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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
are ‘original & complete’... a surcharge may be applied to cover
missing parts etc... If in doubt send in the unit for inspection
‘Good luck with your project’... Enjoy your classic motoring...
If you found this web site via a ‘search engine’ please
check that you are looking @ the latest version... click here
If you found this web site via a ‘search engine’ please
check that you are looking @ the latest version... click here
Jaguar XK 120 ( 1948 / 54 )
182.2M
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: 01535 603570 / Mobile: 07872 071512
Please check the FAQ’s page BEFORE ringing / texting / emailing
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: 01535 603570 / Mobile: 07872 071512
Please check the FAQ’s page BEFORE ringing / texting / emailing
Speedo Calibration... Calculation page
To calculate the new calibration required ( wheel turn method ) use the following formula
( 6336 ÷ A ) x B = TPM ( cable turns per mile ) For TPKM... x TPM by 0.621
A = Circumference of a correctly fitted tyre in inches... (Centimetres x 0.393 = inches)
B = number of speedo cable turns for 20 turns of one wheel ( 10 turns for LSD )
Typical example :
A = 80”... tyre circumference
B = 14.5... speedo cable turns
( 6336 ÷ 80 ) x 14.5 = 1148 TPM
If using the road test method the following formula applies ...
( A ÷ B ) x the present calibration = new TPM where A = your indicated distance & B = true distance
Typical example : A = 9 miles & B = 10 miles.. if the present calibration is say 1000 TPM
the required calibration would be ( 9 ÷ 10 ) x 1000 = 900 TPM
For TPKM ( cable turns per kilometre ) multiply TPM x 0.621
Continued on next page
To calculate the new calibration required ( wheel turn method ) use the following formula
( 6336 ÷ A ) x B = TPM ( cable turns per mile ) For TPKM... x TPM by 0.621
A = Circumference of a correctly fitted tyre in inches... (Centimetres x 0.393 = inches)
B = number of speedo cable turns for 20 turns of one wheel ( 10 turns for LSD )
Typical example :
A = 80”... tyre circumference
B = 14.5... speedo cable turns
( 6336 ÷ 80 ) x 14.5 = 1148 TPM
If using the road test method the following formula applies ...
( A ÷ B ) x the present calibration = new TPM where A = your indicated distance & B = true distance
Typical example : A = 9 miles & B = 10 miles.. if the present calibration is say 1000 TPM
the required calibration would be ( 9 ÷ 10 ) x 1000 = 900 TPM
For TPKM ( cable turns per kilometre ) multiply TPM x 0.621
Continued on next page
Re-Calibration surcharge