Vibration While Braking? (How I diagnose warped rotors)

In my estimation warped up brake rotors are usually the cause of a vibration while braking. It is very common and I deal with it as a technician regularly. In this video I I first explain how I diagnose warped up brake rotors using "guesstamation". Do note that the first method shown does use a little guess work but is usually pretty accurate when it comes to diagnosing a vibration caused by warped rotors. The second method I show is more accurate and is the "text book" way to confirm a warped rotor.Show more

Once it is determined that the vehicle has a vibration while braking it will then be necessary to figure out weather the vibration is caused by warped front rotors or warped rear rotors. I do this by paying attention to the steering wheel while braking. Usually when the front rotors are warped up it will cause a wobble in the steering wheel while the brakes are applied. Usually when the rear rotors are warped up it will caused a vibration in the seat while the brakes are applied. Once I determine weather the front or the rear rotors are suspect I will then measure the thickness of the rotors to determine if they are able to be turned or not. Once they are measured and it is determined that they are thick enough I will then turn the rotors. Typically it will be very noticeable that a rotor is warped when they are being turned as you can see the wobble of the rotor against the bit of the brake lathe. Once the rotors have been turned I will then measure them again to be sure they are still within specifications. This is my way of addressing warped rotors.

A more accurate way to diagnose warped brake rotors would be to used a dial indicator. Of coarse you will still want to get an idea of which end of the vehicle the vibration is coming from by paying attention to where you feel the vibration as explained before. Once you determine which end of the vehicle the vibration is coming from you would then want to measure the warpage of the rotors that you suspect are warped. If you find the rotors are warped it would then be advised to turn them. (Always measure the thickness of the rotors before and after refinishing them to confirm that they are within specifications.) Note: you can find a specification for warpage or run out in a repair manual. )

As mentioned in the video, a faulty component other than the rotor can cause a false reading when measuring warpage. If you are suspicious that the warpage reading is caused by another component then it would be advised to measure rotor warpage while the rotor is mounted to a brake lathe. This will give you a true warpage measurement of the rotors in suspect.

Note: It is my recommendation that when turning rotors they should always be turned in pairs. i.e. front right and front left or rear right and rear left. It is also my recommendation that the pads be replaced on whichever rotors are turned. This in my opinion reduces the risk of brake squeak and helps the vehicle to have equal and even braking force.

Note: Do not turn rotors passed the specification for thickness outlined in you repair manual.

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Repair your vehicle at your own risk! Barbour's auto help does not guaranty a proper diagnosis or repair using these techniques.