Final drive sleeve bearing

[Steverat]

I bought a new bearing on the principle that the gearbox was apart anyway, so why not take the opportunity to renew it. Its a good brand and inexpensive too.

When it arrived I found it was sealed. Now I expect this bearing to benefit from the oil I'm going to put in the box, so I tried to remove one of the sealing plates, at least on the side facing the gearbox cavity. The little holes in the plate seem to invite levering off with a pin or needle. But they are too small to get one in far enough.

Shall I get brutal and go for the plate with a hammer and a pointy punch?

[Bsareg]

That looks more like a shielded bearing (zz) rather than sealed(rr)

[Steverat]

It was sold to me for the gearbox sleeve gear application

[Swarfcut]

  Steve, as Reg says this is a shielded rather than a true sealed bearing. Up to you if you want to remove the shield, it will take more than a pin, but a lot less than a hammer and punch.  Unless the original bearing is rusted, rough or damaged, the improvment by changing the bearing will be marginal.

  The outer cover on your box should help identify its model year. Original A7 rigid and early A10/A7 plunger boxes have no grease nipple on the clutch arm sleeve, nor do they have an external nut to secure the kickstart spring retaining bolt. The kickstart spring is a flat clock spring type.  The box may or may not have an oilseal behind the sprocket, very early boxes have a scroll on the sprocket instead.

 Swarfy.

[chaterlea25]

Hi All,
Quite a lot of modern bike gearboxes use sealed bearings, BMW and Guzzi for example
The seals in the bearings are designed to keep the grease inside, but not designed to keep oil from seeping into the bearing if you follow
Shielded bearings will allow oil into the bearing but not metallic particles of any great size
I have fitted quite  few RS bearings to BSA boxes usually leaving the outer seal in place and adding some grease between the bearing and original outer seal
I have also fitted sealed bearings to early gearboxes which did not have any sealing arrangements, it does help stem the loss of lube but not 100%

John

[Steverat]

Thanks for replies, I removed the shield on the cavity side of the bearing to give clear access for the gearbox oil. At least this way the bearing gets washed out continuously. I have cleared the grease out and found the cage is a bit rattly when holding the inner and spinning the outer journal. But there is no debris in it; turning it slowly it is really smooth. Would the rattle be clearance which closes up when the bearing is in its housing? Hopefully. Feeling a bit apprehensive about fitting it now - I'd like to avoid the hassle of stripping it back out again.

[berger]

I have not been to the pub, steverat it will be fine , but when you heat the case and put it in if you have had the bearing in the freezer DO NOT try and fit the sleeve gear until everything has cooled to your workshop temp, I have come across the slight problem of the sleeve gear not wanting to fit until everything is of the same temp which gives you chance to have extended tea and biccies  edit--- steverat you'd be rattling if a big fly sucked all your lube out and left you dry LOL

[Steverat]

Getting the sleeve gear all the way in proved to be a bit of a task, still not fully home. I know that because its standing too proud inside the box and I'm trying to get the rest of the cogs in! Spent most of the evening wondering why I can't get neutral when assembling the box and it turned out the dogs on the (?second?) cog stay in engagement with the sleeve gear even with the selectors in neutral. Will push it right in tomorrow when my friendly road haulage business next door opens. They have a mighty press.

I am a bit worried about pushing too hard, the edge of the teeth inside the box are flush with the mating cog on the layshaft, so maybe I shouldn't press it. But I cant ignore the missing neutral.

[duTch]

 I reckon it should just be a nice snug slide-in fit, I found that the inside ends of the spline where they taper out somehow distort, so have had to relieve them a bit with the Dremel  ....probably not so good to force it, as that may expend the inner bearing race a tad and cause other issues.....conversely, I had a hard time  *extracting* a sleeve gear from the bearing a while back...

NB; For explanations, the official terms (as per 'The Chart') for the gears is A, C, E, G on the Mainshaft and B, D, F, H on the Layshaft

 It's also worth a reminder about the importance of the Thrust Washer between 'F' & 'H' gears....

[Swarfcut]

 Steve...If you are still sure the sleeve gear needs a bit more of a push I would avoid putting it in a big press.  I would use a couple of plates, a tubular spacer that supports the inner race and a nice threaded bar or bolt. That way you have more control, no chance of damaging the casting and can get more of a feeling for any movement. It also avoids any side load on the balls and tracks. From experience  the sleeve gear can often be drawn through the bearing using the sprocket and retaining nut if you have something to engage in the sprocket nut slots.  Next stage of violence was supporting the inner race and smacking the sleeve gear into place in the bearing with a block of wood and a big hammer, I assume you have tried this already. The secret is supporting the inner race. If it really is that hard to get into place, something is wrong with the basic fit tolerance of the bearing inner race and sleeve gear.

  Have a close look at the witness marks on the layshaft fixed pinion gear teeth to get an idea of how they should end up in relation to the drive sleeve teeth.

 Swarfy

[Steverat]

Swarfy I used your idea and it worked, the sleeve gear went home and now I can find neutral. Managed to do a satisfactory trial assembly, with functioning gearchanges. Many thanks. Now I just have to pick the best cogs from my growing collection.

[Swarfcut]

 Steve... Well done. Which trick did you use?

    Here are a few things to check before you nail it back together for good.

     Make sure the gear selector forks move smoothly on their shaft and that there is no bow in the shaft. The outer edge of the camplate should be nice and smooth, an over tightened plunger will wear a groove. The tip of the plunger should move smoothly along the edge of the camplate.  With just the inner cover, selectors, camplate and selector fork shaft assembled, the camplate should rotate freely.  In the past I  have bought new camplates which were slightly too thick and pressed the selectors too tightly between the shaft and camplate, making all three  bind. This can only be properly checked with the camplate, selector forks, shaft and inner cover assembled.

 The plunger pressing on the camplate edge also has an influence on rotating the camplate as well as locating it for gear selection. The tension on the plunger spring is a compromise between easy gear selection and positive engagement.  So if the  plunger can not assist in rotating the camplate, because of  binding, a sticking plunger or too strong or weak spring adjustment you will get a situation where going up the box is OK, but it is reluctant to change down. This is because the camplate will not rotate freely enough under the influence of the plunger and spring to a position which allows the gearchange claw to engage positively on the single "teeth" on the back of the camplate, ready for the next  down change. In other words, the camplate is just out of reach of the claw.  Going up is usually fine, coming down is a bit hit and miss.  On my  thicker camplate,  facing a few thou off the back to restore some clearance and free rotation was an easy fix.

  The S/A box has a different of design of camplate and gearchange mechanism which overcomes this problem (maybe). The camplate teeth and intermediate arm are in constant mesh, which moves the problem of uncertain selection into the outer cover.

 Swarfy.

[Steverat]

Used the same threaded rod, washers and nuts which I had used  for the plunger assembly, together with a turned-down piece of scaffolding pole to accomodate the sleeve as it comes out.

Thanks for the other tips too. I shall take it slowly, waiting for some hopefully better cogs to arrive at the mo.

Steve