electronic and mechanical speedometer conversions..

electronic speedo conversion

Available for most popular Japanese imports with electronic speedometers, this top quality conversion utilises the original Japanese 180 kph speedometer and in effect converts it to 180 mph. An mph decal is provided to cover the kph legend on the original speedometer face. With this conversion, the original Japanese 180 kph (112 mph) speed limiter is disabled and the odometer will commence to record in miles. Fitting instructions are included. Beware of cheaper but inferior electronic conversions - we have used this make for many years and when correctly fitted, have found them to be extremely reliable.  
Prices from £64.95 including VAT (parts only)

fitting information.. 
job difficulty varies considerably depending upon vehicle, but basically the unit normally has four leads and you will need to identify on the vehicle a 12v supply, an earth and the pulse feed to the speedometer. Once you have sorted the live and earth, utilising the two remaining leads, the unit is connected between the speedo pulse supply wire of the vehicle's harness and the speedometer itself. The conversion thus interrupts the signal to the original kph speedometer - in effect converting the existing 180 kph display to 180 mph. Whilst there is no needle to mangle, as in changing a dial face, we would suggest that if you have wiring harness dyslexia and/or cannot operate a soldering iron without burning your hand, then this is a job for a specialist. 

if you have a cable driven speedo..
then you will need a mechanical conversion. This is a small gearbox that normally fits between the gearbox speedometer output and the speedo cable. Once again the original Japanese 180 kph speedo is retained and is thus converted to record up to 180 mph. An mph decal is provided to cover the kph legend on the original speedometer face. With this conversion, the original Japanese 180 kph (112 mph) speed limiter is disabled and the odometer will commence to record in miles. Prices from £99.00 including VAT

sva information..
it is an SVA requirement that speedometers record in miles per hour. Furthermore, as part of the SVA test, the speedometer is checked for accuracy on a rolling road. Fitted correctly, an electronic or mechanical conversion should be sufficiently accurate to comply with SVA requirements. 

general information..
Under UK vehicle Construction and Use regulations, it is a legal requirement that most vehicles used on public roads must be equipped with a functioning speedometer recording in miles per hour. The vast majority of  vehicles imported into the UK, with the exception of the USA, will have KPH speedometers and odometers recording in kilometers.

All Japanese domestic market vehicles are limited, by Japanese law, to a maximum road speed of 180kph (112 mph). Delimiting and the simultaneous conversion of a kilometer odometer to record in miles can be achieved by utilising either the electronic conversion or the mechanical gearbox detailed above. A simple speedo fascia conversion (go here) has no delimiting effect and does not alter the vehicle's odometer, which will continue to record in kilometers. 


For more information or to place an order, please telephone 0191 586 7724
or you can email us here:



back to parts page



Copyright © Towertyre Limited t/a SMC
All rights reserved