Flogged out mainshaft Na/numbered gearbox temporary fix

dilbery · Dec 15, 2020

Have used na /numbered gearbox shell for temporary fix on 850 mainshaft bearing in case flogged out case not bad ,bearing press fit with hand maybe a later solution.Seams to be stiff through shift and sometimes get neutral between 3/4th tightening spindle bolts seams to make matters worse all new bushes new main and layshaft ,new bearings problem may have started with new mainshaft replaced it first
That was all I wanted to do until sleeve gear dropped out.using pry bar outer cover off still renigs a little between 3/4th finds a neautral not all the time oiled up and rotating by hand with outer cover on needs a jiggle on gearshift to select gears , not all the time sometimes fine but a little stiff have pulled apart so many times looking for problem can do in dark , am I chasing my tail is it all the new parts am inclined to put in bike and run, frustrating chewing up all my good spares to problem solve never had this problem before ,how tight spindle bolts?seems to operate the same with small mainshaft nut undone or tight hope it’s not the case another I don’t have any way of checking it ? Thanks

Time Warp · Dec 16, 2020

You are having a bad run.
I would say any new parts need work out of the packets (I probably had a 1/2 hour just in the bushed second gear alone to get them to like each other)

These box's should bench check click through easy with the detent plunger backed off.
They of course can crack between the D/S bearing bores as the interference fit on the output bearing is hit and miss at best (To much and crack it will eventually)

Time Warp · Dec 16, 2020

dilbery said:
Have used na /numbered gearbox shell for temporary fix on 850 mainshaft bearing in case flogged out case not bad ,bearing press fit with hand maybe a later solution.Seams to be stiff through shift and sometimes get neutral between 3/4th tightening spindle bolts seams to make matters worse all new bushes new main and layshaft ,new bearings problem may have started with new mainshaft replaced it first
That was all I wanted to do until sleeve gear dropped out.using pry bar outer cover off still renigs a little between 3/4th finds a neautral not all the time oiled up and rotating by hand with outer cover on needs a jiggle on gearshift to select gears , not all the time sometimes fine but a little stiff have pulled apart so many times looking for problem can do in dark , am I chasing my tail is it all the new parts am inclined to put in bike and run, frustrating chewing up all my good spares to problem solve never had this problem before ,how tight spindle bolts?seems to operate the same with small mainshaft nut undone or tight hope it’s not the case another I don’t have any way of checking it ? Thanks

Does that mean a pre Commando case.

I would not expect any of the bearings on the D/S to be a push fit by hand unless the case is heated (non cracked)
On a cracked case the output bearing even with heat can be a press fit (not by hand) but that pretty much guarantees the layshaft bearing will be a drop in fit until cooled then Loctite # 290

With the fasteners that hold the inner cover to the case, bind would be odd, the layshaft overall would normally have some kind of axial clearance and the output shaft when pulled up to the T/S bearing would have clearance to the sleeve gear (as long as the 2nd gear bush is seated nicely otherwise 1st might push it up tight on the first shoulder.

Selection should be straight forward and you should be able to get slight over shift beyond the cam plate detents which should indicate clearance at full dog engagements (no over shift bind) (With the detent plunger backed off until the cam/quadrant can be cycled easily by hand or with a rod in the roller by hand)

I would regard the box as case selection (no external shift mechanism ( crisp shift, rotating by hand with positive detent stops)
I would then regard the external shift mechanism/ratchet as a separate entity that needs to be tuned to replicate the previous selection without excessive under or over shift (one can be good, the other not so much) so would get the interval selection verified first, certainly with no bind.

On a complete new box internals I could see hours of deburring and fettling.

dilbery · Dec 17, 2020

Time Warp said:
Does that mean a pre Commando case.

I would not expect any of the bearings on the D/S to be a push fit by hand unless the case is heated (non cracked)
On a cracked case the output bearing even with heat can be a press fit (not by hand) but that pretty much guarantees the layshaft bearing will be a drop in fit until cooled then Loctite # 290

With the fasteners that hold the inner cover to the case, bind would be odd, the layshaft overall would normally have some kind of axial clearance and the output shaft when pulled up to the T/S bearing would have clearance to the sleeve gear (as long as the 2nd gear bush is seated nicely otherwise 1st might push it up tight on the first shoulder.

Selection should be straight forward and you should be able to get slight over shift beyond the cam plate detents which should indicate clearance at full dog engagements (no over shift bind) (With the detent plunger backed off until the cam/quadrant can be cycled easily by hand or with a rod in the roller by hand)

I would regard the box as case selection (no external shift mechanism ( crisp shift, rotating by hand with positive detent stops)
I would then regard the external shift mechanism/ratchet as a separate entity that needs to be tuned to replicate the previous selection without excessive under or over shift (one can be good, the other not so much) so would get the interval selection verified first, certainly with no bind.

On a complete new box internals I could see hours of deburring and fettling.

H

dilbery · Dec 17, 2020

dilbery said:
H

Hello time warp my mechanical skills are a little better than my computer . Yes I used a pre commando or early? box to replace my original no crack between bearing houses in either the original was working fine but needed new mainshaft discovered loose bearing so replaced case ,mainshaft and bushes problems seemed to expand from there adding more new parts as I went(ALL bushes,main and layshaft,camplate and quadrant dreading the idea of going back in there lm thinking some issue with mainshaft it is new and using all my A’s new run in parts I replaced , 12000 miles on them hardly ran in have another mainshaft in good condition I will check for straightness and may be use.reassemble and check stage by stage a good suggestion. Having a rest on this one for a few days saving what’s left of my brain for new cam dilema (checkout cam thread)and loose intermediate gear spindle in case will get to spinning main on crank eventually

RoadScholar · Dec 18, 2020

New shafts that I worked with last month were straight enough, but the spline sections had some dings and the edges of the splines were sharp enough to cut a roast; the sliding gears didn't. I had to smooth the dings and radius the edges of the splines before the gears agreed to join the team.

Best.

concours · Dec 18, 2020

dilbery said:
Have used na /numbered gearbox shell for temporary fix on 850 mainshaft bearing in case flogged out case not bad ,bearing press fit with hand maybe a later solution.Seams to be stiff through shift and sometimes get neutral between 3/4th tightening spindle bolts seams to make matters worse all new bushes new main and layshaft ,new bearings problem may have started with new mainshaft replaced it first
That was all I wanted to do until sleeve gear dropped out.using pry bar outer cover off still renigs a little between 3/4th finds a neautral not all the time oiled up and rotating by hand with outer cover on needs a jiggle on gearshift to select gears , not all the time sometimes fine but a little stiff have pulled apart so many times looking for problem can do in dark , am I chasing my tail is it all the new parts am inclined to put in bike and run, frustrating chewing up all my good spares to problem solve never had this problem before ,how tight spindle bolts?seems to operate the same with small mainshaft nut undone or tight hope it’s not the case another I don’t have any way of checking it ? Thanks

Some Andover Norton transmission parts quality escapes (2015)

I had the opportunity to repair my failed transmission (still working, but 2nd had a funny "thump, thump, thump" noise. Disassembly revealed a LOT of damage.... I set to work inspecting (the case, sleeve gear and first gear lay were the only usable moving parts) and ordering parts. When I...

www.accessnorton.com

Flogged out mainshaft Na/numbered gearbox temporary fix

dilbery

Time Warp

.......back to the 70's.

Time Warp

.......back to the 70's.

dilbery

dilbery

RoadScholar

concours

Some Andover Norton transmission parts quality escapes (2015)

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