close to the gear.

I don't see anything unusual in the picture. The wear line on the back of the gear is normal.

If your running a belt drive and the belt is slightly too lose you will get a momentary lockup when you try to kickstart -as the belt tries to climb the next tooth.

UPDATE. Sure appreciate all the replies, especially from "comnoz" about the possible bent shift fork. (I never thought about that, though it "looks" ok.) Finished putting everything back together this morning and took it for a ride.

Anyway, I replaced 1st and 2nd layshaft gears, 1st and 2nd mainshaft gears, and the layshaft shifting fork --- with the parts from my other spare GB. I also replaced BOTH .015" SHIMS ... with ONE .020" shim.

Now ... it is NOT "snagging" when using the kick start, and the kick start does NOT go backwards when going in first gear from a dead stop!

It is shifting SMOOTH (Using valvoline max life full synthetic ATF, thanks comnoz!!!) ... and the bike is running great! I was wrong about the "dogs" maybe being too long; with a new electronic caliper, they measure the same as all my others. Guess I was just grabbing straws.