Layshaft Bearing Question

I'm going in this winter so pray for me. Cover me Sarge!!!!!
I'm opening up my trans to address a kicker oring leak.
AMR will modify the outer case.
I have a kicker pawl that slips 1 tooth every 10 or so kicks of the kicker.
Not a big issue but while I'm in there might as well address.
While this far into it I might as well replace layshaft bearing to remove all potential failure issues
My question is can I replace the bearing while the case is still on the bike?
Can I place heat to the back of the case w/ a propane torch from inside the case
w/o creating other problems like melting the main shaft oil seal?
Clutch has no issues nor is there gear oil leaking into the primary.
I'd like to avoid digging into the primary side or creating an issue if possible.
Looking for the best way to attack it from those who have been there done that before.
I'd like to avoid the 1st timer mistakes if possible just once in life. :lol:
Thanks in advance ,
MarshalNorton

MarshalNorton said:

While this far into it I might as well replace layshaft bearing to remove all potential failure issues
My question is can I replace the bearing while the case is still on the bike?

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Yes.

MarshalNorton said:

Can I place heat to the back of the case w/ a propane torch from inside the case w/o creating other problems like melting the main shaft oil seal?

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If it still has a layshaft ball bearing, then the layshaft can be quite a tight fit in it, so you may not be able to get a torch in there easily if the layshaft won't come out, and the mainshaft will also be in the way if you don't want to remove the primary drive, but it's probably not impossible? If the ball bearing has already been changed to a roller, then the layshaft should pull straight out with the roller bearing inner race on its end?

I prefer to remove the primary drive and heat the case from the rear, as the heat from the torch can then be applied directly to the outside of the case in the area around the layshaft bearing. Once the case is hot enough, a tug on the end of the layshaft should release it, along with the ball bearing still on the end, and provided that only just enough heat is applied, then the mainshaft seal shouldn't be damaged.

I suggest you replace all the springs, and all parts of the kickstart ratchet pawl mechanism.

LAB,
Thank you for an easy to understand and simplified yet thorough explanation.
It looks like I'm going to end up taking apart the the primary side.
Glad to know I can do the job w/o messing w/ the main shaft or damaging the main oil seal w/ heating.
I was planing on taking your advise and rebuilding the kicker shaft w/ a new pawl, spring etc...
Also the racheting pawl springs in the outer case will be replaced.
I believe its going to be an orig factory bearing.
Bike was purchased from orig owner and he is no longer at address on title to ask him.
Bike had 8000 miles so doubt it was touched.
Looks like there is evidence that the lower end was apart and new pistons at some time in its life.
I recall combats had issues w/ crank bearings and piston crowns coming apart.
When I purchased the bike in 2004 I was not well versed in commandos so I didn't ask all the right questions
while I had the owner avail.
Well I'll share the experience when I start the tear down.
Any other tricks of the trade are most welcome :idea:
MarshalNorton

I think I'd probably want to change the layshaft 1st gear bush, and also have a layshaft T/S bush handy, just in case?

If you fit the roller bearing, then you may have to shim the layshaft if there's a bit too much end float?

I use the 'Hemmings' special ball bearing, but it's a matter of choice I suppose?

It should all be fairly straightforward, as the box internals are quite simple, so provided you note how it all comes apart, (just make sure layshaft 4th gear goes back in with the raised section against the bearing) then you shouldn't really have any problems.


Here's some useful gearbox info from the OldBritts tech.section.
http://www.oldbritts.com/gearbox_info.html
http://www.oldbritts.com/gearbox_d.html
http://www.oldbritts.com/gearbox_a.html

LAB,
Do I interpret correctly?
If I purchase a Hemmings preferred bearing than end float and shimming is not a concern?
Just install and go?
Thanks,
Marshal

MarshalNorton said:

Do I interpret correctly?
If I purchase a Hemmings preferred bearing than end float and shimming is not a concern?
Just install and go?

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I haven't found shimming to be necessary with the Hemmings bearing (perhaps our other members could say if they've found it necessary?) although I'd think the majority of our members use the roller bearing?

ludwig said:

When undoing the inner cover , you will find there is not much space around 4 of the 7 nuts .
Have a thinwall 1/4W socket ready .
Or , once removed , file them down to 13 mm ( maybe sacrilege to some ) , this will give you a welcome extra mm of space , plus you can use more common 13 mm sockets .

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I recently took delivery of some gearbox bits from RGM, including reduced hex stainless (shameless Bling Tart) nuts for the inner cover - definitely easier to access
Unfortunately I can't remember what size they are - possibly 1/2" AF.

B+Bogus said:

I recently took delivery of some gearbox bits from RGM, including reduced hex stainless (shameless Bling Tart) nuts for the inner cover - definitely easier to access
Unfortunately I can't remember what size they are - possibly 1/2" AF.

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My MkIII's inner cover nuts have smaller (3/16W) hexagons. Apparently they must be the ones Mick Hemmings remarks about in his NOC gearbox rebuild DVD that John Hudson said were used, but Mick reckons he's never seen!

Thanks for the responses everyone
The socket info will be helpful , I betterr check my socket set?
I know what to expect now.
I think I'll go w/ the Mick Hemming video and bearing to simplfy matters.
Can't have to much knowledge
Thanks,
Marshal

If you have the primary removed for access to the back of the gearbox, it isn't much more dificult to remove the gearbox and take it over to the workbench, strip the entire box and do a proper rebuild! You don't want to have to go back in there a second time. :wink:

I just finished this job. You could definitely do it in situ, but it's gonna be a lot easier to do with the gearbox out of the bike. I removed primary side, removed gearbox mounts and gearbox-frameplate to motor mounts, breather tube and the oil lines to the timing cover junction, plus the junction itself, PUT BIKE ON SIDESTAND (so that motor moves forward and doesn't obstruct lower cutout in gearbox frameplate), turn gearbox counterclockwise and wiggle her out. Put it back on the center stand and take the gearbox in to the workbench (a vise makes the job a LOT easier).

Honestly, getting the gearbox out adds a lot of work in terms of removing the primary side and various other bits, but I've got to think it'll be just as much work trying to work around the situation with the box in the frame. You also won't be able to change the main bearing and its oil seal nor the sleeve gear bushes, which are probably worth doing while you're in there.

I guess the compromise would be to remove the primary side but leave the box in place. Then you'd have a much better shot at the back side with your torch, and could do the main bearing/oil seal/sleeve gear bushes. But the additional work to get the box out at that point isn't all that much. It's also an opportunity to clean up some of those parts - gearbox and frame mounting bolts, etc. I cleaned with brake cleaner and WD-40, went over them with a wire brush in a Dremel, and put antiseize on the shafts and blue loctite on the threads. Felt a bit better about them afterwards. Placebo in effect!

Thanks for the additional responses.
Now I've heard what it takes from in frame vs outta frame rebuild.
Thanks to all
Marshal