It is important to know how and why you need to inspect drum brakes. Inspecting drum brakes on the vehicles is necessary to ensure their operation and prevent failures from occurring.

We’ll walk you through the process step-by-step and make sure you understand every part of how to measure drum brakes. Just follow this article, and you’ll be well on your way!

How To Measure Drum Brakes?

Step 1

First, remove all of the drum brake components from the wheel. Remove any dirt or grime accumulated on the drums and brake shoes. Depress the star adjuster retention clip with a tiny screwdriver and a small spoon to release it from the brake shoes.

Sometimes you’ll need to use a wrench or another gadget to identify the bolt holding the drum on. Turn the bolt counterclockwise and pull off the drum to remove it. Some drums may require the use of a drum puller to be removed.

Step 2

If your vehicle has a drum brake system, inspect the rotor and make a note of its maximum diameter or size.

Nowadays, most manufacturers use sensors in addition to drums. So you’ll either find a table containing information about this sensor or its substitute, or you’ll refer to charts indicating both maximum diameter and machine-to specifications for disc-brake assemblages used in vehicles from the same manufacturer.

Record any permissible run-out (to assess wear) and make sure to compare measurements to different car types.

Step 3

Place your drum on a level surface with the inside diameter facing up to measure the internal diameter. Examine the condition of the middle of the drum for any signs of fractures or grooves.

Then, inspect the area where the rim meets the inside to verify there are no flakes or chips that might be flung off inside and perhaps harm any micrometer anvils you may be using.

Step 4

Have a micrometer at least 15 inches long when you decide to measure brake drums. For a 10.5-inch length drum, please set it to the 10-inch mark. Next, mark another 10-inch mark and divide the remaining 0.5 inches into four equal parts, along with the original drum.

Step 5

Loosen the lock screw on one of the micrometer’s arms along the shaft. After loosening it, you should be able to move it down the shaft until it rests at 10 inches.

For this measurement, use the actual drum size. If your vehicle’s braking system is a drum, start by setting one side of the micrometer at the 10-inch mark, then measure one side to 10 and four additional inches from there (four marks altogether) to get your 10.5 drum measurement.

Step 6

A depth gauge, sometimes known as a shoe gauge, is an instrument used to measure the thickness of shoes. You may achieve an accurate reading by placing the depth gauge’s tip into an aperture or hole in the shoe.

Use your depth gauge above or beneath the rivet to acquire an accurate measurement while measuring a riveted shoe. Keep an eye on the 2/32 inch since if it’s less than that, it’s time to obtain a new shoe.

How Can You Identify When To Replace Your Drum Brakes? 

A drum brake’s effectiveness depends on how well each shoe can press the outer surface of the drum. The shoes should be as close as possible to the edge of the drum, and they should be in good condition, with no cracks or punctures.

This is the first indicator when you feel vibrations in your foot from the pedal. This signifies that the drums are beginning to wear and time to replace them. The second indicator is pulsing or shuddering from your car, which indicates that your drums are worn out and should be changed as soon as possible because they might fail at any time.


With this information, you now know how to measure drum brakes and what to do to keep your car or truck in good condition. The process is straightforward, but it also needs to be followed appropriately to ensure that the readings provided are accurate. They need to be checked regularly for maximum performance and durability.

We hope you find this post useful. Thank you for reading!

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