Ranger 4WD L4-140 2.3L SOHC (1984)
Drum Micrometer
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The measurement should be repeated at 3 or more places around the circumference of the drum to determine if the drum is out of round. If the
measurements differ by more than 0.004 inches the drum should be resurfaced.
NOTE: A drum which is out of round will cause a pedal pulsation to be felt upon braking.
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The measurement should also be repeated at various depths of the drum to check for a bellmouth condition. If the measurements differ by more
than .004 inches the drum should be resurfaced.
NOTE: 1 inch = 25.4mm, so if your micrometer measures in inches and the specified thickness on the disc is in millimeters, convert millimeters
to inches by dividing the specified number of millimeters by 25.4.
Example: Specification on disc is 17.8 mm.
Dividing 17.8mm by 25.4mm/in = 17.8/25.4 = 0.70 inches.
