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J D O Instrument Engrs
Classic Car Instrument Repairs ( Est 1963 )
Tele: (UK) 01535 672125 Mobile / SMS: 07831 886545
Fixed price repairs for most British & European Classic Instruments
48 hr service available... Why pay more & wait longer ! no vat
48 hr service available... Why pay more & wait longer ! no vat
‘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
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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check that you are looking @ the latest version... click here
Tip! Press F11 for a full page view @ 1024 x 768 screen resolution
press F11 again to revert to normal view contact the webmaster
Jaguar XK 120 ( 1948 / 54 )
108.1M
Payment options
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
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
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-
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-
( 6336 ÷ 78.4 ) x 3.9 x 3.84 = 1210 TPM Radial
( 6336 ÷ 80 ) x 3.9 x 3.84 = 1186 TPM Cross-
For TPKM ( cable turns per kilometre ) multiply TPM x 0.621
*Centimetres x 0.393 = inches Return to previous page
Morgan
Re-Calibration surcharge