Smiths Chronometric

[klaus gerhard]

I wonder where my Chrono speedo had been fitted originally. It reads on the dial: S.467/231/N and I would like to use it on my 1953 single. It has the short reset from the back and a Illumination window at the 6 o'clock position.
Any advice appreciated. Thanks
Klaus

[Richard.Carrigan]

Hi Klaus,

This speedo was used on a 1959 Triumph 3TA. It might have been used on other bikes, but I don't have all the other years of the 'Smiths Motor Cycle Equipment' catalogues to check.

Suck it and see!
Cheers
Richard

[Julian Murphy]

111 mph.

Optimistic.....

[paul.jameson]

This speedo should work quite well on an Ariel. The flex speed (rpm per unit distance) for a MPH Ariel chronometric is 1610. 1km is 0.6214 miles so the correct flex speed for an Ariel KPH speedo is 1610 x 0.6214 = 1000.454. Your speedo has a flex speed of 1050 (numbers on dial) so it should read 95% of the true speed (in theory).

Incidentally, the difference between theory and practice is that, in theory, there isn't any difference but, in practice, there is.

[cmfalco]

Speedometers (and tachometers) were made to operate with cables that either rotated clockwise or counter-clockwise. You'll need to look up the specifications of your unit to know which it is. Note which way your cable turns and make sure your speedometer is made for that direction of rotation (as viewed from the front of the speedometer).

[paul.jameson]

One of the joys of the PA and other Smiths governor speedos (and there aren't too many joys with them) is that they are designed to work with either rotation of the speedo cable - it doesn't matter which way the cable rotates on a PA or other governor.

[will_curry]

I've heard tales of 'anti-clockwise' Smith's chronometric speedos but I've never come
across one yet.

Any idea which bikes actually used them?

[Pete.Silson]

it doesn't matter which way the cable rotates on a PA or other governor

Doesn't the rotation direction affect which way the odometer turns or are they not a direct geared drive from the cable like a chronometeric?

[will_curry]

Even in Chronometrics the circular movement derived from the cable rotation is converted
into linear motion which drives the odometer wheels via a ratchet arrangement. The mileage
recorded increases no matter which way the cable turns.

[klaus gerhard]

I tried the speedo on my VHA but it seems to be blocked inside and therefore does not rotate nor show any speed. I will take it to my local speedo repair shop for their estimate. Hopefully the waitinglist is not too long.
Thanks for all your replys.
Klaus