The Dreaded Speedo Gearbox

[Rosy]

Before I start to use my G9 is there any indication as to what might cause this to happen, at the moment my rear wheel turns quite happy when spun without any binding or noises. Is there any checks that can be done? Best to be proactive.

[clive]

Groily, any recommendations on the threading tool. Not something I have. I might be able to salvage the hub.
And secondly, does anyone know of an alternative supply of speedo drives. A toss up of the cheap ebay one that's probably not fit for purpose, or the not so cheap one that's not fit for purpose isn't exactly a choice. It could have got me killed this time.

Just an observation. My M16 has the black square edged Smiths speedo drive. Are these different to the silver rounded ones?

The internals of the two drives are the same. The torpedo shape is the later type also originally a Smiths item. The flat back screws off but the later torpedo type is crimped on.

[mikeydpippin]

Before I start to use my G9 is there any indication as to what might cause this to happen, at the moment my rear wheel turns quite happy when spun without any binding or noises. Is there any checks that can be done? Best to be proactive.

Me too I,m about ready to take my G9 out for the first time, and I've had the rear wheel lock happen to me in the past.
Had helluva job to get the rear wheel spindle out, had to replace hub in the end...
The G9 hopefully will be ok, I've tightened the gearbox nut really tight even though there is some slight movement when really heaving on the spanner.
I've marked the Speedo gearbox and the locking ring with a small red mark and will be keeping an eye on the marks also periodically checking the gearbox to check If it's getting hot 🤞🤞and of course watching the cable for any movement at the gearbox end...

[Mick D]

Hi Mike

I'd add routinely checking the rear wheel bearing play to your confidence checks.

Regards Mick

[Duncan]

I've tightened the gearbox nut really tight even though there is some slight movement when really heaving on the spanner.

I only ever only just nip mine up and they are held firm, if you still have movement after excessive force something sounds amiss.

[G15 Roy]

I've tightened the gearbox nut really tight even though there is some slight movement when really heaving on the spanner.

I only ever only just nip mine up and they are held firm, if you still have movement after excessive force something sounds amiss.

I had this happen to me once after a Mate! adjusted my chain at a IJR rally.

[ajscomboman]

I've tightened the gearbox nut really tight even though there is some slight movement when really heaving on the spanner.

I only ever only just nip mine up and they are held firm, if you still have movement after excessive force something sounds amiss.

I had this happen to me once after a Mate! adjusted my chain at a IJR rally.

Bitch, you'd done loads of miles since the chain was adjusted. That was nothing to do with me. Anyway didn't I stay with you and bail you out the shit risking missing the ferry? We still made it in time to get to the Captains table for dinner so what's the problem!!

[bob121]

Managed to save half of the threads. Enough to hold the adjuster ring firm. Drilled the hub and run a 3/16 helicoil to carry a grub screw to lock the adjuster ring in place. Can be accessed through the hole in the hub cover for the grease nipple. Will order the new parts required tonight. Hopefully be back on the road by the end of next week.

[Groily]

Speedo cable spiral.jpg

Sounds like a result Bob. Congrats!

I'm not sure whether the retainer ring undoing, or the gearbox rotating and undoing it, is the chicken and the egg on some of this. Could be, as you said, that the 'box undoes the ring if it's not that tight. In whichever case, here are my speedo cable remains, after the same general problem a few weeks back. I said three times round the axle - in fact looks like 4!
I now have the gearbox - which wasn't damaged - staying in place correctly, with the various bits all compressed tight and therefore secure, and the locking nut for the gearbox operating as it should and holding things in place by bearing only on the gearbox, and the gearbox not bearing on anything else. Darn thing!

But as far as I am concerned, it remains a thoroughly rotten way to run a railway. Even if it's only happened to me twice in nearly half a century, it's twice too often given it's never happened on any other period machine I've owned, using the same gearbox type. Just for once, I feel warmly towards the perpetual tiny oil drip from my Beesa's cable outlet on the bottom of the gearbox - the big gearbox with the gears in it, which contains the speedo drive gears, that is!

[39speedtwin]

Be wary of the pattern gearboxes from India, some have nylon or plastic gears, they wear very quickly.