Gearbox happenings

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Looks like it was a good thing I decided to see what the inside of the Norton's gearbox looked like. I guess this means that it's time for a "kit".

I also found that the layshaft bearing is not of the new type. So roller bearing or new-style caged ball?

Gearbox happenings


Gearbox happenings
 
"I also found that the layshaft bearing is not of the new type. So roller bearing or new-style caged ball?"

There is a dumptruck load of discussion on this. Search "layshaft" and read till you fall asleep:D

Yes, good choice to tear down.
 
I'e seen that 1st gear bush cracked like that before. It's a thin delicate bush.
Never seen the mainshaft sleeve bush(s) do it though.
 
So, do these both just push out/in?
I don't see them listed in the parts lists.
Are they available for replacement?
 
If one lives daily on a Commando long they know to always have spare first bush on hand and praise the AMC design accident to reach it 'fairly' easy. Real Nortoneers don't bother till only fractured easy picking pieces left. Then just slip in new, button up, carry on. About the only bush that don't usually need dressing/reaming to fit either.
 
Case crakded.
Well, what a surprise!

Gearbox happenings


Local wisdom is clean the case thoroughly and Loktite the bearings in, and ride it.
 

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Very good news to see. Ready to rock n' roller on. ( Would just leave her in place , as it is a tight enough heat/cold interference fit already to not need to heat case and drop out the bearing again ). Hopefully that is just a ding mark to the shell in between the 2 bearing bores. No biggie even if it is a crack unless aggressive racing in the future. Good news.
 
So I pushed the new bushings into the 4th-main gear sleeve and they are too tight to slip onto the main gear shaft. This implies boring or reaming.

The main shaft measures 0.81"5. The closest reamer is 13/16 which is 0.825". 0.010 bushing clearance seems like a lot.

Comments on appropriate clearance for bushings in this gearbox?
 
How did you get the bushings into the sleeve gear ? When I rebuilt my box , I used a socket to knock out the old and knock in the new ones ( frozen). But they got tougher to fit inside the gear to the end of the tappings . So the final 2 taps were tight ones and I think this caused the final bush to "flare" inwards a slight bit, my fingernail snagged on it to prove my suspicion. Because the mainshaft would not enter at that end ,but would on the other that was not tapped. So this could be it. I dressed the flared thin snag with a round file and the mainshaft had it's sliding fit just fine. Up to you but check.
 
How did you get the bushings into the sleeve gear ? When I rebuilt my box , I used a socket to knock out the old and knock in the new ones ( frozen). But they got tougher to fit inside the gear to the end of the tappings . So the final 2 taps were tight ones and I think this caused the final bush to "flare" inwards a slight bit, my fingernail snagged on it to prove my suspicion. Because the mainshaft would not enter at that end ,but would on the other that was not tapped. So this could be it. I dressed the flared thin snag with a round file and the mainshaft had it's sliding fit just fine. Up to you but check.

I heated the gear and froze the bushing and then used a hand press to push in the bushings. This press holds the bushing/bearing square to the gear and a gentle pull on the lever smoothly slides the bushing into place without any hammering.

The bushing in the lay first gear pressed in the same way and fits the shaft.



Gearbox happenings


Normal clearance please.
 
Some bushings slide in and fit on the shafts right off. Some need a little persuasion.

Gearbox happenings


Some need a little help to remove.

Gearbox happenings


Almost ready to start the reassembly process.

New bearings and bushings, seals and o-rings, shifter pawl spring, kickstarter pawl, clutch release arm, and gaskets and I think we might be ready to go.
 
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Brian,
You could have just turned in an old tap into the Kick start bush and turn it in the bronze bush about 6-8 revs take the assembly with tap and clamp the tap in a soft jaw vice and wack the kick start shaft with a hide mallet to drift it out. Then use the lay-shaft to push the new bush back in. as per Hemmings video. But you have a lathe and why not use it. Looks like you did it a school. Lockers in the background. How did the kick start pawl look? YMMV
Cheers,
Tom
 
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So I pushed the new bushings into the 4th-main gear sleeve and they are too tight to slip onto the main gear shaft. This implies boring or reaming.

The main shaft measures 0.81"5. The closest reamer is 13/16 which is 0.825". 0.010 bushing clearance seems like a lot.

Comments on appropriate clearance for bushings in this gearbox?
normally they shouldn't need to be reamed.
T
 
Brian,
You could have just turned in an old tap into the Kick start bush and turn it in the bronze bush about 6-8 revs take the assembly with tap and clamp the tap in a soft jaw vice and wack the kick start shaft with a hide mallet to drift it out. Then use the lay-shaft to push the new bush back in. as per Hemmings video. But you have a lathe and why not use it. Looks like you did it a school. Lockers in the background. How did the kick start pawl look? YMMV
Cheers,
Tom
I have a friend who teaches at the local Tech school, so I get help from him for delicate work although I have a lathe at home. It's a bit of a trick to make sure you bore the bushing exactly straight down the bore of the part. With gears it's critical.

Measurement showed that the output shaft's spline diameter was 0.001" larger than the bushing running surface and the newly bushed 4th gear shaft wouldn't clear. So we took 0.0015" off the bushing, getting it to pass the splines and that left us with 0.0025 bushing clearance on the running surface. That's nominal.

The kickstart pawl was notched a little so it was replaced. The shift pawl spring was worn at the coil so it was also replaced along with all the bearings, bushings, and seals. The main shaft bearing was worn out, while the others seemed ok and the gear teeth were good.
 
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