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Dimensions of the two nuts for the Smiths Speedometer

Hello.

Can somebody tell me what are the dimensions of the nuts that are used to screw the speedometer to the speedo bracket for a BSA M20 1940.



BR; Mitja

email (option): mitja.peterka@siol.net

email (option): mitja.peterka@siol.net

Re: Dimensions of the two nuts for the Smiths Speedometer

6mm dia. x 1mm pitch...Ian

email (option): ian@wright52.plus.com

Re: Dimensions of the two nuts for the Smiths Speedometer

My understanding is that Smiths Industries bought the patent for their speedometers from Jaeger of France and therefore the 2 nuts that hold the speedo on are the only metric fasteners on British Motorcycles.

Re: Dimensions of the two nuts for the Smiths Speedometer

Yes, but with imperial hex!
Jan

Re: Dimensions of the two nuts for the Smiths Speedometer

Hi All
Mine appear to have 0 BA size nuts - hard to tell if the stud is BA or Metric.
Cheers
Doug W

email (option): watsond@xnet.co.nz

Re: Dimensions of the two nuts for the Smiths Speedometer

I think 0BA is spot on. Ron

email (option): ronpier@talk21.com

Re: Dimensions of the two nuts for the Smiths Speedometer

I actually thought they were 0BA...However, I keep reading/hearing that they are metric, based on the fact that Jaeger speedos (from where the Smiths licence came) were manufactured in France...Ian

email (option): ian@wright52.plus.com

Re: Dimensions of the two nuts for the Smiths Speedometer

Me too and I was also getting influenced by the 'French Connection' 0BA makes better sence as it's the same tpi and diameter with an imperal hex. I doubt there were many metric spanners back then. Available here in brass or steel https://www.ba-bolts.co.uk/brassnut.html
Ron

email (option): ronpier@talk21.com

Re: Dimensions of the two nuts for the Smiths Speedometer

Smiths were initially agents for Jaeger in the UK and it was a requirement that there should be full parts interchangeability with the Continental-manufactured instruments. This would have included cases and bezels and meant that their parts could be used on foreign vehicles as well as bought-in by Jaeger where needed.

However, UK vehicle manufacturers would have expected imperial hexagons on any fitings, hence the odd combination.

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