Creepy - my speedo drive turns on the axle??

I am having trouble with the drive on the rear axle, even though I tighten it up, it seems to creep clockwise and stress the speedo cable (drag it down). I have already had one inner cable fail because of this. I noticed the axle collar/spacer was missing from the drive and copied the one from my 750 and fitted it. Everything tighten up again but it still moves, has a mind of its own! The gearbox works fine and is nice and smooth in operation.

Seems some sort of dark force at work here, as I cannot understand how it can move - any ideas?

like center stands, Commando speedo drives are arguably dangerous

I have seen a rider go down when the speedo cable tore loose and got wrapped into the rear wheel spokes

20 years ago I did away with my speedo drive and cable for this reason, but now eyeing the new electronic one

regardless, tightening the right side axel clockwise will rotate the speedo drive while torquing correct,
but who cares as long as it stays put when the tire moves, it does do that?

just zip tie the cable to the swingarm about 6 inches forward of the drive unit.

This is the weird thing, the axle spindle is tight and the cable zipped to the swinging arm. Regardless of this, it still seems to creep round and the cable no longer runs away straight but has a bend just after exiting the drive?

ah, I seem to remember having your problem!

inside of your speedo drive, is there a "top hat" spacer in place?

OR, perhaps the drive cogs are not in place with the notches? as in don't have it fitted in place correctly?

1up3down said:

ah, I seem to remember having your problem!

inside of your speedo drive, is there a "top hat" spacer in place?

OR, perhaps the drive cogs are not in place with the notches? as in don't have it fitted in place correctly?

Click to expand...

Just had this problem on my Matchless when refitting the rear wheel. The drive cogs were not engaged in the wheel slots. Took the axle out again and made sure the cogs were engaged. A little tricky. Went in a lot farther on the 2nd try.

The top hat spacer was missing so I turned one up and fitted it. Drive seems to be engaged correctly?

you made a top hat spacer yourself?

from memory with the right dimensions?

order a new proper one, no offense, just saying.....

or just take the damn thing off, who cares how fast you are going anyway as we never, ever speed

Nigeldtr said:

The top hat spacer was missing so I turned one up and fitted it. Drive seems to be engaged correctly?

Click to expand...

The body/shell of the drive is quite soft and can flatten or bow out causing undue friction where it doesn't belong. They are not hard to pop out or in a little depending on which way yours may or may not be flexed.

A sure tell is usually on the aluminum hub cover.

So like when was the last time you greased the box and the cable.

Plenty of grease in the drive and I put some EP 90 in the cable a few days ago. I'll take a look and see if the housing twisted.

Nigeldtr said:

Plenty of grease in the drive and I put some EP 90 in the cable a few days ago. I'll take a look and see if the housing twisted.

Click to expand...

When you turn the tabs that engage into the wheel hub, does it turn freely all around. It should.

Yes, the central wheel is free an turns easily. Seems rather odd as all appears Ok? I will also try running without the cable and see if anything moves.

Nigeldtr said:

Yes, the central wheel is free an turns easily. Seems rather odd as all appears Ok? I will also try running without the cable and see if anything moves.

Click to expand...

Creepy!

Are you sure the box hasn't taken to move itself towards the hub? For some reason they tend to do that. I pressed mine out at the top hat so the box didn't hit the hub cover, you can tell if there are marks on the hub cover and also on the GB, or just look at it and see if you can get a good sized feeler between them. There should be a decent clearance between the hub cover and the GB. I think I've got about 3/16" on mine, and I keep an eye on it.

I've seen the steel pressed in seal retainer for the felt be overly rounded out, fouling on the hub. Some judicious drifting flattened it out some.
The spacer you turned, no doubt is a GOOD copy of the original you had to measure. However, the soft gearbox body is likely wallowed out, and is no longer a tight fit on the spacer. Spin one up .005" oversize and see if it helps.

the speedo drive should be held solidly between the outer spacer and the spacer that contacts the bearing. If it moves, it has to be because the main bolt is not tight. Or, Your problem may be that the alumium part of the speedo drive is coming loose on the steel part which is squeezed between the spacers. You might have to unscrew the driven spindle, and make up a part like that used on the old hub brake on a push bike. [ or maybe throw it away and buy a new one. ] If you do that, save the gears for future use.

Might want to just bite the bullet like a tire and replace as part of normal dissolving Commando items. The speedo shell can get eaten away where top hat lip sits so lacks enough clamp force to fix on bearing race instead of dragged around. I've had a speedo lock up before I learned the spacer was missing till cable broke on Peel to shock me and whip snot out of rear but was going slow on grass as rear self braked so didn't go down. Btw you do know about the non factory rear brake lever anti-pogo cable break safety spring. Extra axle torque won't likely do anything but give more proneness to fracture at the dumb axle. Just enough not to let DS chain pull tug the TS axle backwards if your adjuster don't fix it in place then maybe a bit less. I've been though 4 and was sideline hobby watching for bargains to always have a spare on hand and amazingly enough still do as after changing my ways the one I pulled off Peel for Trixie is still tight and steady drive w/o slinging grease for 10K-ish miles so far and may double that at this weird rate. Even the ring rivets still snug as a bug in a rug. Trixie Speedo quit working 1000 miles prior and 1st thot uhg was another speedo drive but cable broke first so removed it to give the poor drive a rest.

Thanks for all the posts.

Tomorrow I will fit a new rear tyre and check all the bearings and spacers etc. again. I had the brake drum off last week and cleaned up everything, re-lubed the pivots etc with copper slip and popped in a washer to stop the shoe retaining bolts rubbing the rear of the drum - seems to be a washer listed in the parts list (Part 21 WASHER NME 5276) but there was nothing in there? Apart from this, everything seems ok.

When I checked the axle today, it was as tight as I did it up and for that drive to move round there must be something weird happening. I am sure the wheel balance is way off (can feal the rear end vibrating at hi speed) and will fix this after the new tyre is fitted. Do they normally have tyre clamps on the rear as I can't see one? Do you think the vibs from the out off balance rear wheel could be enough to flex the axle and let the drive slip - bit of a long shot I know?

So just a concluding update. Before changing the rear tyre I thought I would check the balance - needed 54 gm, about 2oz :shock:
Changed the tyre and checked the balance, needed 18 gm, just over 1/2oz, which I added and when road tested much smoother. Guess what, the speedo drive now stays put. I can only guess that the rear axle was bending and wiggling about so much the drive was able to "slip" .

PS Cush drive was also shot ( pads fallen to bits) and probably most of the load was being taken over one pin :!: . Missed this when I had the drum off but done now.

Thanks for all the help, very much appreciated