Stuck Chronometric Speedo

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Stuck Chronometric Speedo

Postby thornebt » Sun Jul 16, 2017 10:05 am

Having finally managed to sort the starting problems on my G80S I now have a new problem. The speedo is stuck at 23mph. It had previously been stuck at zero but I put an electric drill on the gearbox end of the cable and turned it anti-clockwise and it settled at 23mph and stuck there. I need to take it out on the road and hope that perhaps something will jog it back to normal operation. Has anyone had this problem please?

Cheers. Bruce.

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Re: Stuck Chronometric Speedo

Postby clive » Sun Jul 16, 2017 10:36 am

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!
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if it ain't broke don't fix

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Re: Stuck Chronometric Speedo

Postby thornebt » Sun Jul 16, 2017 11:39 am

I did use the drill to drive it anti-clockwise. I've taken the bike out for a run and the needle didn't move from 23mph. I know the speedos are fiendishly expensive! Can anyone recommend a repairer please? Preferably in the Somerset / Bristol area if possible. Cheers. Bruce.

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Re: Stuck Chronometric Speedo

Postby robcurrie » Sun Jul 16, 2017 7:45 pm

Bruce, did you perhaps oil the speedo cable just before it got stuck? Oil travels up the cable and into the clockwork. If so, you can clean it out with methylated spirits and it should work again.

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Re: Stuck Chronometric Speedo

Postby thornebt » Sun Jul 16, 2017 8:20 pm

Hi Rob

Yes, I did oil the cable. It was before I read the current thread on here about it being important not to oil them! When you say to clean it out is it possible to remove the back of it? Or is it a case of taking the bevel off and removing the glass? Cheers. Bruce.

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Re: Stuck Chronometric Speedo

Postby robcurrie » Mon Jul 17, 2017 2:10 am

I'm not sure which model you have, mine has the screw on bezel, and the works comes out after removing screws in the bottom. Try not to disturb the painted numbers on the odo with the meths!

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Re: Stuck Chronometric Speedo

Postby thornebt » Tue Jul 25, 2017 10:48 am

robcurrie wrote:I'm not sure which model you have, mine has the screw on bezel, and the works comes out after removing screws in the bottom. Try not to disturb the painted numbers on the odo with the meths!

Rob C


I took the speedo out today. It certainly appears to have a screw on bezel as I can see a fine thread. I have tried unscrewing the bezel using rubber gloves to get a good grip on the body and the bezel but cannot shift it. It's probably been screwed on for sixty years!

Does anyone have any ideas on how to shift it please? Maybe seal it in a plastic bag and put it in the freezer? WD40 on the thread? Cheers. Bruce.

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Re: Stuck Chronometric Speedo

Postby SPRIDDLER » Tue Jul 25, 2017 11:20 am

Any good?
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Re: Stuck Chronometric Speedo

Postby thornebt » Tue Jul 25, 2017 11:25 am

Hi Neville. That looks really good. Presumable it's tried and tested by yourself? I thought the wood might slip on the bezel,but perhaps some innertube rubber might help if that's the case.

You obviously had the same problem as me? Cheers. Bruce.

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Re: Stuck Chronometric Speedo

Postby SPRIDDLER » Tue Jul 25, 2017 11:32 am

thornebt wrote:Hi Neville. That looks really good. Presumable it's tried and tested by yourself? I thought the wood might slip on the bezel,but perhaps some innertube rubber might help if that's the case.

You obviously had the same problem as me? Cheers. Bruce.

No, to be honest I've not tried it but it was posted here in the 'Photos' section by the venerable ITMA many years ago.

'DCI' Clive has posted something similar in the past. He used to repair speedos until (I believe) the parts became virtually unobtainable and may have other suggestions but it's a common problem.

Just remembered that an oil filter removal strap is said to do the trick.

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