Author Topic: A65l gearbox driven speedo  (Read 258 times)

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Ian haines

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A65l gearbox driven speedo
« on: 25 September, 2017, 11:57:05 »
Hello to all,
     I have my son's bsa a65 to mot.He is a member I have joined as a guest as am having great trouble finding correct speedo drives,there seems to be a lot of options.
   On stripping the side case and inner cover the gear on the end of shaft is missing but worm gear to cable an 11tooth is in outer case to cable. I ordered what was thought a match with dragonfly but it did not mesh and was to long. I am told it may be an ex police bike. The club has dated it to April 1965 but never registered.
Can anyone help to see if the police had a different set of gears. Many thanks a frustrated dad

JulianS

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Re: A65l gearbox driven speedo
« Reply #1 on: 25 September, 2017, 12:11:41 »
There were a number of different speedo gear sets, depending on whether chronometric or magnetic speedo, model and size of wheels, gearbox and rear wheel sprocket.

First photo from the workshop manual and second from the parts book.

Ian haines

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Re: A65l gearbox driven speedo
« Reply #2 on: 27 September, 2017, 10:48:02 »
Hi Julian,
Thanks for that, I think mine is ex police. It has a 42 tooth  rear sprocket & 19 t eng sprocket  18" wheels
With 3.50 x 18 tyres. Which says should be 8 t + 12 tooth marked D. But unless the drive is different there is no bushing in my case to support the end of the drive gear although there is an 11 tooth worm gear in the case.was there a different case for police bikes.
Thanks Ian.

JulianS

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Re: A65l gearbox driven speedo
« Reply #3 on: 27 September, 2017, 11:15:58 »
Please post a photo of the case and parts, might be able to decypher it then.

Is the speedo chronometric or magnetic?

Trev

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Re: A65l gearbox driven speedo
« Reply #4 on: 27 September, 2017, 13:59:17 »
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Is the speedo chronometric or magnetic?
Did not the police only use chronometric?

JulianS

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Re: A65l gearbox driven speedo
« Reply #5 on: 27 September, 2017, 14:08:44 »
Yes usually - they needed to be calibrated and certified for evidential use and the cheaper magnetic clocks were not accurate enough or reliable enough.

Trev

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Re: A65l gearbox driven speedo
« Reply #6 on: 27 September, 2017, 14:15:37 »
Yes found it: Chronometric up until 1974 Source:  www.chronometricspeedos.co.uk/
Quote
Chronometric Speedos were fitted to motorcycles up to 1963 and on police motorcycles up to 1974

JulianS

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Re: A65l gearbox driven speedo
« Reply #7 on: 27 September, 2017, 16:09:52 »
The early speedo driving gears did not have a shaft extension which needed a bush in the inner cover, and as far as I am aware this type of gear went with the chronometrics fitted to the early bikes.

The Smiths lists show the A65 equipped with a chronometric up to the 1963 season and magnetic after then. But Police would have needed the accurate chronometric.

This link takes you to photo of an early gear;

http://www.klempfsbritishparts.com/GEAR--WORM--SPEEDO-DR--6T-0

If your ex police bike was fitted with a chronometric then I presume it would have been fitted with the early type gears hence no bush in the cover.

Ian haines

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Re: A65l gearbox driven speedo
« Reply #8 on: 27 September, 2017, 22:30:11 »
Thankyou to you both,
As you can tell I am a novice on the web. I tried to send pictures but I was not successful.
But the info you have given me sounds right, the bike frame is 1965 the eng is from 1963.
The gear you show me dr6t looks right as if it would fit is there a part no for the other drive to match, in case mine is wrong...and as the drive does not have a bush is it just held in by the pin.
Many thanks I think we are getting there.
Ian.

JulianS

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Re: A65l gearbox driven speedo
« Reply #9 on: 28 September, 2017, 12:48:21 »
Photos from second A65 parts book.

Is the engine a police engine or is it just the frame.

The speedo you have fitted needs to match the speedo driving and driven gears, different for chronometric and magnetic and the cable for chronometric and magnetic are also different and not interchangable

Ian haines

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Re: A65l gearbox driven speedo
« Reply #10 on: 29 September, 2017, 15:50:06 »
Hi Julian,
                Not sure if engine is police but bsaoc dated it to 1963 , eng no is a65l 15521.
There is no Bush in outer case it has an 11tooth gear in it unmarked. But it has a chronometric speedo and cable fitted to the worm gear, only thing missing is the Drive gear.
Reading all the information given I think it must be the drive trev sent which was part 68-0315 Dr 6t.
I will order one and keep fingers crossed.
Will keep you posted it may help others. Many thanks Ian

JulianS

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Re: A65l gearbox driven speedo
« Reply #11 on: 29 September, 2017, 16:21:21 »
Am I correct in reading the engine number as A65L 15521?

Ian haines

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Re: A65l gearbox driven speedo
« Reply #12 on: 29 September, 2017, 19:17:10 »
Yes Julian that is on left crankcase and club says it is 1963.

JulianS

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Re: A65l gearbox driven speedo
« Reply #13 on: 29 September, 2017, 20:12:05 »
Ian

I have sent you a PM please check under "my messages" at top of screen.

Julian