How To Use a Dial Indicator to Check Rotor Runout?

Rotor runout is a common issue with electric motors and can lead to decreased performance and even potential failure of the motor. There are several ways to check rotor runout, but one of the simplest methods is to use a dial indicator.

This device uses an adjustable pointer to measure how much play or slop there is in the rotors on your motor shafts. If there is excessive play or slop, it may be indicative of rotor runout and should be fixed as soon as possible. 

Dial indicators are relatively inexpensive tools that you can find at most hardware stores or online retailers, so don’t hesitate to get started checking your motors.

How To Use a Dial Indicator To Check Rotor Runout

If you’re having trouble starting your car, one common cause is a worn or damaged rotor. 

Dial Indicator To Check Rotor Runout
Dial Indicator To Check Rotor Runout

A dial indicator can help you check the rotors for runout, and if needed, replace them. Here’s how to use it:

How To Use a Dial Indicator

A dial indicator is a simple device that can be used to check rotor runout. Rotor runout is the amount of wear on your engine’s rotors. This issue can result in reduced fuel efficiency and decreased performance. 

How To Use a Dial Indicator
How To Use a Dial Indicator

Checking rotor runout with a dial indicator can help you identify any problems early on and fix them before they become bigger issues.

The Parts of a Dial Indicator

The parts of a dial indicator include the handle, pointer, and gauge plate. The handle allows you to move the pointer around the gauge plate, which displays the amount of worn or missing rotors.

The Parts of a Dial Indicator

How To use it

To use a dial indicator, first find out how much wear your engine has on its rotors by checking for rotor runout using an appropriate tool such as an agitator tester or torque wrench. 

Once you have determined how much wear your engine has set up your dial indicator according to these steps: 

The Parts of a Dial Indicator
The Parts of a Dial Indicator
  1. Holding it so that it’s level
  2. Placing one end against one corner of the wheel hub
  3. Turning until resistance is felt (the pointer should now indicate how far away from the center each wheel/rotor is
  4. Repeat this procedure on each side If there are any missing or worn components, replace them immediately.

How to Measure a Rotor Runout

If you’re ever having trouble with your car, one of the first things to check is the rotor runout. 

Measure a Rotor Runout
Measure a Rotor Runout

This is a measurement of how far the rotors are from their hub on each side. If they’re too worn or damaged, this can cause vibrations and other problems with your car’s engine.

Remove the Brake Pedal and Floor Board

When checking rotor runout, it is important to remove any obstacles that could get in the way of measurement. This includes removing the brake pedal and floor board.

Remove the Brake Pedal and Floor Board
Remove the Brake Pedal and Floor Board

Measure The Rotor Runout at Two Points on the Hub

To measure rotor runout, you will need to take two measurements at different points along the hub of your wheel (as shown in figure A). 

Make sure that both measurements are taken from a location where there is no wear or damage on the rotor surface (for example: not near calipers or braking surfaces).

Use a Caliper Tool to Check for Tread Wear Damage

If you notice excessive treadwear damage on one or more rotors, this may indicate an issue with your brakes and should be inspected accordingly.

In order to check for treadwear damage using a caliper tool, simply place the gauge across several spots around each tire’s circumference.

Maintenance Tips on Brake Rotors

If you’re like most people, you probably don’t think much about your brake rotor. But if the rotor isn’t running true, it can cause problems with braking performance. To check your rotor runout, use a dial indicator.

Checking rotor runout

A dial indicator is a simple tool that can be used to measure the runout of brake rotors. This measurement is important because it helps determine if your brakes need to be replaced.

Why measuring rotor run out is important

Measuring the amount of runout on your brake rotors allows you to know how much wear and tear they have experienced over time. 

Lack of proper running may cause your brakes not to work as efficiently, which in turn could lead to serious safety hazards.

The types of indicators that you can use for this purpose

There are a number of different types of indicators available, so depending on what type you have at hand, you can easily take measurements on your own or have someone else do it for you.

Precautions when using an indicator like this

Before taking any measurements, make sure that all applicable braking systems are properly operational and calibrated before starting the test process – otherwise inaccurate readings might result from incorrect assumptions about system performance levels.


What Is Acceptable Runout on Brake Rotors?

The acceptable runout on brake rotors is typically no more than .001 inches.

Which Tool Is Used to Measure the Lateral Runout of a Rotor?

The lateral runout is measured using a dial indicator.

What Is Excessive Brake Disc Run Out?

Excessive brake disc runout is when there is too much wear on the brake discs or rotors. This can cause the brakes to stop working properly, or even cause a car accident.

What Is the Minimum Thickness of Brake Rotor?

The minimum thickness of the brake rotor is 2 to 3 mm.

Which Tool Is Used to Measure the Thickness of a Brake Rotor?

A caliper is used to measure the thickness of a brake rotor.


Checking rotor runout is an important part of maintaining your car and can help ensure a safe drive. There are different ways to check rotor runout, and the dial indicator is one of the most common.

The dial indicator measures how far the main shaft has traveled from its hub in a particular direction. Rotor runout can be caused by wear on the main shaft or bearing, so it’s important to keep an eye on it as you drive your car safely.

By checking rotor runout regularly, you can prevent any mechanical issues that could lead to crashes or injuries in flight.

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