How do you tell if brake rotors need replacing??

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avp12304

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I'v got an 05 ram and my brakes need some attention, how do you tell if the brake rotors need replacing? is there any obvious signs? I checked my brake fluid its good, changed the pads, on the front..about to do the back, but am curious as to how you tell exactly when its time to replace the rotors?? thanks
 

MADDOG

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Two ways...

1. Thickness. Minimum thickness is usually stamped on the rotor, on the rear side of the rotor hat. If you have to machine a rotor and it will reduce the thickness to a measurement under the minimum thickness, toss 'em.

2. Run out. If the rotor exhibits too much runout (wobble or bending) then toss it out.
 

lharrell79

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First, the rotors should have a smooth surface. If the rotors have grooves, they will need to be turned down until they are smooth. Once the rotors are smooth, you will need to measure the rotor thickness and rotor runout.

The following specs are from the 2004 FSM:

Rotors.png
 

Jerseystyle

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Check for uneven pad wear as well. If the rotors are warped you'd probably get some vibration in the pedal when breaking.

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JPT

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My honest opinion (it isn't really required, but my personal preference), Do the job yourself, and with the added savings, change the rotors every time. They really aren't that more expensive, and you dont have to go sports performance if you aren't racing or towing near capacity.

EDIT: My reason is, I've had too many problems with warped rotors, it doesn't help the thinner the rotor (from cutting). If you aren't replacing the rotors you should at least have them cut at a machine shop/mechanic so that the new pads properly match with the rotors.
 
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Jerseystyle

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Agreed. Brakes are super easy to replace (especially discs) and shops charge a ton.

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