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Rear hub bearing retaining ring/speedo drive ring

Submitted by tony_wood on Thu, 03/09/2020
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Heavy Twins

Hi. Today I fitted the bearings into the rear hub of my 1960 Dommie 99 project. The right-hand one (single row bearing) is fully butted up against the step inside the hub - that’s good. However, the the flange on the bearing retaining ring/speedo drive ring doesn’t screw down fully against the hub. The ring is fully tightened (thanks to the AN peg spanner - great bit of kit) but the flange on the lock ring doesn’t touch the hub - there’s a gap of about 1mm. It’s exactly the same with the old (original, but damaged) locking ring so I can only assume that the sealed bearing is a bit thicker than the old open-faced bearing. The questions I have are:

1. Is that 1mm gap going to cause problems? 2. Should I try and fill that gap with a thick washer? 3. As the ring is only biting against the bearing outer race and not against the hub, is there a chance of it coming loose over a period of time? 4. As the locking ring is sitting 1mm further out than it should, will that cause problems getting the hub to fit  in the swing arm? Thanks very much.

Regards

Tony

Submitted by robert_tuck on Thu, 03/09/2020

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I don't think its a problem. Its unlikely the dimensions would ensure that the ring fits tight to both.Has to be one or tother!.  The swinging arm has a bit of spring in it too. I have a similar issue on the Atlas where to fill a gap that should not be there we have added an additional thick washer. This has the  unfortunate result in putting an uneven pressure on the speedo drive and buckling it!.  Now I have to take some very carefull measurements to ensure it all tightens up square. So you can see why I'm interested in your issue.

Submitted by tony_wood on Thu, 03/09/2020

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Hi Robert. Thanks for the reply. I must admit that I was tempted to just see how it all fits into the swing arm before considering whether or not to attempt to engineer the exact thickness of washer required. The danger as I see it is that if the washer is too thin it will rattle and not bridge the gap, and if it’s too thick, it will prevent the locking ring from clamping against the bearing. Not an easy fix! Regards Tony

Submitted by robert_tuck on Fri, 04/09/2020

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We are thinking on different   lines, my fault,rambling on ! ,   I don't think even when new the ideal of the ring being tight to both surfaces was  expected.  Not realistic  ,more important that the ring bear down on the bearing and hold it tight .  Worry not,be happy !.

Submitted by ian_soady on Fri, 04/09/2020

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.. with Robert, its job is to locate the outer bearing race. It doesn't matter if there's a bit of clearance on the flange.

It's similar to the central spacer tube which is slightly longer than you might expect so that the inner races are all held by the spindle with no chance of an endways load on the bearing as the outer on the brake end isn't positively located so can find its own position. One reason why when you first fit a back wheel it can be a bit tight to turn until the bearings settle down.

Submitted by tony_wood on Fri, 04/09/2020

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Robert/Ian. Thanks for putting me straight on the fitment of the locking ring. There’s so much wrong with my bike that I just assumed this was yet another problem.

Regards

Tony

Submitted by russ_payne on Fri, 04/09/2020

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Agree....my advice is to make absolutely sure that you are completely happy with the assembly. Whilst, from what you've posted, there doesn't seem to be an issue (and I agree the Domi swinging arm does have some 'spring' and you could in theory adjust the right-hand spacer) but if you're not comfortable, then strip it all back, measure everything and convince yourself that it's good to go. 

The other thing I'd mention is that, generally speaking, excessive side-loads from poor assembly will kill a wheel bearing faster than the radial loads it sees when in action - that goes for ball races and taper rollers.

 


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