Brake drum measurement sounds very complicated. Fortunately, you do not need a degree in mechanical engineering or math to do this job. You can measure your car’s brake drums yourself. And measuring this is not rocket science at all. So, how to measure brake drums by yourself?
We all know how essential a break is in an emergency. Before an accident, even one second can make the determining factor between survival and failure. To ensure your safety, you should inspect the brake regularly. Drums are one of the foremost crucial parts of brakes.
However, if the brake drums are not perfect, they will make extra noise during the break and not work properly. Make sure that the brake drums are the right size periodically. Nevertheless, there’s no point in taking it to a mechanic and spending additional money. Because you can do it, it’s just a piece of cake.
How To Measure – You Should Be Know
Using A Digital Micrometer
Step1
 Grasp the tire carefully and unscrew it from the car. Now open the bolts, detach the drums from the brake drums, and carry off the drums from the axle.
 It is good practice to keep the brake drums on a solid surface.
 Usually, there is a maximum and minimum size for each drum. You need to measure how close it is to the maximum or minimum. Drums with smaller diameters are better. To figure out what the optimum length is for your drums, visit the manufacturer’s website.
 Alternatively, look at the outside of your brake drums since many drums have the optimum length written on them.
Step2
 After you have determined the maximum size, you will need to measure it. To measure, you need a measuring device. Its name is Durum Caliper micrometer. They are accessible in two versions, digital and analog.
 Our recommendation would be to use a digital micrometer. It is more convenient to use. However, if your analog micrometer already exists, you can skip step3.
 The Durum Caliper micrometer has a digital display that shows measurements. Two metal rods are for measuring. At this time, we will use the internal gauge.
 As of now, you know what the maximum diameters are. There are two ways of measuring diameter: millimeters and inches. Make sure your micrometer is set to the measuring technique you are applying. The micrometer can be easily switched to millimeters and inches.
Step3
 Set the micrometer to zero now. Set it up to the maximum diameter of the brake drums.
 Our next task is to measure the diameters of brake drums. Circular diameters intersect the circle’s centers and separate them into two equal parts. Currently, we can’t realize where the drums’ center is. Therefore, we will insert the micrometer measurement inside the drums and set the maximum size allowed by the volume.
 After that, we will hold one side of the micrometer while moving the other side from right to left. By moving left and right, we will observe where I get the maximum length. Be sure to write it down.
 In the same way, we will measure the brake drums again from the horizontally opposite side of where I took the first measurement. Be sure to note the maximum size.
 We have completed the measurement process. Our next step is identifying your brake drums to make sure they are correct based on their shape.
Using An Analog Micrometer
The analog micrometer is a good buy but a bit difficult to use. However, we’ve simplified the process for you. Follow the first and second steps mentioned earlier.
Step1
Your first task is to configure your analog micrometer. Therefore, you need to know the minimum size of your Brake Drums. Suppose your drums have a minimum length of 9 inches. Now, move the metal rod to the place where the number 9 is written on the micrometer. Make things worse there. On the other side, set up the other metal rod at 9 too.
Additional Tips: In cases where drum sizes are given in millimeters, which should convert them to inches. Because analog micrometers are measured in inches, you will get an inch if you multiply a millimeter by 0.03937.
Step2
Now insert the micrometer inside the drums. Follow the same lefttoright flow as before. The micrometer displays an analog meter similar to a clock. As you move left to the right, the meter will move. You should note down the optimal reading spot.
Now it is time to do some math. Add the maximum reading on the meter to the length you selected earlier. As an example, we said that we set the metal rod at 9 inches. Add 9.00 to the readings found in meters. Once this is done, we can determine the drums’ diameter. Take a horizontal measurement of the width of the drums from the other side using the same process.
Identify The Measurement
We have taken the measurement. Our next step is to determine whether it is OK. You can do this very easily. There are two things to remember here. To begin with, we need to check whether the diameters of both sides are equal and whether the maximum limit has been crossed.
Maximum Limit  Condition  
1  The diameters are equal on both sides  Lenth is less than the maximum level  There is no damage to the brake drums. 
2  The diameters are equal on both sides  Lenth is more than the maximum level  Brake drums are no longer usable. You should buy a new one.

3  Diameters are not equal on both sides  Lenth less than the maximum level  The brake drums are not a perfect circle in size. Drums need to be adjusted by a mechanic. You don’t require to replace them. 
4  Diameters are not equal on both sides  Lenth more than the maximum level  Break drums are not suitable for use. Purchase and install new brake drums.

You can determine the current condition of your brakes by looking at the chart. Follow the instructions in the condition. We welcome all questions, so don’t be afraid to ask.
Conclusion
I hope now you know how to measure brake drums by yourself.