replace layshaft bearing without removing main shaft

Got my bearing and gaskets on order from Angie (what a peach) and will dive into this next week. Bike only has about 6k actual miles on it so I expect that nothing other than the layshaft bearing will need replacing (and it is likely still in one piece but doing it anyhow). From what I read this is doable so I shall see. I have a good heat gun so I can heat the case to get the old bearing out. I plan on the freezer trick and hot case so the new will slip right in.

I tried searching for anyone else who did this without main shaft removal and never could really find anything but did see a comment that the bearing can be removed with the main ins situ.

I've had this bike restored now for 5 years and this is the only thing other than maintenance items I've had to dig in to. And it's not showing any symptoms but I figured I better get it done. There was one instance I read where it let loose without any real warning.

Mark Schmitz did his recently with great success and a bit of hilarity, under layshaft bearing failure.
Best of luck.
J

Thanks for the tip on that thread. I knew I had seen that somewhere but could not find it.

Looks pretty straight forward. Last trans I had apart was my 70 Triumph Tiger. That quadrant in that sucker gave me fits but got it sorted. Looks like I won't have to mess with that on this trans either. woo hoo.

I'm in the midst of this now. I was able to get the layshaft out no problem with mainshaft present following the instructions in the Norton Companion Workshop manual. See "Layshaft bearing Upgrade".

Once in there I decided to take a look at everything else so I took the primary side apart and pulled everything out of the gearbox. I found my mainshaft was bent (.007" TIR) and most of the bushes were either too loose or too tight (or chewed up). I am now in the process of replacing all the shaft bushes and the 3 bearings, along with the mainshaft. I already had a spare genuine mainshaft bought on sale when Domiracer was getting ready to go under. It has zero runout. The only drawback in doing it in this order is that once the guts are out of the gearbox, you need a way of holding the mainshaft to undo the nuts on the primary side. I bought the clutch holding tool from an Andover dealer - well worth it! The latest ones have a heavy duty handle bolted on which rests against the rear Iso nut nicely - a one person job.

I will be starting reassembly soon. I took all my bushes and shafts to a local auto racing machine shop and had them pressed in and reamed to fit. Most are very thin and I was worried that I'd crush them without proper mandrels, etc. I got them all back today (next day) all done for $65 cash - nothing broken - and I was happy with that.

I didn't mess with the quadrant. Don't unless you have to.

Russ

A extra 1/2 hour work and you can pull the whole gearbox down, I would do it this way to be sure your gearbox is fully rebuilt, be silly to just replace the layshaft bearing without doing the other bearings, then your gearbox will last a life time if looked after, its not a hard job to do, its best to be safe than sorry later on, do the complete job once and forget about it later, I replaced my bearing in my gearbox in 1979 when my layshaft failed, did a full rebuild and its still together to this day except I have replaced the kick start pawl 4 times since and the kick start gear once because where the kick start pawl sits in the gear was worn.

Ashley

ashman said:

A extra 1/2 hour work and you can pull the whole gearbox down, I would do it this way to be sure your gearbox is fully rebuilt, be silly to just replace the layshaft bearing without doing the other bearings, then your gearbox will last a life time if looked after, its not a hard job to do, its best to be safe than sorry later on, do the complete job once and forget about it later, I replaced my bearing in my gearbox in 1979 when my layshaft failed, did a full rebuild and its still together to this day except I have replaced the kick start pawl 4 times since and the kick start gear once because where the kick start pawl sits in the gear was worn.

Ashley

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I agree, and it's sort of a shame not to rebush the sleeve gear also. It's sort of critical. Easy to do and not too pricey. If you see any wear in there (gold dust), you can be sure alot of it is from the sleeve gear bushes.

pete.v said:

ashman said:

A extra 1/2 hour work and you can pull the whole gearbox down, I would do it this way to be sure your gearbox is fully rebuilt, be silly to just replace the layshaft bearing without doing the other bearings, then your gearbox will last a life time if looked after, its not a hard job to do, its best to be safe than sorry later on, do the complete job once and forget about it later, I replaced my bearing in my gearbox in 1979 when my layshaft failed, did a full rebuild and its still together to this day except I have replaced the kick start pawl 4 times since and the kick start gear once because where the kick start pawl sits in the gear was worn.

Ashley

Click to expand...

I agree, and it's sort of a shame not to rebush the sleeve gear also. It's sort of critical. Easy to do and not too pricey. If you see any wear in there (gold dust), you can be sure alot of it is from the sleeve gear bushes.

Click to expand...

To be fair it's a bit more than half an hour Ashley more like 1 1/2hr plus by the time you bugger about with clutch etc,inc refit time. but many have done it in situ and have had no probs. but I have to agree with Pete and your goodself and have always said pull the box and do the full job, plus you can take the camplate and quadrant bolts out and apply some copper grease cos those wee blighters can seize up tight.