FAQ - Spedometer Calibration
#1
FAQ - Spedometer Calibration
From the 73-79 FAQ. Calibration formulas, methods & procedures, speedometer gears are discussed and/or linked to.
Provided by @Torque1st
Speedometer Calibration
Here are links to good speedometer calibration methods:
https://www.ford-trucks.com/forums/sh...hreadid=179955
https://www.ford-trucks.com/calculato...trument_error/
And a speedometer calibration re tire size re... calculator:
https://www.ford-trucks.com/calculato...php/p-mph_rpm/
More calculators:
https://www.ford-trucks.com/calculators/index.php
FTE also has CLASSIFIED ADS for buying and selling vehicles and parts.
Formula for instrument error:
------------------------------------
Calculator here:
https://www.ford-trucks.com/calculato...trument_error/
Manual methods for old folks:
actual mph = 3600 / seconds per mile
speedo error percent =
difference between actual and indicated speed / actual speed x 100
indicated distance =
odometer reading at finish - odometer reading at start
odo error percent =
difference between actual and indicated distances / actual distance x 100
Seconds to travel ONE measured mile:
==================================
Time= Actual road speed
50=72
51=71
52=69
53=68
54=67
55=65
56=64
57=63
58=62
59=61
60=60
61=59
62=58
63=57
64=56
65=55.4
66=54.5
67=54
68=53
69=52
NOTE- Time your vehicle over a 10 mile distance for ease and accuracy.
Speedometer gear replacement:
-----------------------------------------
REMOVE the original driven gear.
Ts = Number of teeth on service driven gear.
To = Number of teeth on original driven gear.
Va = Actual vehicle speed.
Vi = Indicated vehicle speed.
VSS = Vehicle Speed Sensor.
NOTE: Design accuracy is: -2/+5 mph at 30 and 60 mph
(-3/+8 km/h at 50 and 100 km/h).
NOTE: Use one of the following formulas:
-------------
With Va, Vi, and To known, calculate new number of driven rear teeth.
Ts = (Vi x To)/Va
Ts = (To x new tire revolutions per mile)/(old tire revolutions per mile)
Round to whole number, dropping fractions less than .6, and rounding up if
fraction is .6 or higher.
Provided by @Torque1st
Speedometer Calibration
Originally Posted by Torque1st
Here are links to good speedometer calibration methods:
https://www.ford-trucks.com/forums/sh...hreadid=179955
https://www.ford-trucks.com/calculato...trument_error/
And a speedometer calibration re tire size re... calculator:
https://www.ford-trucks.com/calculato...php/p-mph_rpm/
More calculators:
https://www.ford-trucks.com/calculators/index.php
FTE also has CLASSIFIED ADS for buying and selling vehicles and parts.
Formula for instrument error:
------------------------------------
Calculator here:
https://www.ford-trucks.com/calculato...trument_error/
Manual methods for old folks:
actual mph = 3600 / seconds per mile
speedo error percent =
difference between actual and indicated speed / actual speed x 100
indicated distance =
odometer reading at finish - odometer reading at start
odo error percent =
difference between actual and indicated distances / actual distance x 100
Seconds to travel ONE measured mile:
==================================
Time= Actual road speed
50=72
51=71
52=69
53=68
54=67
55=65
56=64
57=63
58=62
59=61
60=60
61=59
62=58
63=57
64=56
65=55.4
66=54.5
67=54
68=53
69=52
NOTE- Time your vehicle over a 10 mile distance for ease and accuracy.
Speedometer gear replacement:
-----------------------------------------
REMOVE the original driven gear.
Ts = Number of teeth on service driven gear.
To = Number of teeth on original driven gear.
Va = Actual vehicle speed.
Vi = Indicated vehicle speed.
VSS = Vehicle Speed Sensor.
NOTE: Design accuracy is: -2/+5 mph at 30 and 60 mph
(-3/+8 km/h at 50 and 100 km/h).
NOTE: Use one of the following formulas:
-------------
With Va, Vi, and To known, calculate new number of driven rear teeth.
Ts = (Vi x To)/Va
Ts = (To x new tire revolutions per mile)/(old tire revolutions per mile)
Round to whole number, dropping fractions less than .6, and rounding up if
fraction is .6 or higher.
Last edited by ctubutis; 11-11-2018 at 09:09 PM. Reason: No more HTML tags
Thread
Thread Starter
Forum
Replies
Last Post