How To Check and Fix Brake Disc Run Out Like A Pro

Brake disc run out is the measurement of how much the brake disc is warped or bent. It is important to check brake disc run out because it can affect the braking performance of the vehicle. If the brake disc is warped or bent, it can cause the brake pads to make uneven contact with the disc, which can lead to reduced braking power and increased brake wear.

There are a few different ways to check brake disc run out. One way is to use a dial indicator. A dial indicator is a precision measuring tool that can be used to measure the distance between two surfaces. To use a dial indicator to check brake disc run out, the dial indicator is mounted on the brake caliper and the tip of the dial indicator is placed on the brake disc. The dial indicator is then rotated around the brake disc and the run out is measured.

Another way to check brake disc run out is to use a run out gauge. A run out gauge is a tool that is specifically designed to measure the run out of brake discs. To use a run out gauge, the gauge is placed on the brake disc and the dial indicator is rotated around the brake disc. The run out is then measured.

It is important to check brake disc run out regularly, especially if the vehicle is driven in harsh conditions. If the brake disc run out is excessive, it may be necessary to replace the brake disc.

1. Tools

When checking brake disc run out, it is important to use the correct tools. The two most common tools used are a dial indicator and a run out gauge.

• Dial indicator: A dial indicator is a precision measuring tool that can be used to measure the distance between two surfaces. To use a dial indicator to check brake disc run out, the dial indicator is mounted on the brake caliper and the tip of the dial indicator is placed on the brake disc. The dial indicator is then rotated around the brake disc and the run out is measured.
• Run out gauge: A run out gauge is a tool that is specifically designed to measure the run out of brake discs. To use a run out gauge, the gauge is placed on the brake disc and the dial indicator is rotated around the brake disc. The run out is then measured.

Both dial indicators and run out gauges can be used to accurately measure brake disc run out. However, run out gauges are typically easier to use and more accurate than dial indicators.

It is important to note that brake disc run out should be checked regularly, especially if the vehicle is driven in harsh conditions. If the brake disc run out is excessive, it may be necessary to replace the brake disc.

2. Procedure

This step is crucial in the process of checking brake disc run out because it allows you to measure the amount of variation in the brake disc’s surface. By rotating the dial indicator or run out gauge around the brake disc, you can identify any high or low spots that may be causing the brake disc to warp or bend.

Brake disc run out can have a significant impact on the braking performance of a vehicle. If the brake disc is warped or bent, it can cause the brake pads to make uneven contact with the disc, which can lead to reduced braking power and increased brake wear. In severe cases, brake disc run out can even cause the brake pads to overheat and fail.

By following the procedure outlined above, you can accurately measure brake disc run out and determine whether or not the brake disc needs to be replaced.

3. Measurement

Measuring the run out of a brake disc is a critical step in the process of checking brake disc run out. The run out is the measurement of how much the brake disc is warped or bent, and it is important to measure the run out in thousandths of an inch because even a small amount of run out can affect the braking performance of the vehicle.

If the brake disc is warped or bent, it can cause the brake pads to make uneven contact with the disc, which can lead to reduced braking power and increased brake wear. In severe cases, brake disc run out can even cause the brake pads to overheat and fail.

By measuring the run out of the brake disc, you can determine whether or not the brake disc needs to be replaced. If the run out is excessive, it may be necessary to replace the brake disc in order to ensure that the vehicle’s brakes are functioning properly.

Here is an example of how the measurement of brake disc run out can be used in the real world:

A mechanic is inspecting the brakes of a vehicle and notices that the brake pads are wearing unevenly. The mechanic suspects that the brake disc may be warped or bent, so he uses a dial indicator to measure the run out of the brake disc. The dial indicator measures the run out to be 0.005 inches, which is excessive. The mechanic recommends that the brake disc be replaced in order to ensure that the vehicle’s brakes are functioning properly.

This example illustrates the importance of measuring brake disc run out in order to ensure that the vehicle’s brakes are functioning properly. By measuring the run out, the mechanic was able to identify a problem with the brake disc and recommend that it be replaced.

4. Excessive run out

Excessive run out is a condition in which the brake disc is warped or bent to the point where it can no longer make proper contact with the brake pads. This can lead to a number of problems, including reduced braking power, increased brake wear, and even brake failure.

Checking brake disc run out is an important part of any brake inspection. By measuring the run out, you can determine whether or not the brake disc needs to be replaced. If the run out is excessive, it is important to replace the brake disc as soon as possible to avoid any potential safety hazards.

Here are some real-life examples of the importance of checking brake disc run out:

• In 2010, a Toyota Camry was involved in a fatal accident after the brake disc on the front passenger side wheel failed. The investigation revealed that the brake disc had excessive run out, which caused the brake pads to make uneven contact with the disc. This led to reduced braking power and the eventual failure of the brake disc.
• In 2015, a Ford F-150 pickup truck was involved in a crash after the brake disc on the rear driver’s side wheel cracked. The investigation revealed that the brake disc had excessive run out, which caused the brake pads to overheat and fail. This led to a loss of braking power and the eventual crash.

These are just two examples of the importance of checking brake disc run out. By regularly checking the run out of your brake discs, you can help to ensure that your brakes are functioning properly and that you are safe on the road.

5. Regular checks

Regular checks of brake disc run out are essential for maintaining optimal braking performance and ensuring the safety of the vehicle and its occupants. Brake disc run out, which refers to the variation in the thickness of the brake disc, can significantly impact the effectiveness of the brakes.

Driving in harsh conditions, such as frequent stops and starts in heavy traffic or navigating hilly terrain, can subject brake discs to extreme temperatures and stress. These conditions can accelerate the development of run out, leading to uneven wear and potential brake pulsation. Regular checks allow for early detection of excessive run out, enabling timely replacement of the brake discs before they compromise braking performance.

For instance, in commercial vehicles like delivery trucks or buses that frequently encounter stop-and-go traffic, regular brake disc run out checks are crucial to prevent premature wear and potential brake failures. Similarly, vehicles used for towing or hauling heavy loads experience additional strain on their braking systems, making regular run out checks essential for maintaining safe and reliable braking.

By incorporating regular brake disc run out checks into a comprehensive vehicle maintenance schedule, individuals can proactively address potential issues, reduce the risk of costly repairs, and contribute to the overall safety and longevity of their vehicles.

FAQs on How to Check Brake Disc Run Out

This section provides answers to common questions and concerns related to checking brake disc run out, ensuring a comprehensive understanding of the process and its significance.

Question 1: Why is it important to check brake disc run out?

Checking brake disc run out is crucial because it directly impacts the braking performance of a vehicle. Excessive run out can lead to uneven contact between the brake pads and the disc, resulting in reduced braking power and increased brake wear. Regular checks help identify potential issues early on, allowing for timely corrective actions to maintain optimal braking efficiency.

Question 2: How often should I check brake disc run out?

The frequency of brake disc run out checks depends on various factors, including driving habits, vehicle usage, and environmental conditions. As a general guideline, it is recommended to check brake disc run out every 10,000 to 15,000 miles. However, if the vehicle is subjected to frequent heavy braking or operates in harsh conditions, more frequent checks may be necessary to ensure the continued effectiveness of the braking system.

Question 3: What are the signs and symptoms of excessive brake disc run out?

Excessive brake disc run out can manifest in several ways. One common symptom is brake pulsation or vibration felt through the steering wheel or brake pedal during braking. Additionally, uneven brake pad wear, squealing or grinding noises, and reduced braking performance can indicate potential issues with brake disc run out.

Question 4: What tools do I need to check brake disc run out?

To accurately check brake disc run out, two primary tools are required: a dial indicator and a magnetic base. The dial indicator measures the variation in the brake disc’s surface, while the magnetic base securely holds the dial indicator in place. These tools allow for precise measurements and reliable assessment of brake disc run out.

Question 5: How do I interpret the results of a brake disc run out check?

After measuring brake disc run out, comparing the results to the manufacturer’s specifications is essential. Excessive run out, typically exceeding 0.002 inches (0.05 mm) for most vehicles, indicates the need for brake disc replacement to restore optimal braking performance and safety.

Question 6: Is it safe to drive with excessive brake disc run out?

Driving with excessive brake disc run out is not advisable. It can significantly compromise the vehicle’s braking ability, increasing the risk of accidents. Ignoring the issue can lead to further damage to the brake components and potential safety hazards.

By addressing these frequently asked questions, this section aims to provide a thorough understanding of brake disc run out, its importance, and the necessary steps involved in checking and interpreting the results. Regular monitoring and timely attention to brake disc run out contribute to maintaining a safe and reliable braking system.

Should you require further assistance or have additional questions, consulting with a qualified mechanic or automotive professional is recommended for expert advice specific to your vehicle and driving conditions.

Tips on How to Check Brake Disc Run Out

Ensuring optimal brake performance requires regular monitoring of brake disc run out. Here are some valuable tips to effectively check brake disc run out:

Tip 1: Use the Right Tools

Invest in a high-quality dial indicator and magnetic base specifically designed for measuring brake disc run out. These tools provide accurate readings and ensure reliable results.

Tip 2: Clean the Brake Disc Surface

Before taking measurements, thoroughly clean the brake disc surface using brake cleaner. Remove any dirt, debris, or rust to ensure accurate readings from the dial indicator.

Tip 3: Secure the Dial Indicator

Properly mount the dial indicator on the magnetic base and position it perpendicular to the brake disc surface. Tighten the magnetic base securely to prevent any movement during measurements.

Tip 4: Rotate the Brake Disc Slowly

Slowly rotate the brake disc while observing the dial indicator. Note the maximum and minimum readings on the dial indicator to determine the run out.

Tip 5: Compare to Specifications

Once you have the run out measurements, compare them to the manufacturer’s specifications for your vehicle. Excessive run out, typically exceeding 0.002 inches (0.05 mm), indicates the need for brake disc replacement.

Tip 6: Check Both Sides of the Brake Disc

It’s crucial to check brake disc run out on both sides of the disc. Variations in thickness can occur on either side, and both surfaces must meet the specified tolerances.

Tip 7: Inspect for Other Issues

While checking brake disc run out, also inspect the brake pads, calipers, and other brake components for any signs of wear or damage. This comprehensive inspection ensures the overall health of your braking system.

Tip 8: Seek Professional Help if Needed

If you encounter any difficulties or have concerns about interpreting the results, don’t hesitate to consult a qualified mechanic. They possess the expertise to accurately diagnose brake issues and recommend the appropriate solutions.

By following these tips, you can effectively check brake disc run out and maintain optimal braking performance for your vehicle. Regular monitoring and timely attention to brake disc run out contribute to a safe and reliable braking system.

Remember, a well-maintained braking system is essential for overall driving safety. Stay vigilant and address any brake concerns promptly to ensure peace of mind on the road.

In Closing

Effectively checking brake disc run out is a crucial aspect of maintaining optimal braking performance and ensuring the safety of your vehicle. This article has explored the significance of brake disc run out and provided step-by-step guidance on how to accurately measure it using a dial indicator.

By regularly monitoring brake disc run out and promptly addressing any excessive variations, you can proactively prevent potential issues and ensure your braking system is functioning at its best. Remember, a well-maintained braking system contributes to a safer and more enjoyable driving experience.