BSA Owners' Club Forum

The BSA Workshop => Twins => Topic started by: MALCOLM.JOHNSON on 19 February, 2017, 20:28:08

Title: SMITHS CHRONOMETRIC SPEEDOMETER - LUBRICATION.
Post by: MALCOLM.JOHNSON on 19 February, 2017, 20:28:08
I have removed the bezel, glass and instrument mechanism, to allow me to do a proper job of re-painting the case, cleaning glass etc. I have no intention of any further dismantling as the speedometer seems to work fine, despite no motion over many years standing unused. Have members any thoughts about taking the opportunity of lubricating the mechanism while it is possible to do so? I had wondered about a light spray with WD40 allowing time to drain off before reassembly back into the case.
Title: Re: SMITHS CHRONOMETRIC SPEEDOMETER - LUBRICATION.
Post by: Arthur on 19 February, 2017, 20:54:41
Don't use WD40 - it has almost zero lubricating properties and could wash away any existing lubrication!

I have a feeling that the internals of a chronometric speedo should be regarded in the same way as a clock mechanism and I would therefore use extreme caution before trying to lubricate it. Need to find out what form of lubrication is used in the chronometric - could be self lubricating or even greased.
Title: Re: SMITHS CHRONOMETRIC SPEEDOMETER - LUBRICATION.
Post by: STAR TWIN on 19 February, 2017, 22:25:43
Watchmakers have 2 preferred lubricants. Whale oil and the grease from the side of your nose. If you ever see a watchmaker assembling a mechanism, spot the casual wipe of a spindle against his nose. Seriously. Generally speaking, brass components will not require lubrication.
Title: Re: SMITHS CHRONOMETRIC SPEEDOMETER - LUBRICATION.
Post by: JulianS on 20 February, 2017, 10:00:37
If it is working OK I would avoid tampering. It is easy to upset the mechanism.

However  if you wish to service it there are a number of articles to be found on the internet which will give you some insight into the workings.

This link is one such;


http://www.wdbsa.nl/Jaeger-Chronometric-Overhaul.pdf
Title: Re: SMITHS CHRONOMETRIC SPEEDOMETER - LUBRICATION.
Post by: Arthur on 20 February, 2017, 10:38:08
Apparently, the Smiths chronometric speedo main bearings are lubricated via felt pads and clock oil. If the speedo is apart, I might be tempted to give then a drop more of clock oil on these pads if you can get to them.
Title: Re: SMITHS CHRONOMETRIC SPEEDOMETER - LUBRICATION.
Post by: MALCOLM.JOHNSON on 20 February, 2017, 14:03:48
Thank you all for your replies. That article is a great asset Julian. I have printed that off for future reference. Oil the little pads seems the answer. Great.