Right
Up to now I have had to react to all my problems so for a change I am going to be pro active.......

I have a smiths mechanical speedo, origin unknown and a ford four speed type E gearbox. I'm guessing that the speedo will not be matched to the box. I know this can be re calibrated but my questions are :-
1.... Who does it near lancashire
2.... What will they need, the speedo obvoiusly but will I need to count teeth on speedo drive, diff etc.

Anyone had to do this ?

Cheers

RD

I watch this with interest, as I have a VDO speedo to mate to my Type 9 5-speed box and I'm sure I'll have similar questions (except the Lancashire bit, 'cos I'm in Wiltshire ).....

theyd need to know about the gearbox speedo drive, diff, and tyre size i'd imagine. best place to send it is probably going to be caerbont instruments since they make them. www.caigauge.com i think

maybe wait til the cars all finished, try it, see how far out it is, then tell them the shown speed and actual speed, and they could probably sort it that way too

You will need to know:

The circumference of the tyre (mark tyre and ground, roll forward one revolution, mark ground again, measure length). You can also look up typical values based on tyre size - bear in mind tyre wear affects this.

Number of turns of speedo cable for 1 turn of the wheels (both wheels need to be turned the same, you can do this by rolling the car). Best to do 10 turns of the wheel for better accuracy and stick a cardboard pointer on the end of the speedo cable.

If the gearbox isn't in the car then do the same for turns of the gearbox output shaft but you will need to tell the calibrator your diff ratio as well.


[Edited on 8/10/09 by matt_claydon]

Speedy cables calibrates them, their webpage tells you what they need to know.

http://www.speedycables.com/calibration.html