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Good  luck with your project’...  Enjoy your classic motoring...
Fixed price repairs are based on the assumption that unit/s received
‘original & complete’... a surcharge may be applied to cover
missing  parts etc...  If in doubt send in the unit for inspection

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Mileage correction
Other services
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Contact details
Rev counters
Jaguar XK 120 ( 1948 / 54 )
1109.1 M
Parts Order E-Mail Link
Payment options
Payment options
Payment options
Payment options
JDO Instruments
Classic Car Instrument Repairs ( Est 1963 )
Fixed price repairs for most British & European Classic Car Instruments
48hr service  
available... Why pay more & wait longer ! No UK vat
Tele: (UK)  01535 672125 (2 lines)  Mobile: 07831 886545
Please check the  FAQ’s page  BEFORE ringing / emailing... thank you
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If you are still ‘building your car’
The Speedo calibration can still be established providing you know the following information ...
Axle / Diff-ratio #  / Circumference of a fitted tyre ( correctly inflated ) / Number of turns the
‘Gear box Speedo output’ makes for
10 turns of the ‘ Prop-shaft output ’*
*( don’t forget to take any  ‘RIGHT ANGLE DRIVES’  into account e.g. Some drive units are not always 1:1 ! )

# To establish the ‘Axle / Diff-Ratio’ ... Lock one wheel / hub & turn the other wheel / hub 20 turns
( 10 turns for LSD... without locking a wheel / hub ) take up the slack first... ( approx ½ turn )
Count the ‘Prop-Shaft’ turns & divide by 10 to give the ‘Axle / Diff-Ratio’ ...
e.g. 37 turns = 3.7:1 & 42.5 turns would be 4.25:1 etc   

( if any of the above is not clear please ring / email for help / advice )
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Calculation page
Calculation page
Calculation page 1
Re-Calibration surcharge
Re-Calibration surcharge
Re calibration surcharge