How to Measure Drum Brakes
Knowing how to measure drum brakes is extremely important for any driver's safety. Since the drums wear once they reach a certain measurement they are then no longer effective. When the measurement of the drum is off, the power in the breaks is compromised.
Things You'll Need:
- Drum puller
- Drum brake spoon
- Thin screwdriver
- Depth gauge
- Drum and rotor discard specifications chart
- Remove the screws from the hub facing of the drum.
- Take the drum off of the wheel using the drum puller.
- Depress the star adjuster retaining clip using the drum brake spoon and a thin screwdriver.
- Review the outer facing of the rotor.
- Find the stamped maximum diameter.
- Use the drum and rotor discard specifications chart if there is too much rust and corrosion to read the stamped maximum diameter.
- Determine the size of the drum for the specific vehicle, the amount of run-out allowed, the discard specification and the machine-to specification by using the rotor discard specifications chart .
- Put the drum onto a flat surface face down. This will allow the interior diameter of the drum to face upward.
- Inspect the interior of the drum for any cracks.
- Check for any grooves along the surface.
- Loosen the screw on one of the arms along the shaft.
- Measure the actual drive size.
- Put the micrometer anvils into the drum.
- Roll the micrometer back and forth along the inside diameter of the drum.
- Review the dial indicator to detect wear.
- Use several readings and compare the highest measurement.
- Measure the thickness of the shoes.
- Measure several times and use the lowest measurement for the actual reading.