Layshaft bearing & sleeve gear bush job

I bought a new layshaft bearing about 2 years ago and decided to finally do the deed. My Combat has about 38K miles on it. I didn't remove the transmission from the bike and followed the procedure in the Norton Workshop Manual Companion by David (napanorton) - Thank You. Everything went fine. The layshaft stayed in place and I used a heat gun to get the back of the case up to around 200F. Right about when the gear oil started smoking, I was able to yank it out. Hot and slippery! The old bearing is an SKF with metal cage and seemed pretty good. I was able to lever it off the layshaft with two screwdrivers.

While I had the transmission apart I decided it would be a good idea to replace the sleeve gear bushings too. This meant disassembling the primary. Since this part of it was unplanned, it was not all that easy to loosen the nuts with no guts in the transmission. I made a hardwood wedge to jam the primary chain against the clutch drum and was able to get the rotor nut off but will now have to get a clutch locking tool to get the clutch nut off. This seems to be the only way to do it because the mainshaft and clutch center turn freely with nothing to grab onto.

Good thing I decided to go for the whole enchilada. The clutch drum has maybe about 1/8"-3/16" movement! (Moves with the mainshaft.) The transmission and clutch worked very well in this state! My list of parts is growing. It is recommended to replace the right side layshaft bush in the kickstart shaft too so I will do that. It is a little sloppy. My thin layshaft 1st gear bush had moved and was disintegrating. The brass pieces stayed inside the cavity of the kickstart shaft. Gears look great for the most part - a bit of wear on the inside of the layshaft first gear where the pawl catches but that's an expensive one! I plan to replace the kickstart pawl and pawl pin.

Will add more once I get it apart further. I'm off work this week and definitely having a lot more fun!

Russ

I just did mine, complete rebuild. If you have gone to that extent you should really renew all the bushes for piece of mind. Good luck.

I found some 1/4" thick ally cut offs at a shop in 1" squares to finger size rectangles that hook up in chain teeth to center case bolt post and between the inner/outter clutch spines/teeth. Check shaft tureens. Sleeve bushes need a spare in middle if short type or use the two longer kind to prevent bush wondering. Not bad Id to oil groove em too. Thin about where these bushes are and the single state of operation that may let oil weep back in. To remove the thick kicker layshaft bronze bush takes some special procedures from grinding it to break up and up or notching for puller or adapting a concert anchor wedge bolt. Insept the dog faces close as loose bushes cock em to wear out of square to spoil thoughtless shifting. Old time racers said no need of any gaskets which is how I've done mine after first gaskets ruined. Special oil seal and be sourced for KS weeps or fill in o-ring groove base with layer of foil, light grease shaft, apply smear of RTV shove together and let set up over night.

Thanks guys... This is one of those "one thing leads to another" projects. Typical for our Nortons! I should know by now... Get out the wallet and suck it up.

Russ

another tip, use MK3 sleeve gear bushings. they are longer so offer more support through the gear.

bill said:

another tip, use MK3 sleeve gear bushings. they are longer so offer more support through the gear.

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Mick Hemmings and many other Norton experts recommend the earlier shorter bush saying the small gap between the bushes helps to hold oil which is essential to help stop bushes wearing. So as with many other Commando issues there would seem to be no simple answer there.
I follow Micks advice as the extra 1/8 of inch in the middle of the two bushes would be of little real world benefit. The oil would be of more use I feel an the longer bushings will just stay in place better as they touch each other an have circlip at each end. So as I have no circlip grooves it loctite that helps hold mine.
Each to their own though you pay your money so make your own choice.

toppy said:

Mick Hemmings and many other Norton experts recommend the earlier shorter bush saying the small gap between the bushes helps to hold oil which is essential to help stop bushes wearing. So as with many other Commando issues there would seem to be no simple answer there.
I follow Micks advice as the extra 1/8 of inch in the middle of the two bushes would be of little real world benefit. The oil would be of more use I feel an the longer bushings will just stay in place better as they touch each other an have circlip at each end. So as I have no circlip grooves it loctite that helps hold mine.
Each to their own though you pay your money so make your own choice.

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I'm not too clear on this. It seems like there would be a fairly big gap between 2 short bushes -- because I've seen that some people suggest using 3 short bushes in there. Each short bush is .88" according to the Old Britts description. I understand the idea that a gap between bushings would be good to act as a little oil pooling area. It sounds like Norton was more trying to solve the problem of the bushes moving around by making them longer so they butted up inside and having the circlips hold them. Are the Mk3s better or worse as far as wear here? I guess that would resolve the question. I could see shortening the longer type a little bit to create say a 1/4" gap. You'd then have the better support and at least some oiling.

Hobot mentioned scrolling the inside of the bushes to allow oil to be transported to the inner area. Not sure how this is done. Seems like it would take some fancy machining.

You're right toppy - no simple answers.

Russ

The sleeve bushes are above resting oil level, so oil drains out and none gets in while sitting still. In lower 3 gears these surfaces spin to sling oil out and can't let any back in till not spinning which only occurs in 4th gear, so no lube can enter sleeve bushes till in 4th and then only what can weep in the tiny gaps from splash and drain down. For the sleeve bushes to support shaft well they need to be near its ends but the short bushes can wonder to together as a center pivot for shaft wobble unless an extra short 'and worn' bush used as a middle spacer. The two longer bushes upgrade makes sense to me but makes oil entry even more an issue. Oil grooving bushes is low tech hand tool dremal level skill as only need to relieve a crude and fairly shallow groove that makes one ~360' spiral in bush length but do not let the groove go all the way to bush end on the outer DS bush as there is no seal there to stop oil from being pushed to outside. Ms Peel was only able to out accelerate potent moderns with her tallish gear ratio by allowing staying in 1st to almost 60 and 2nd to almost 90 mph/7500ish rpm, which in the elevated contests in Ozark Mt's meant ~20 minutes ~20 miles WOT hi rpm hardly ever in 4th, to see how fast bush/shaft interfaces can turn the little oil flow layer into carbonized diamond dust+ steel+ bronze ceramic hard grinding compound. After grooving 3 bushes and using ATF Peel's bushes stayed funcitonal way longer. On normal sanely run Trixie Combat with ordinary gear lube i get out of lower gears soon as i can for last 4-5 years 10K miles and just got a peek in to see nil detectable wear on 1st to sleeve bushes so will continue that habit after i fix the ks ratchet hang up. I can detect less drag with ATF in Peel but don't care in factory Trixie as she gets left behind by eager moderns in 1/2 mile or longer straights and any twisties d/t only Combat power and un-tamed isolastics but just enjoy its quaint old fashioned though smooth Harley like flight envelope. Trixie pulls harder than my SV650 but only after 90 mph which is just too much strain for it to do that much in 4th.