speedo drive gearbox

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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dunsweepin
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Location: Derbyshire UK

speedo drive gearbox

Post by dunsweepin »

hi all,i read somewhere about the speedo gear box turning on the spindle and locking up the wheel with the cable.what do i look out for to avoid this when refitting my rear wheel,cheers dave
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dave16mct
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Re: speedo drive gearbox

Post by dave16mct »

It usually only happens on the heavyweight models with full width hubs when incorrectly assembled. I've never heard of it happening on a lightweight (yet!)
Dave.
dunsweepin
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Re: speedo drive gearbox

Post by dunsweepin »

cheers for swift reply dave,will press on with refit
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Rob Harknett
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Re: speedo drive gearbox

Post by Rob Harknett »

Speedo drive turning and winding up the cable on heavyweights, causing the wheel to lock, is due to the nut that tightens it is loose.
The nut in question can only be fully tightened after the wheel has been fitted and spindle nut fully tightened. In reverse. If you need to remove the speedo drive, you need to slacken off the speedo drive retaining nut first. I've never had a light weight drive off, I guess lightweight wheels have a different assembly.
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clive
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Re: speedo drive gearbox

Post by clive »

dave16mct wrote:It usually only happens on the heavyweight models with full width hubs when incorrectly assembled. I've never heard of it happening on a lightweight (yet!)
Dave.
Not sure that it only happens when incorrectly assembled. If the worm drive is worn then it and the ring in the Speedo drive box can cross thread and seize. This will then tend to turn the drive box with the wheel and rip the cable from the head.
clive
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Janet
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Re: speedo drive gearbox

Post by Janet »

dave16mct wrote:It usually only happens on the heavyweight models with full width hubs when incorrectly assembled. I've never heard of it happening on a lightweight (yet!)
Dave.
Why wouldn't/couldn't it happen on a lightweight? I'm aware that lightweights and heavyweights have different types of spacers, nuts etc, but isn't the basic method of holding it all together the same? It's a serious question. Unlike some other people, I do have intimate and, sadly, frequent knowledge of what's fitted on my lightweight rear wheel spindle, but I don't know what's on a heavyweight.
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dunsweepin
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Location: Derbyshire UK

Re: speedo drive gearbox

Post by dunsweepin »

more great answers thanks to all for replies
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dave16mct
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Re: speedo drive gearbox

Post by dave16mct »

On the heavyweight full width rear hub, the speedo drive fits on the bearing adjuster. If assembled incorrectly this can unscrew causing all kinds of damage. The lightweights have non adjustable bearings, so the speedo drive fits directly onto the hub. Obviously make sure it's located propery on the slots of the hub and is in good condition. Same applies to pre full width hub models. Not sure about '63 inerim and '64 on Norton wheels.
Cheers Dave.
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Janet
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Re: speedo drive gearbox

Post by Janet »

Ta everso.

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