Information required to Check / Re- Calibrate a Speedo
                                                                                                                    print off a copy & enclose with your order...    
*Jack up just 1 Driven wheel  Measure the Circumference of the fitted tyre in inches  = _______  cms  = _______
Remove the Speedo...make up a cardboard pointer or similar & fix it to the end of the exposed inner speedo cable
Put a chalk mark etc on the edge of the tyre & the ground ...
Now  turn the ‘Jacked up’  wheel 20 turns forward ( out of gear )
& count the number of turns the speedo cable makes = ___________  to the nearest 1/8 ( eighth ) of a turn

* The above assumes a Normal diff unit ... if the car is fitted with a Limited slip diff  ( LSD)...
Jack up  Both driven wheels  & turn one wheel 10 turns forward ( out of gear )
take up the ‘LSD’ slack first  ie. until the OTHER wheel starts to turn  ( approx ½  turn  )  
Please state the FULL tyre size _____________________    & type eg.  Radial  /  Cross-ply  ( delete one )


However if your car is on the road & running ask a friend etc to pace you in another car *  with a speedo known
to be ok... ie. set the Trip on both cars to zero ... Travel approximately 10 miles / 16 Km & advise both readings
eg. True distance = _______  Your cars indicated distance = ________  to the nearest 1/10 ( tenth ) of a mile / Km
*Or use a ‘reliable’ Sat-Nav  ...ie.  Most classic cars have a more ‘upright’ windscreen’ which can limit the satellite view...

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