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[Update] How To Measure Drum Brakes?

How To Measure Drum Brakes?

The drum brake comes in many different sizes and is also worn during use. That is why we often have to replace and repair the brake. To do this, the first thing you have to do is measure the thin thickness and brake drum diameter. So, how to measure drum brakes? Check it out in this article below.

What is a drum brake?

The drum brake is also known as the mechanical brake. It used to be a popular brake, especially on small-capacity vehicles such as motorbikes and electric bicycles. Also, nowadays, drum brakes are commonly used in specialized trailers.

With the development of wire compression technology, drum brakes are gradually being replaced by firmer types such as disc, air brake, and ABS brake. However, in vehicles that do not require a high level of safety, drum brakes are still a suitable choice because of their popularity and ease of maintenance.

The drum brake includes a brake drum, brake shoe, brake pad, and other power transmission parts. After a period of use, the drum will expand more than its size, which affects the power and efficiency of the brake. Since then, the risk of causing an accident when in traffic becomes more serious and more dangerous.

When using this type of brake, you must understand its structure and operation mechanism to have a timely remedy when having unexpected problems.

Tool for measuring drum brakes

– Drum puller
– Spoon brake drum
– Screwdriver
– Screw holder
– Caliper for measuring brake drum diameter, micrometer

How to measure drum brake?

Step 1
Remove the drum from the wheel using the drum puller if necessary. Of course, you can de-adjust the shoe by using the drum brake spoon and a thin screwdriver to secure the star regulator clamp. Also, some drum brakes can use a holding screw on the spindle to hold them in place to the shaft. To remove the screws on the shaft before trying to remove the drum.

Step 2
Check the outside of the rotor and locate the maximum stamped diameter or diameter from machine to casting. If the parameter cannot be read due to rust and corrosion, use the drum and rotor rejection specification chart to apply. As you know, each different vehicle has a different way of illustrating the figures, and all you need to do is take the necessary measurements. As follows:

– Determines the size of the drum used on a particular car
– Allowable running amount
– Machine specifications and specifications were removed from the chart.

Step 3
Place the drum face down on a flat surface such that the inside diameter of the drum is facing up. Next, inspect the drum for the above cracks. Also, find spots or grooves along the surface of the inner diameter. If they do appear, the cracks must be treated immediately. Or replace the new drum.

Step 4
Loosen the locking screw on one of the hands along the shaft of the micrometer. The actual drum dimensions are then applied for this measurement. For example, if your vehicle uses a 10.5-inch drum, place one side of the micrometer to the 10-inch mark. In addition to that, set the other arm to 10 inches and add four more 0.125-inch markers along the axis for the 10.5-inch drum.

Step 5
– Place the coils of the micrometer inside the drum.
– Insert them into any applicable points or grooves
– Shake the micrometer back and forth along the inner diameter of the drum.
– See drum readings for unusual wear such as “run out” (out of cycle).

Take some readings and compare the highest measurements. This measurement would have to be added to the 10.5-inch diameter to compare with the machine specifications. From there, you have to determine whether the drum can be machined or must be removed and then replaced.


Hopefully, the article will provide you with useful information on how to measure drum brakes. It is one of the indispensable steps in the brake repair and maintenance process. And above all, to ensure the safety of vehicle users.

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