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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
 are
‘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
Clocks
Other services
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Contact details
Speedos
Rev counters
Jaguar XK 120 ( 1948 / 54 )
117.1 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    Mobile / SMS:  07831 886545
Please check the  FAQ’s page  BEFORE ringing / emailing... thank you
Continued from previous page

     To calculate the required calibration if your car is not assembled
       use the following formula... ( 6336 ÷ A ) x B x C = TPM ( cable turns per mile )
A = Circumference of a fitted tyre in inches
* ( Cross-ply  )  for Radial multiply A x  0.98 ( ie. Deduct 2% )
B = Differential / Axle ratio   
C = Number of turns @ the ‘speedo output’ on the gearbox 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 !
Typical example :
A =  80 for
Cross-ply or 78.4 for Radial   B = 3.9  &  C = 3.84
       ( 6336  ÷  78.4 ) x  3.9  x  3.84  =  1210 TPM  
Radial
       ( 6336  ÷  80 )  x  3.9  x  3.84  =  1186 TPM  
Cross-ply
        
For TPKM ( cable turns per kilometre ) multiply TPM x 0.621     
      
*Centimetres x 0.393 = inches                                              Return to previous page
Morgan
Re-Calibration surcharge
Re-Calibration surcharge
Re calibration surcharge