1961 A10 Back Wheel Re-assembly

[AWJD]

I'm in the process of trying to re-assemble my rear wheel hub but I am having difficulty understanding what goes between the distance piece and the right-hand spindle and its bearing. With it assembled, I have the order of a 1/8" gap between these components.

At the moment, there doesn't seem to be anything holding the retainer (42-6105) in place and I seem to be missing the cap (42-6328).

I would be very grateful if someone could explain what I'm missing from the assembly and what form the cap takes because its difficult to understand from the parts book.

[1660bob]

Hi, your description is not too clear, its hard to identify exactly what you mean.By "right hand spindle" I would take that as the main, long spindle 42-6320, as right and left components on a motorcycle are generally referred to from the point of view of a seated rider.
By right hand spindle, I assume you mean the LEFT hand, short, spindle 42-6325? If this is the case, I think I can help. I do not think you have anything missing, and I agree the parts book is a little confusing, but bear with me, bit long winded.
Firstly,the "cap" 42-6328 is nothing to do with the short spindle or its bearing, it is simply drawn near to them in the parts book, but it is a knock in tin ring/cup that fits inside the main hub casting as a grease retainer and centraliser for the main, long spacer 42-6323-you can see it if you look inside the main hub casting from the sprocket end,between the four studs.
 Thats simple enough, the next bit is harder to grasp, and I feel you are puzzled, just as I was when i first looked at this assembly! The BSA rear hub is not entirely logical in its design-I think its a bit of a dogs dinner at the sprocket bearing end. There is meant to be a gap between the inner race of the sprocket bearing (89-3022)and the shoulder on the innermost end of the short spindle 42-6325. This bearing is a press fit into the sprocket, and is pressed in right up to the shoulder in the sprocket bore. Once in place, the rather flimsy tin cup"retainer" 42-6105 is knocked into the sprocket bore so the bearing is retained  both sides. 42-6105 should be a tight knock fit into the sprocket, if loose-new one needed, it is retained simply by its tight fit (see-I said dogs dinner!).- easy so far.
The short spindle 42-6325 is then tapped (may slide in loosely anyway due to wear)into the bearing through the middle of 6105, but there is no need to tap it in all the way to the shoulder  on 6325, you could do, but its pointless. Now,we fix the sprocket assembly to the swingarm  via spacer 42-6324, and washer/nut 6078/6077. Spindle 42-6325 is now rigidly held to swingarm .When the wheel is then fitted to the motorcycle, and the main spindle 42-6320 tightened up, the final job is to replace the four sprocket nuts and tighten the sprocket onto the main hub casting.When you tighten these four nuts,the sprocket bearing inner race will be forced to move along the short spindle 6325 slightly, to find its own natural place, according to manufacturing tolerances in the fit between the sprocket and hub faces. If there was a spacer or circlip on 6325(the one you think is "missing")it would stop the bearing inner from sliding to this natural place and strain the bearing as the four sprocket nuts were tightened up. In short, this arrangement (with your 1/8 "gap")allows the sprocket bearing to "float" a little along 6325, perhaps to allow for to expansion etc if the brake drum gets hot (ha ha!)
 Hope this explains it- `least that`s how i understand things! Best Regards, Bob C

[AWJD]

Thanks for your reply. It was a while ago  that I re-assembled the back wheel on my Golden Flash - in the end I must have sorted out the problem but can't remember exactly how. I think part of the confusion was over the location of the cap (42-6328) which, of course, does not form of the line up the components on the 2 spindles. I thought I was missing this part until I realised that it was already pressed into the hub tunnel.

The other part of the confusion was over the role of the retainer (42-6105) which did not seem to 'contain' anything. If memory serves me correctly, the RH bearing is held firmly in place against the shoulder inside the chain wheel when the RH wheel nut is tightened. I think the container is there solely to retain grease and keep the dust out of the bearing when the chain wheel is unbolted from the rest of the wheel. I don't think its there to keep the bearing in place because its too flimsy and there's nothing on the inside like a shoulder to limit its movement.

I suspect that when I tried to fit the wheel into frame, the 1/8" gap in the line-up made the assembly too wide to fit. I must then have found that the LH bearing was not seated properly and just needed pressing in a little further.

[1660bob]

I think you still haven`t grasped it . If you look in the proper BSA A10 Instruction Manual, (handbook) there is a very good C/S drawing of the late rear hub,  page 36-37 depending on which edition of the handbook you look at. It clearly shows that 6105 does indeed knock into the sprocket until it stops against the outer race of the bearing, "trapping" the bearing against the shoulder in the sprocket .Thus that bearing cannot move in relation to the sprocket itself.Yes I agree,6105 is flimsy, but that`s why it must be tight in the sprocket- if not tight, its bin or Loctite! You can also see from the drawing that there is a substantial gap between the bearing inner race, and the innermost shoulder of the short spindle 6325-about 1/8 to 3/16". If you look at your short spindle next time you have it apart, you will see the mark on the spindle surface where the bearing actually sits when all is assembled, its nowhere near the shoulder. Tightening up the nut on the spindle simply locks the spindle to the swing arm, it has no effect at all on the bearing, in fact, if  6325 is worn and loose in the bearing, with the spindle nut tight,you could slide the whole sprocket and bearing back and forth along the spindle until the bearing hits the shoulder on 6325 and stops (this with the wheel NOT fitted of course) Keep studying it and the penny will drop! Best Regards, Bob.

[AWJD]

1660bob.

I've just had to revisit this issue and looked up the hub diagram in the A10m Instruction Manual. I understand what you were saying in your last reply but the diagram does not appear to show the gap - in fact the larger shoulder on the fixed axle appears to be butting up against the bearing inner race. Was the diagram in your Instruction Manual different or did I simply misunderstand you.

Cheers,
Arthur

[RichardL]

Reading all this with moderate interest, I can't see where the cross-section AW3D has posted equates to the exploded view shown by Draganfly, here: http://draganfly.co.uk/index.php/bsa/bsa/a710--b3133--c101112--m202133/category/925-13-7-inch-rear-full-width-cast-iron-1958-63-a-b

Am I missing something?

Richard L.

[RichardL]

AW3D,

I think I figured it out. You say you have a '61, which would have a full-width iron hub, but the cross-section you're showing is for a '56-'57 aluminum hub, as shown here: http://draganfly.co.uk/images/shop/b3/21/12.gif

Not that I can give you as thorough a description of assembly as 1660bob, but I am curious, which hub you actually have?

Richard L.

[AWJD]

I did this in haste and must have picked up the instruction manual and diagram from the wrong year for the A10. I've since seen the correct diagram which shows the correct configuration for the fixed axle in my hub. Apologies for the confusion.