Explained in this article, Lateral Run-out (or simply run-out) is a measure of how much off-centre a brake rotor is as it spins around the hub. A vibration, or pulsing, in your brake pedal or steering wheel when your apply your brakes may indicate that your run-out is off tolerance. In this article, we will go over how to check it.
How to properly measure rotor runout?
- Next, we are going to measure runout 10mm (0.4 in.) from the outer edge on a smooth flat portion of the rotor. ...
- Place the dial indicator needle against the rotor.
- Next, find the lowest spot on the brake rotor by rotating it slowly a full 360 degrees circle. ...
How much runout allowed on rotors?
The maximum allowable runout at the rotor friction surface is 0.002 inch (0.050 mm) as stated by most manufacturers. Shimming the Rotor Flange runout can be corrected with tapered shims that are available to correct a runout of 0.003inch (0.075 mm) to 0.009 inch (0.230 mm) A runout of more than 0.005 inch (0.125 mm) at the bearing flange cannot be corrected by the use of a shim.
What you should know about brake rotors?
There are three main types of brake rotors:
- Conventional: These are typically solid iron, and are suitable for most normal, everyday consumer applications.
- Drilled: These rotors have holes drilled clean through them in order to diffuse heat. ...
- Slotted: These brake discs have grooves – or channels – that allow for some heat dissipation as well as serve to keep the brake pads cleaner. ...
How to resurface a motorcycle brake rotor?
How to Replace a Motorcycle Brake Rotor
- Buy the Correct Brake Rotor. There are different types of rotor brakes available in the market. ...
- Place Bike in Safe Position. Ensure the bike is positioned safely before carrying out any kinds of repair. ...
- Locate Brake Rotors. ...
- Replace the Brake Rotor. ...
- Tips. ...
What is acceptable rotor runout?
The maximum allowable runout at the rotor friction surface is 0.002 inch (0.050 mm) as stated by most manufacturers.
How do you check brake rotors runout?
3:106:29How to Properly Measure Rotor Runout - YouTubeYouTubeStart of suggested clipEnd of suggested clipTo check run-out mount the dial indicator to a fixed point on the steering knuckle. The needle ofMoreTo check run-out mount the dial indicator to a fixed point on the steering knuckle. The needle of the dial indicator should be perpendicular to the brake rotor measurement.
What is excessive runout on rotors?
Lateral runout is the side to side movement of the brake rotor as it rotates. When this gets excessive, pad and rotor wear will result. This excessive movement will result in vibration and pulsation in the steering wheel or seat of a vehicle.
What causes brake runout?
Lateral runout may be caused by uneven torque on a brake stud. However, the most common cause of lateral runout is rust buildup on the hub assembly. Hubs are often in use on a vehicle for hundreds of thousands of miles. As you can imagine, a significant amount of rust will build up on that hub over that period of time.
What is the minimum rotor thickness?
Brake rotors are marked with a “minimum thickness” on the casting (usually 2 mm to 3 mm less than the new rotor thickness). Rotors should be replaced before they reach this minimum thickness and should not be “turned” (machine refinished) below this.
How do I know if my rotors are warped?
1:333:18How to Check a Rotor for Warpage - YouTubeYouTubeStart of suggested clipEnd of suggested clipNow rotate the rotor. And watch the dial as you can see the dial has a fine movement. And we're onlyMoreNow rotate the rotor. And watch the dial as you can see the dial has a fine movement. And we're only seeing about one thousandth of run-out. Just as an extra example. You will see the dial movement.
How is runout measured?
Runout is measured using a simple height or dial gauge. We fix the part by means of a V-block or a spindle along its datum axis. The pin of a dial gauge is then set on the circular feature and the dial is set to zero. We now rotate the CNC machined part along the spindle and record the measurements.
When should a grooved brake rotor be replaced?
A. The only time you'll need to replace your brake pads and rotors is when the pads are worn and your rotors are warped, though that doesn't happen often. Rotors are engineered to last about 50,000-80,000 miles for standard steel. Carbon-ceramic discs will last longer.
How often should you flush brake fluid?
every 2 yearsOn average, you will need a brake fluid flush every 2 years or 30,000 miles. Routine maintenance also heavily depends on your driving patterns. For example, if you tend to drive shorter routes with frequent braking, you may need more frequent brake fluid flushes.
How do you measure thickness and run out of brake discs?
1:544:39How to measure Brake Rotor Lateral Runout and Minimum ThicknessYouTubeStart of suggested clipEnd of suggested clipIn a safe position. So that we don't stress the hose never let a caliper hang on its hose it willMoreIn a safe position. So that we don't stress the hose never let a caliper hang on its hose it will destroy the hose. Now let's measure the thickness of our brake rotor. Always zero out your micrometer.
Why do we measure rotors?
Brake rotor thickness is a crucial measurement for your vehicle's safety. It is important to know your vehicle's minimum brake rotor thickness because if the rotor is thinner than the minimum thickness, it can be dangerous to operate. Thinner rotors are lighter in weight and less able to absorb and dissipate heat.
What are 2 causes of rotor thickness variation?
Common causes of DTV: A few of the more common causes resulting in DTV are: Wheel nut torque. Variations in torque values causing distortion of the disc rotor and hub.
How do you measure thickness and run out of brake discs?
1:544:39How to measure Brake Rotor Lateral Runout and Minimum ThicknessYouTubeStart of suggested clipEnd of suggested clipIn a safe position. So that we don't stress the hose never let a caliper hang on its hose it willMoreIn a safe position. So that we don't stress the hose never let a caliper hang on its hose it will destroy the hose. Now let's measure the thickness of our brake rotor. Always zero out your micrometer.
How do you measure rotor runout with dial indicator?
0:333:07Chapter 4: Using the Dial Indicator - YouTubeYouTubeStart of suggested clipEnd of suggested clipReading is the lowest spot on the rotor. Once you determine the low spot gently push the gauge toMoreReading is the lowest spot on the rotor. Once you determine the low spot gently push the gauge to bring the needle to top dead center or pointing towards the rotor.
What is maximum disc run out?
To confirm that the brake disc is in alignment, a run out measurement was taken to eliminate the brake disc as a source of misalignment. The maximum amount of tolerance for brake disc runout is >0.08mm.
How do you measure rotor thickness?
To measure your rotor's minimum operational thickness, place a micrometer at the thinnest point on the rotor's surface where it meets the brake pads. If your rotor has worn past this thickness or needs to be cut, you need new rotors.
What causes judder on a rotor?
There are only two causes for judder — lateral runout and disc thickness variation on the rotor’s friction surface. Advertisement. What could have caused the lateral runout? The causes of the condition range from lugs that were over or unevenly torqued to common corrosion between the hub and rotor.
Why do lateral runouts come back?
The greatest cause of lateral runout comebacks is not poor OEM engineering or low-quality aftermarket parts, it is ignorance and carelessness. Don’t take this the wrong way, but some of your instincts and methods of operation could be costing you. By no means, is this written from from the perspective of talking down to the technician, it is just some self-introspection can even help the best technician. Take the time to perform a diagnostic on yourself. You might be surprised.
What is the J 42450A wheel hub cleaning kit?
Clean all of the mating surfaces between the hub, the rotor and the wheel using the J 42450A — Wheel Hub Cleaning Kit if rotors are not to be refinished.
How many inches can a flange run out be corrected?
Flange runout can be corrected with tapered shims that are available to correct a runout of 0.003inch (0.075 mm) to 0.009 inch (0.230 mm) A runout of more than 0.005 inch (0.125 mm) at the bearing flange cannot be corrected by the use of a shim.
Where is the minimum thickness on a rotor?
Reference the minimum thickness specification stamped on the backside of the rotor or SI for Minimum Thickness specification/other. In most cases, the rotor should be refinished unless the measurement taken makes it obvious that refinishing the rotor would take the measurement under the Minimum Thickness specification (then replacement is necessary).
What is bearing end play?
Check bearing end play: End play is an indication of bearing condition and adjustment.
How to mount all wheels?
All wheels should be mounted by using a crossing pattern to tighten the lugs.
What causes a hub to run out?
Hub face run out can be the root cause but the most common condition causing the problem is rust and scale between the hub face and the inside of the rotor hat.
Why do rotors wobble?
What does happen is that rotors will have excessive run out or wobble because they are not operating a right angle in relationship to the hub face. What this means is that every time a portion of the rotor comes around the rotor makes some contact with the pads and wears the rotor thickness away at that point.
Why does my bike pedal pulsate?
The cause of pedal pulsation shouldn’t be a mystery. In addition to checking the rotor run out and rotor thickness variation it is also recommended that you set up your dial indicator and take run out of the hub face. This is easier said than done as the studs make setting up the dial indicator to take a hub run out reading all but impossible.
Why do you need grease on a hub?
Many technicians along with others recommend applying some grease or anti-size to the hub face to help prevent future rust and scale build up. Some OE manufactures do and have used a lubricant at this location for years while others do not.
Can disc brakes warp?
Many people believe that disc brake rotors can warp during normal service. Tales sometimes, even told by OE Dealerships, will state that you should not apply your brakes. They will also tell you not to drive through a deep puddle when it’s raining because if the rotor is hot from hard application and then gets drenched, it will warp. One national brake trainer’s daughter was actually told this when she brought her new, under warranty, vehicle in because of a pedal pulsation problem.
Can rotor run out cause pedal pulsation?
There are specifications published that identify the allowable amount of rotor run out but any run out that causes a pedal pulsation condition is excessive.
What is rotor runout?
Rotor Lateral Runout. Lateral runout is the side to side movement of the brake rotor as it rotates. When this gets excessive, pad and rotor wear will result. This excessive movement will result in vibration and pulsation in the steering wheel or seat of a vehicle.
How to measure lateral runout?
Measure lateral runout with a dial indicator. If it is excessive, use an outside micrometer to measure the thickness of the rotor and compare it to the minimum thickness stamped on the rotor. This process is checking the rotor for parallelism. Check at least eight different spots around the rotor to find the thinnest spot.
Why do lateral runouts come back?
The greatest cause of lateral runout comebacks is not poor OEM engineering or low-quality aftermarket parts, it is ignorance and carelessness. Don’t take this the wrong way, but some of your instincts and methods of operation could be costing you. By no means is this written from the perspective of talking down to the technician, it is just some self-introspection can even help the best technician. Take the time to perform a diagnostic on yourself. You might be surprised.
What could have caused lateral runout?
What could have caused the lateral runout? The causes of the condition range from lugs that were over or unevenly torqued to common corrosion between the hub and rotor. There are other causes, such as the rotor machined to less-than-minimum thickness and overheating.
What happens if you change the rotor 180°?
Changing the rotor position 180º on the bearing can check flange runout. If the high spot changes 180º, the rotor could be OK or ready to turn after the bearing is shimmed. Advertisement. Components should be marked as you perform an inspection of the assembly. Check the bearing endplay.
How many inches can a flange run out be corrected?
Flange runout can be corrected with tapered shims that are available to correct a runout of 0.003 inch (0.075 mm) to 0.009 inch (0.230 mm) A runout of more than 0.005 inch (0.125 mm) at the bearing flange cannot be corrected by the use of a shim.
What is bearing end play?
Check bearing end play: End play is an indication of bearing condition and adjustment.
How to mount all wheels?
All wheels should be mounted by using a crossing pattern to tighten the lugs.
Do you check rotor runout before installing wheel?
Check new rotor runout: It’s a double check before installing the wheel.
How to measure runout on rotor?
Set the dial indicator on its stand and position it on the rotor for a reading. Make sure the gauge is at “0.” Turn the rotor and the dial indicator will measure runout. If the measurement fluctuates any more than 4/1000th (0.004) of an inch, you should replace the rotors.
What is a brake rotor made of?
Brake rotors are made of cast iron and are subject to runout. When the car is engaged, the brake pad is pressed against the rotor. The heat and friction that occurs during this process is absorbed by the rotor. Heat is caused by friction and can cause your rotor to wear out over time. The performance of the rotor is directly related to the performance of the brakes. Here are a few simple steps you can take to check your rotor for runout.
Why measure runout on brakes?
You should measure runout every time you remove the wheels and brake rotors as a preventative measure to save yourself a lot of time and money. Excessive runout will cause uneven rotor wear or warpage. Brake rotor warpage may cause a brake pedal pulsation or steering wheel vibration when applying brakes. You may also get a BRAKE warning light on ...
What to do when disc rotor runout exceeds maximum?
When runout exceeds the maximum value, try to change the installation position of the disc rotor so that the runout will become minimal. If the runout exceeds the maximum allowed value even when the installation position was changed, remove the brake rotor and check for bearing looseness and the bearing hub runout.
How to tighten brake rotor after removing caliper?
After removing the brake caliper we are going to tighten the brake rotor using wheel lug nuts.
What is the maximum runout for a car?
The maximum runout for most cars should not exceed 0.002 in (0.05 mm). On my car there runout was 0.004 inch. This explains why my brake pedal was pulsating and the steering wheel was vibrating when applying brakes.
Where is the brake warning light on a car?
You may also get a BRAKE warning light on the dashboard. You can measure runout when installing brand new brake rotors or wheel bearing hubs to make sure you are getting quality parts. Cheap aftermarket parts aren’t always built well to meet the factory specifications.
Can you fix excessive runout after turning rotors?
Turning rotors doesn’t always fix the problem of excessive runout. In my case, after turning the rotor runout decreased from 0.004 to 0.002 inch. If excessive runout still can’t be fixed after turning the rotor, it will need to be replaced. After you are finished, re-install everything in the reverse order of removal.
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.
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.
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.
Conclusion
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.
How to clean a piston caliper?
Split the caliper, wrap the half caliper it in a large rag and use an air line to puff the piston out, wipe clean all surfaces with only a clean rag, use a brass o-ring pick to gently remove the piston seal and wipe it down, carefully inspect seal condition (replace as necessary), smear some Red-Grease (auto parts supply) on the rubber seal and carefully install.
Does a bent rotor cause dragging?
Doesn't sound bent to me. A bent rotor does not cause dragging. When a rotor is bent it will cause a gap to form between the pads and the rotor and you have to pump the brakes to get them to grab.
