brake problem

[hinggu]

Hey guys. A few weeks back, I crashed my car into a f-ing curb and screwed up the control arm, hub assembley and so forth. I got this fixed at the dealership. When I got the car back, I noticed a "whoop whoop whoop" sound coming from the front brake (the one I had repaired) when I brake. I took it back to the dealership and they said it was a glazing problem that is "very common among sentras." They remachined the rotor under warranty and then it got better for a while. Now, especially when the car is cold, the "whoop" sound is back. Is the rotor warped maybe?? Or is there a problem with the caliper? I don't think the dealer is correct about the glazing problem or are they? Any help would be great!!!

[romabimmer]

Have them measure the offset of the caliper, if it's mounted too far inboard or outboard it will cause 1 pad to rub the rotor all the time. Eventually the pad material builds up on the rotor and this gives you that "warped" feeling, your rotor is not warped.

Also if the caliper is mounted askew you will have problems, angled too muchn from nominal.

If it is mounted improperly then you need to figure out why, can be multiple reasons.

[romabimmer]

Now this can be a simple issue of pad material on the rotor due to improper break in procedure.

New pad and rotors need a good breakin procedure to work well:

While the vehicle is stationary, pump brakes to ensure a firm pedal.

Drive the vehicle cautiously to test fit and function.

The brakes should be smooth, with no vibrations, judder, etc.

Drive the vehicle to a remote area and perform at least 30 brake applications of 3-second duration. Use light/medium deceleration with varying starting speeds. Leave at least 10 seconds between each brake application.
The purpose of this procedure is to gradually increase the temperature in the components without inducing thermal shock, and to mate the brake pad and disc friction surfaces.

After the repeated stops, drive the vehicle for a few miles with little or no braking in order to adequately cool the components.

After the above process is completed, the system is ready for normal use.

When the system achieves elevated brake temperatures for the first time, a slight increase in pedal travel and pedal effort may occur. After this first "fade" and proper cooling, the system will maintain its optimum performance at all temperatures.