Stuck Chronometric Speedo

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Re: Stuck Chronometric Speedo

Postby clive » Fri Jul 28, 2017 8:43 pm

Harry44 wrote:That nylon spacer that's broken. Is it meant to be attached to the inner cable to stop it sliding down inside the outer cable too far and no longer drive the speedo ?

The other end of the cable which fits in the drivebox would stop that, put to prevent pre loading the cable has a small round bush attached to the inner and this sits between the top of the cable outer and the speedo.
clive
if it ain't broke don't fix

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Re: Stuck Chronometric Speedo

Postby clive » Fri Jul 28, 2017 8:48 pm

clive wrote:Our Speedos are clockwise drive when looking down on the cable at the Speedo end from above. If you use a drill to drive them it needs to be set in the reversing mode. If you were driving it anticlockwise looking from the gearbox end it ought to read the speed. It may be that if you turn the cable slowly by hand that it will drop back to zero. The smiths Speedo tests the speed about every 6 feet on the road. If you stop the drill dead at the wrong point it may not zero. Then again it may be knackered!


thornebt wrote:Thanks Clive for so much information. You say in your post:-

...you can use a drill with a reversing feature. The cable has to turn clockwise when looked at the chuck from above. Depending on the speed of your drill the speedo will probably show between 40 and 100 mph (1600rpm is 60 mph). Again when you stop the drill it will probably not stop at zero until you turn it slowly again.

This is exactly the situation I have.

Perhaps I need to try it in the bike again as it might work correctly now. I guess the difference between using the reverse drill and the bike to drive it is that the drill stops almost instantly with the result that the speedo sticks until slowly rotated again - whereas the bike decelarates more slowly which enables the speedo to gradually tick down to zero.

I'll do as you suggest with the cable as well.
Cheers. Bruce.


oops Bruce thats exactly what I said a couple of pages ago! had you confirmed this I would probably have said it might well work on the bike. Replace that cable its duff if it needs that spacer.
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Re: Stuck Chronometric Speedo

Postby thornebt » Sat Jul 29, 2017 2:47 pm

Thanks Clive. The speedo seems to work fine on the electric drill but stuck at 10mph when I put it back in the bike. So, as you say, it must be the cable at fault. I'll get a new one and will take it from there. I appreciate your help.

I did give the speedo a spray with a switch and contact cleaner which also contains a very light lubricant. Thank you Rob H for that idea. I thought there was little point in taking it out of the bike if I didn't do anything to it. I got quite a lot of black specs of dirst out of it so hopefully that did some good.

There are only a couple of things I don't particularly like on my Matchless! The speedo gearbox which has given me problems in the past but now replaced with a new one - and that 'clip' with the screw that locates behind the top of the headlamp rim to hold it in and which takes me about half an hour to get it to actually hook behind the rim! Perhaps I'll get a new one from the spares scheme when I get the cable. Maybe a previous owner altered the shape of it somehow.

Cheers. Bruce.

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Re: Stuck Chronometric Speedo

Postby Mick D » Sun Jul 30, 2017 7:15 am

Hi

The headlamp rim clip was a little challenging on my restoration - I had bought a new rim and clip, however the powder coating to the shell resulted in the rim not fitting. Careful flattening of the folded area on the rim and some removal of the powder allowed the rim to be fitted but now the clip didn't. Comparison of the original and new clips showed the new one didn't project forward as far as the original, so I ended up cleaning out the thread of the original and using the chrome screw from the new one.

Regards Mick

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