Mk III Rear Hub

I noticed a strange noise in my rear hub. When parked on the centerstand, if I give the bike a slight nudge from side to side, I can hear something loose inside the hub, yielding a ringing sound, like tapping a bell. While changing the rear tire I visually inspected the cush drive mechanism and all seemed in order; rubbers and lock ring in place, and no anomilies with the bearings/seals/axle. I also had the rear sprocket apart to clean & repaint and all seems fine with the stub axle, bearing, and speedo drive. There is no slop when I grab and wiggle the rear wheel and there doesn't seem to be any problem with handling. It seems as though there is something loose inboard of the cush drive that is contacting the inside of the conical hub causing the noise. It's more pronounced at certain rpm while blipping the throttle when running the bike on the centerstand, more of a rattle than a ring. Any insight would be appreciated - Thanks!

Took a look at the exploded view of the disc type rear wheel on the Andover site. Perhaps what I'm hearing is item 17, Backplate, Part Number: 064810 rattling around loose behind the drive center/ hub rubbers. Maybe the lockring (item eighteen) is loose, allowing the backing plate clearance to move about. Is there anything located behind (inboard) of the backing plate that may have come loose & is rattling around inside the hub?

Thanks?

Yep ! You've got it 100% accurate diagnosis. They all do that, Sir. It's the backing plate that you can hear rattling against the hub.

With new components (lock ring and central "spider") the steel backing plate is held tight against the hub inner web and cannot rattle. The problem is that as the cush drive does its job, the central alloy part turns to compress the rubbers and eventually wears against the lock ring allowing everything to rattle.

I have replaced several over the years but the improvement only lasts 5000 or 6000 miles. My latest "bodge" which is working so far was to remove the backing plate and use it as a template to cut a thin sheet of rubber (in my case an old Land Rover inner tube) which I then inserted behind the steel backing plate.

Tightening up the lock ring was no problem and it screws down onto the bearing in the usual way, the rubber providing just enough pressure to keep everything quiet.

Usual disclaimers etc. but I can't see any potential problems with this modification.

By the way, if you do decide to dismantle yours, contrary to what the official manual says, the lock ring is not a left hand thread. I found out the hard way ! Putting the rubbers back is also a bit of a lark and is best done with a helper to tension the opposing rubbers.

79x100,
Thanks for the confirmation. The previous owner, who stopped riding this bike in the 80's, stated that there was a handling problem that caused her to quit riding it. I guess I was concerned that something was amiss in the rear hub since I found nothing too out of whack with the frame/suspension/isolastics. Next tire change I will investigate.

Appreciate your time,