Speedo Gearbox Lockups

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Speedo Gearbox Lockups

Postby Eamonn » Thu Dec 24, 2009 6:41 am

A common problem experienced by many owners is the rear wheel suddenly locking up - pulling the clutch in makes no difference and you skid to a halt hopefully without falling off.

The first thing to check is the speedo gearbox on the rear axle and chances are that you'll find the speedo cable wrapped around the rear axle thus causing the lock up. The reason for this is the incorrect assembly of the various washers, spacers and seals on the rear axle/gearbox assembly. If the components are not assembled in the right order, the speedo gearbox can be caught up with the rotation of the rear wheel and therefore causing the problem above.

To see how the components should be put together, read the article by clicking on the link below.


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Speedo Gearbox Lockups

Postby SPRIDDLER » Thu Dec 24, 2009 9:55 am

Not forgetting Biscuit's brilliant cut-away photo of the assembly:

I poke badgers with spoons.....from 2 metres.

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Speedo Gearbox Lockups

Postby One pot » Thu Dec 31, 2009 5:48 pm

Hi thanks for this.

I similarly had a gearbox seizure, but at 10mph the cable was just yanked out ot the speedo and I managed to stop with full control.

During post-incident stripping all parts were correctly assembled.

The cause of my speedo gearbox seizure was a very worn output pinion. The gear profile on the pinion was down to a knife edge, and with some axial movement of the pinion the mechanism jammed.

Just another little thing to keep an eye on!

One Pot
If Something goes wrong, check the last thing you mended first

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Speedo Gearbox Lockups

Postby Peter Lecompte » Tue Feb 15, 2011 11:32 pm

I like the article by Eamonn and the cut out by biscuit. I do realise that these are for the full width hubs, not the steel hubs for the earlier models. So, is there someone out there that has a similar "how to" guide for the earlier hubs. in particular around late 1940's and early 1950's? or is there just too many variations between those years with the complication of the mixture of Rigid and Springer rear ends? Cheers Peter

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Re: Speedo Gearbox Lockups

Postby nortonbrian » Tue Nov 13, 2018 9:31 pm

slid to earth twice while testing in 1960's. rear wheel bearing adjusters not machined concentric, but a 20 years old just shrugged it off, now be sore for a week !

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