530inOK

+2...My aftermarket drilled and slotted rotors make the same noise. The circular grooves will wear away eventually. My rotors with about the same mileage look very similar.
+1

BlueHorse

It is just strange that these X marks only appear in front rotors, and none in rear rotors. Both front and rear rotors were bought in the same package, same brand and model.

Do you remember how many miles it took your X marks to fade away?

Thanks!

balbs

To be honest, I never checked how long it took for the X to go away. All I know was it was there when the rotors were new and now it has the tell tale sign of normal pad to rotor wear.

BlueHorse

I am going to do the test of marking black lines on all 4 rotors this weekend, and observe whether they get cleaned out unevenly between front and back. I did a quick test the other night, and was surprised to see they required many brakings to wear out. Both front and rear lines wore out. Will need to test more to see if there is a difference in how soon they wear out.

My problem seems to be more force between rear rotors/pads than front rotors/pads. I thought about how the entire system works (brake booster, vaccum, proportioning valve, calipers, pads and rotors). Given I have no fluid leak, and both front and back caliper pistons appear to be free moving, there are only two possible reasons I can think of:

1. Does the braking system in this car have a proportioning valve? Somehow the proportioning valve is directing more pressure to the rear?

2. If there are air bubbles in certain locations of the front side, AND if somehow those air bubbles only impacts the front side braking power but not the rear side. Is this possible given the design of the system?

BlueHorse

Hello, it has been almost two years. The "X" marks on the front rotors are now 80% gone. So my theory is that the front and rear rotors, despite same brand and bought in one package, were made differently. Case closed.