Rear wheel hub cover.

[Harry44]

Got home from a little ride and while fiddling to get a decent tick over now that I have found and fixed a problem with the magneto (it had a spacer fitted under the advance retard cable fixing that prevented the return spring from doing its job so that on full advance the timing was held steady but any other position the timing was irregular as the base plate rattled about.)

That's when I noticed the rear hub cover was loose, it was sitting between the hub and the speedo drive. I was unable to see how it should be retained as I could push it back into place but it fell away as soon as I removed my hand. Fortunately my bike lift has one of those handy trap door thingies which makes getting the wheel out easy. Comparing what I have with the pictures in the tech articles, it seems the cover should be held by the locking ring for the wheel bearing adjuster.

Having read the stuff about rear wheels locking up I decided to have a good look inside the hub. The bearings are fine and have just perceptible end float. The speedo drive nut was loose but when I tightened it the drive locked up.

I've ordered a new speedo drive a new spacer and nut for it as the threads aint too clever, new adjuster ring and lock nut to be on the safe side. Let's see what happens when that lot arrives from the spares scheme.

[clive]

The cover is held in place by the bearing lock ring as you worked out. Sounds like yours must have worn through over the years.

[oldandsmelly]

A couple of potentially baffling moments to warn you about when you fit the new speedo drive.... You may already know about these so apologies if I'm teaching you to suck eggs.

The new speedo drives available often need the central hole reamed out to fit the spindle. This isn't too difficult as the metal (at least on mine) is quite soft. The second thing, which is less obvious, is that the new drives are a slightly diferent shape front to back i.e. they are more convex (I was going to say more 'dishy' but that doesn't sound very technical). It's only a slight difference in shape but it can have the effect of locking up against the rear wheel when you tighten up the speedo drive retaining nut so that when you spin the back wheel the speedo drive tries to move with it. It's easy then to get really baffled why this is happening and start doubting the bearings etc. If this happens, just gently squeeze the speedo drive in a vice to flatten the back plate slightly, only a smidgen is needed.

[Harry44]

Don't apologise I learn something every day. I'm kinda grateful the cover fell off as it led me to spot the speedo drive problem.

My speedo drive is concave viewed from outside but why it locks up is a mystery as the nut tightens up what should be a solid piece of (soft) metal.
I've even taken out the spacer from the adjuster and with just the spacer, speedo drive, washer and tightened nut I can't turn the drive by poking a screwdriver against the drive pegs.

Hence my decision to replace every bit involved. Reading about wheel lock ups (which I'd not heard of before) makes me more determined to get it right. A seized speedo drive seems the most likely cause of lock up.

[thornebt]

I think an important thing to do is to make sure you tighten the wheel spindle fully before tightening the speedo gearbox retaining nut. Cheers. Bruce.

[Harry44]

I think an important thing to do is to make sure you tighten the wheel spindle fully before tightening the speedo gearbox retaining nut. Cheers. Bruce.

The manual says do it that way but I assumed it was just to make it easier to hold the spacer while tightening the nut.

[CliveSW]

I recently bought a new adjuster ring and found the outer diameter that the speedo drive (original type) fits over was too large and needed a lot of filing, sanding etc to make fit. I also found the speedo drive spacer which was retained in place by the original adjuster ring, slips through the new one, not a huge problem, but can make refitting the wheel awkward.

[Harry44]

My bits arrived yesterday but the locking ring won't screw onto the adjuster ring. I rang the AMOC spares people and even if I pay for another one and bin this one they still won't post me a replacement till Monday.

I'm working away from home for a fortnight so can't get the bike back together for ages.

[G15 Roy]

[quote="Harry44"]My bits arrived yesterday but the locking ring won't screw onto the adjuster ring. I rang the AMOC spares people and even if I pay for another one and bin this one they still won't post me a replacement till Monday.

Did they say why seems strange as it is only Friday tomorrow.

[ajscomboman]

My bits arrived yesterday but the locking ring won't screw onto the adjuster ring. I rang the AMOC spares people and even if I pay for another one and bin this one they still won't post me a replacement till Monday.

Did they say why seems strange as it is only Friday tomorrow.

For a minute I thought I'd lost a day! As it's only Thursday there's absolutely no reason for the part not to be packed and shipped in time for Friday's collection, or am I missing something else?