How to Measure Brake Drum Out of Round

How to Measure Brake Drum Out of Round

Brake drums are essential components of a vehicle's braking system, providing the necessary friction to slow down or stop the car. Over time, these drums can wear unevenly, leading to a condition known as out of round. This occurs when the drum's internal surface is not perfectly circular, resulting in inconsistent contact with the brake shoes and potentially compromising braking performance. It's crucial to regularly check and measure the brake drums to ensure optimal safety and functionality. Here’s how to measure brake drum out of round effectively.

Tools Required

To measure a brake drum for out-of-round conditions, you will need a few basic tools 1. Caliper Gauge - For measuring the diameter of the drum at various points. 2. Dial Indicator - To detect variations in the drum's surface and alignment. 3. Micrometer - For precise measurement of the drum’s thickness. 4. Ruler or Tape Measure - To assist with basic measurements.

1. Preparation Begin by safely lifting the vehicle on a level surface and securing it with jack stands. Remove the wheel and brake drum to expose the brake components.

2. Initial Visual Inspection Before taking measurements, inspect the drum for any visible signs of damage or excessive wear. If the surface looks scored or pitted, it may need replacement.

3. Measure the Diameter Using a caliper gauge, measure the diameter of the drum at several points around the circumference. It’s essential to take measurements at various locations — both horizontally and vertically — to determine if there is any irregularity. Record your measurements for comparison.

4. Check for Out of Round Attach the dial indicator to a stable part of the brake assembly, ensuring that the probe makes contact with the surface of the drum. Slowly rotate the drum while observing the dial indicator. Any deviation from zero indicates a variance from the ideal roundness. Note the highest and lowest readings; the difference between these values will give you the out-of-round measurement.

5. Measure Drum Thickness Utilize a micrometer to measure the drum’s thickness in several locations. This is important because excessive wear can further compound out-of-round conditions.

6. Evaluate Your Findings Once you have all your measurements, assess the out-of-roundness. Typically, an out-of-round measurement exceeding 0.005 inches may require the drum to be machined or replaced, depending on manufacturer specifications. Likewise, check the thickness to confirm it has not fallen below the minimum allowable clearance, which could also warrant replacement.

Conclusion

Measuring the out-of-round condition of brake drums is vital for maintaining vehicle safety and braking efficiency. Regular checks can prevent uneven wear and restore optimal drum condition, ensuring effective braking performance. If significant out-of-roundness is detected, consider consulting a professional mechanic for further evaluation and potential resurfacing or replacement of the drum. Regular maintenance will not only prolong the life of your braking system but also ensure your safety on the road.