Speedometers and Cables

Speedometers became a legal requirement, in the UK, on 30th September 1937; machines manufactured prior to this still do not have to have one. In spite of this requirement, Ariels continued to list the speedometer as an extra for many years although the vast majority of machines had them fitted at the factory. The Smiths governor type of speedometer was fitted from 1933 until 1946 except for the W/NG models and those where a front wheel drive Smiths Chronometric was specified by the customer which was an option from 1938. The governor speedometer is usually called a ‘PA’ because this is what is on the face! The Chronometric type was standardised from 1947 onwards. The drive ratios are quite different for the two types which means altered drive gears in the gearbox, an additional set being added in 1950 when it was discovered that the first Chronometric set was incorrect, advice on this minefield will be given. When fitting a reconditioned speedometer it is advisable to also fit a new cable as an old one may damage the new unit. Test the cable by holding one end of the inner cable and attempting to twist the other end, more than ½ a turn indicates that it should be replaced. We do not supply or repair speedometers.

Cross section through speedo bezels