First time going deep – Gear Box.

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SKF is a Swedish ball bearing manufacturer going since early 1900s. They now have factory all over the world. Both the British and the Germans used to send planes into Sweden durning WW 2 to collect bearings for their machines. . . . .
 

NickZ

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It took a bit of work, but I put the new sleeve gear bearing in this afternoon.
I see Mick Hemmings just drop the bearings in on the DVD. Much tighter fit here. Had to drift it in with a lot of tapping.
 
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You say that camplate, quadrant and plunger works ok. If no oil leak there, fine.
Usually, the only thing that happens when the clutch nut come off is that you can't disengage cluch. The chain keeps the cluch in place.
Yes, replacing 1st gear pair a good idea, since they transmit power in 1st, 2nd and 3rd.
The bush on layshaft 3rd should be free to rotate both on the shaft and in the gear. So I can't see why you can't get it out. But I've never seen any excessive wear if the bush sticks to the gear. Could be that shockproof oil.
Kick start shaft bush removal. The Mick Hemmings way of using a tap works for me.
You have not mentioned anything about the drive dogs on the gears. Could be problems with them if you or a PO, have had a habit of abusing them.
 

NickZ

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More heat needed.
Okay, next time I will try for more heat.
I had a heat gun on the inside of the case for about 15 minutes, and used my propane torch around the outside on the left side for maybe 2 minutes before I started putting the bearing in place.
 

NickZ

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You say that camplate, quadrant and plunger works ok. If no oil leak there, fine.
Usually, the only thing that happens when the clutch nut come off is that you can't disengage cluch. The chain keeps the cluch in place.
Yes, replacing 1st gear pair a good idea, since they transmit power in 1st, 2nd and 3rd.
The bush on layshaft 3rd should be free to rotate both on the shaft and in the gear. So I can't see why you can't get it out. But I've never seen any excessive wear if the bush sticks to the gear. Could be that shockproof oil.
Kick start shaft bush removal. The Mick Hemmings way of using a tap works for me.
You have not mentioned anything about the drive dogs on the gears. Could be problems with them if you or a PO, have had a habit of abusing them.
Great feedback! Thanks.

"The bush on layshaft 3rd should be free to rotate both on the shaft and in the gear. So I can't see why you can't get it out. But I've never seen any excessive wear if the bush sticks to the gear. Could be that shockproof oil."
The bush does rotate on both the shaft and the gear. I can't get it out because the 4th layshaft gear is still tight on the layshaft, keeping the 3rd from sliding off.
IMG_7997.JPG

I could use a puller to get the 4th off, but the risk / reward doesn't seem worth it to me, since the bush appears to be functioning well.
 

NickZ

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You have not mentioned anything about the drive dogs on the gears. Could be problems with them if you or a PO, have had a habit of abusing them.
Dogs looked ok to me. What do you think?
IMG_7994.JPG
IMG_7995.JPG
IMG_7996.JPG

This 3rd main shows a little wear on the leading edge, but that's the worst I found.

As I said at the beginning, I've never been here before, so I appreciate any perspective on what looks ok and what looks like a problem.
 
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Agree with grandpaul.
On bushes in gears. Usually they don't wear much, so if you don't feel any play, don't bother.
I've found used original gear bushes that had less play than new ones.o_O
On sleeve gear bushes. They wear most when the bike is standing still in neutral. Good race mechanics used to warm up the bike in high gear on a paddock stand.
 
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NickZ

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Agree with grandpaul.
On bushes in gears. Usually they don't wear much, so if you don't feel any play, don't bother.
I've found used original gear bushes that had less play than new ones.o_O
On sleeve gear bushes. They wear most when the bike is standing still in neutral. Good race mechanics used to warm up the bike in high gear on a paddock stand.
Good to know.
I did replace the sleeve gear bushes. (and 2nd main).
 
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Hey NickZ, love your "back fill" gear box rebuild project. I've rebuilt over a dozen AMC gear boxes and without exception find removing the trany case from the bike is the best way to accurately rebuild a AMC trany. once the case is removed and stripped you can heat the case in your oven (wives love this!) and the main and lay shaft bearing just fall out. You can then easily drop in the new bearings. question for you, did you have the main and lay shafts checked for straightness? The shafts are prone to bending from load and can be problematic if bent even a little like .005.
Good luck and let's keep the Nortons on the road!!
PS.-I did 135 miles on my '74 850 last Sunday. (I know, now I'm just bragging)
 

NickZ

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question for you, did you have the main and lay shafts checked for straightness? The shafts are prone to bending from load and can be problematic if bent even a little like .005.

No, and I just put everything back in :-(
 

NickZ

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No worries, check it now (in situ) with a dial guage...
Well, that's good news.
I plan to measure end float, but I'm not exactly sure how to measure shaft straightness. (I'm waiting for the jokes here.)
 

grandpaul

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Well, that's good news.
I plan to measure end float, but I'm not exactly sure how to measure shaft straightness. (I'm waiting for the jokes here.)
You just need a dial gauge. Set it up pointing at the shaft nose, zero it, then turn the shaft and see how much deflection you get.
 

NickZ

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Using the setup shown above, I measured right around 0.005" max movement on the main shaft when it turns.
Wouldn't that number include any sleeve gear bearing and/or bush play, in addition to any shaft deflection?

Trying to do this measurement on the layshaft seems not very useful since I can easily deflect it at least 0.050" worth of roller bearing play with my finger.
 

NickZ

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Another question I have is: How tight should the fit be between the mainshaft and sleeve gear bushes be?
The new bushes were initially very tight. I honed them out to where the shaft turns fairly easily inside the bushes, but turning the mainshaft brings the sleeve gear along with it if not held.
 
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Using the setup shown above, I measured right around 0.005" max movement on the main shaft when it turns.
Wouldn't that number include any sleeve gear bearing and/or bush play, in addition to any shaft deflection?

Trying to do this measurement on the layshaft seems not very useful since I can easily deflect it at least 0.050" worth of roller bearing play with my finger.
.050 of movement sounds like roller is worn out and needs replacing. At least the shaft is not bent.
 
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