Gearbox hard shift after rebuild

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998cc

998cc

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Finished up the gearbox Thursday morning and road tested. Leaving the driveway and onto the road, could not get second gear then overran/skipped into third. Shut down and went through gears by rocking the bike. Back on the road, better this time. Put about 8 miles on her varying speeds up to about 50 MPH and copious gear shifting. Shifting did improve somewhat.

Scope of project:
Gearbox:
New Andover kit. Bearings and bushings/bushes except the gearshift bush in the inner cover. (Roller layshaft bearing shimmed to .007" end float.)
New 1st gear pinion set and 2nd gear pinion set. New sleeve gear.
New outer cover in lieu of machining for oil seals at Gearshift and K/S shafts.
Other than transferring the shift ratchet to the new cover, I left the assembly as is. The clearance at the ratchet spring looks good.
New gaskets from Andover kit.
Lucas Oil 75-90 in the gearbox.

Primary chain case:

New inner primary case.
5W 30 oil in primary case.
I did not adjust the primary chain, but it seems tight.

Any thoughts and/or direction is appreciated.

Thanks!

~998cc
 
primary chain too tight first suspect


After a recent trans rebuild I had binding, turned out to be the pressed in bushing in the replacement first gear sticking out too much taking up all the shaft end float. Filed it down and was good to go
 
998cc said:
Other than transferring the shift ratchet to the new cover, I left the assembly as is. The clearance at the ratchet spring looks good.


Any thoughts and/or direction is appreciated.

Thanks!

~998cc
Click to expand...

Check the ratchet spring again it can be a right sod the set up and check to see if it the correct way up.

Dave
 
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cash said:
Check the ratchet spring again it can be a right sod the set up and check to see if it the correct way up.

Dave
Click to expand...


Dave. I am hoping that is it. Heading back to the garage to take a little tension out of the primary chain per Jimbo's post and take a quick ride. Though the primary went together without adjustment, it dawned on me that the old sleeve gear bushings were worn; the new sleeve gear and bushes must have tightened the chain. If no better, the outer cover comes off. Might put the old one back on in case the new one has a slight error in machining.

Thank you!
Regards,
~998cc
 
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Gearbox hard shift after rebuild
jimbo said:
primary chain too tight first suspect


After a recent trans rebuild I had binding, turned out to be the pressed in bushing in the replacement first gear sticking out too much taking up all the shaft end float. Filed it down and was good to go
Click to expand...

Opened up the gearbox to check the ratchet spring. As a matter of course, always check the drained oil in the sunshine. The dreaded shimmering metallic cloud in the oil. The gears/pinions all out revealed exactly what Jimbo describes above; the bush in the new 1st gear (lay) protrudes and wears against the K/S shaft.

The source of the metal flakes is the shift fork for the new 2nd gear lay. I am baffled as to the cause.


~998cc
 
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with the bush against the kick start bush it will push 1st towards the 2nd lay and that will force 2nd lay against the shift fork and cause rapid wear. if that is the side of the wear on the fork. if not than you could have an issue with no under cut on the 3rd lay or that side of 2nd lay. which side of the fork has the wear?

998cc said:
the bush in the new 1st gear (lay) protrudes and wears against the K/S shaft.

The source of the metal flakes is the shift fork for the new 2nd gear lay. I am baffled as to the cause.

~998cc
Click to expand...
 
Might the tight shifting be just a bedding in situation? My GB felt a lot tighterr right after I did the rebuild...pretty much what you've done except went with phenolic ball bearing for layshaft as is Mick Hemmings recommendation. And I did not replace any pinions, just bushes/seals/springs/pawl and the clutch lifter rolloer was flat spotted so did that too. Now, after some 500 miles. shifting it pretty much back to where it was last season (bike had 11000 miles on it at that point).
 
Tornado. The metal lost was more than just parts getting cozy with each other. This was during about 22 miles of riding.

Thumbnail photos of the shift fork.

Gearbox hard shift after rebuild Gearbox hard shift after rebuild

~998cc
 
how was the fit of 2nd lay on the shaft? it should be a loose sliding fit. if it was tight on the shaft it would keep pressure on the fork. also look at the dogs on 2nd lay, it should have some under cut on 3rd side and that is the side with the most wear but i am leaning more to the gear to tight on the shaft with wear on both sides of the fork even though the 1st side is less.
 
bill said:
how was the fit of 2nd lay on the shaft? it should be a loose sliding fit. if it was tight on the shaft it would keep pressure on the fork. also look at the dogs on 2nd lay, it should have some under cut on 3rd side and that is the side with the most wear but i am leaning more to the gear to tight on the shaft with wear on both sides of the fork even though the 1st side is less.
Click to expand...

Hello Bill.
Fits for all pinions/gears are very nice. As a last ditch effort, I put the old 2nd lay gear back in, dressed the worn fork and took out a 10 thou layshaft shim. Lubed everything during assembly and took a ride. Shifting was very smooth for about three miles then went bad again.

Wishing I'd have just replaced the old lay bearing with a good ball bearing and closed 'er up.

~998cc
 
i am pretty much out of answers for now. if you was close i would say to bring it by. i am in Ne Tn.
 
bill said:
i am pretty much out of answers for now. if you was close i would say to bring it by. i am in Ne Tn.
Click to expand...

Thanks Bill. There is a shop not for from me that does Norton work. That my be the best option.

Regards,

~998cc
 
Following up on this thread:
First off, thanks to the group for all the responses. :)

Going almost back to square one with the gearbox; the new Andover 1st and 2nd gear pairs were removed but left the new sleeve gear in. Re-fitted the worn original 1st and 2nd pairs and now have .103” end float at the layshaft instead of .074” with Andover pinions. I know the experts recommend .005” to .010” layshaft end float using the roller bearing; that seems a bit tight to me, so I shimmed layshaft to .020”. Took a 30-plus mile ride a few minutes ago, and shifting through the gears is now back to normal.

Not sure where to go from here as the 1st and 2nd pinions are worn and need replacement. :confused:

Bike is on the road, tho! :)

Regards,

~998cc
 
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Most of the things on Nortons need a bit of end float and some over shim them for very little end float at all, myself just leave things they were, replace things that need replacing but as for shimming I leave it well alone and after 43 years its still going with out any shims in my motor or gearbox, layshaft bearing replaced way back in the late 70s and 4 KS pawls and one KS shaft and KS gear is all thats been replaced in all that time. have a bit of end play but my gearbox works great has light shifts and just a click to find neutral.
So if it was ok before you put the shims in I say that would be your problem by over shimming and making things tight inside.

Ashley
 
When I did mine with new first and second I had to hit both mating service with Emory.
 
ashman said:
Most of the things on Nortons need a bit of end float and some over shim them for very little end float at all, myself just leave things they were, replace things that need replacing but as for shimming I leave it well alone and after 43 years its still going with out any shims in my motor or gearbox, layshaft bearing replaced way back in the late 70s and 4 KS pawls and one KS shaft and KS gear is all thats been replaced in all that time. have a bit of end play but my gearbox works great has light shifts and just a click to find neutral.
So if it was ok before you put the shims in I say that would be your problem by over shimming and making things tight inside.

Ashley
Click to expand...


Thanks Ashley.
I'll try again with the new pinions. Ordered new shift forks and fork shaft since all are worn. With the original pinions, it does work, but without shims, the gap is wide at .103". It does shift well at .020" shimmed, so I will shim to .020+ with the new pinions and then test. Don't know if it is possible, but with the next build, I'll try to determine if the shift forks are binding prior to starting or taking the bike on the road. In the meantime, good riding weather here.

Thanks again.
Regards,
~998cc

Gearbox hard shift after rebuild
 
Thats a great pic both classic bikes together, but there be more Commandos around.

Ashley
 
ashman said:
Thats a great pic both classic bikes together, but there be more Commandos around.

Ashley
Click to expand...
Yes there are! Commandos are my favorite of all Brit Iron, but the wife would change the locks on the doors if I came home with another one! Rolled these two out but left the Bonneville and the Tiger Cub in the garage.

~998cc
 
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