All about Sunbeams S7 and S8 .
  • SUNBEAM MOTORCYCLES. HEADER PAGE.
  • Sunbeam News
  • About the bike.
  • Distributor Internals
  • Redundant spark ignition.
  • Coil Information.
  • Beam-Spark Ignition Unit
  • FOR SALE
  • Smiths Chronometric Speedometer
  • Calibrating Smiths Chronometric Speedometer.
  • Speedometer Drives.
  • Companies and Products.
  • My other bikes.
  • The Horn. and Rear Brake Spring.
  • HOW TO PAGE
  • Modifications Page One
  • Modifications Page Two
  • Modifications Page Three
  • Dipsticks,sumps and oil weirs.
  • The Electrics
  • Sunbeam Dynamo in depth.
  • Repairs and Maintenance.
  • Carburettors
  • S8 Front forks.
  • Full width front brake on the S8.
  • Top dead centre.
  • Your Sunbeam.
  • All things wheels.
  • Data Sheets.
  • Engine breathing and oil leaks.
  • Putting the engine together.
  • Stainless Steel Exhaust
  • Tools
  • All things final drive
  • I80 Degree Crankshaft
  • Completed engine speed ignition sytem.

Smith's Chronometric Electronic Speedometer.

Smith's Instruments are still manufactured in the UK as they have been for countless years, and in one of the last surviving factories. The digital motorcycle instruments were reintroduced three years ago and are manufactured in this same factory in Wales. 
These cover chronometric speedometers and tachometers made in the 1940's and 50's. Plus the magnetic types made in the 60's. These instruments are UK manufactured and are of the highest quality. The bodies are CNC machined to the same dimensions as the originals. Early types using the screw on bezels are standard thread so OEM bezels fit perfectly.The case now incorporates a seal to stop the ingress of water round the glass.The big difference with these instruments over their predecessors is the fact they are electrically driven. In the case of the Sunbeam twin engine where the speedometer drive is taken from the gearbox, Smiths supply a gearbox transducer which fits in the place of the original cable. This transducer sends electrical pulses to the speedometer via two thin wires, hence no bulky rotating cable. This is a boon for Sunbeam owners as the original cable running under the petrol tank is somewhat clumsy. Plus the original Sunbeam chronometric speedometers are unique in having a right angle bevel drive which is impossible to obtain nowadays. So if you are looking for a Smiths chronometric speedometer for your Sunbeam contact them at
                                                                                    www.smithsspeedos.co.uk

Really helpful  people. When ordering please specify if you want the bezel to be flanged to fit in the headlamp shell.

The instrument itself is switchable between smooth mode and tick mode, that is the needle can sweep the dial or step as in the original mechanical instrument. The display window shows both total mileage and trip mileage at the touch of a button. LED illumination is built in.  All in all a very clever piece of design, plus it is British !
I found in my paticular instance by the time I had bought a secondhand instrument and then had it restored the cost was more than a new Smiths electronic speedometer.
Gearbox type transducer cable. This comes with a small brass sleeve that fits over the square shaft. This brass sleeve is important as it ensures the drive is a snug fit in British speedometer drives. Make sure the brass adaptor is fitted up to the shoulder of the square shaft.
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Transducer fitted in gearbox using standard cycle thread fitment. Thin cable coming out of top is two wires in a sheath to go to speedometer.
Compare this with pictures below.
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View showing flush mount bezel.

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Front of instrument showing total and trip mileage window. The very high quality of build is apparent in the dial and needle.

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Rear of instrument showing it is electrically driven. Wiring for speedometer is very simple.
One pair of wires to positive ( 12 volt ) through ignition switch.
One pair of wires to negative.
One wire to lighting circuit.
One wire to reset switch ( to earth ).

The speedometer spigot is a dummy and can be removed and a blanking plug inserted. Clever people these Smith's boffins !


The speedometer on a six volt bike.
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Small rechargeable six volt battery as used in burglar rechargeable systems will provide the very small current, around 40 milli-amps for the speedometer.

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The header picture shows the total mileage counter, so here is the tail picture showing the trip mileage.
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