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Discussion Starter · #1 ·
I've been looking for brake pads and rotors for a friend, and I see O.E. rotors, and the supposedly "upgrade" ones that have drilled holes and/or slots for only a few bucks more. Are the drilled or slotted rotors really any better?
 

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Discussion Starter · #18 ·
Mine are warped, no doubt about it.
How would you know? The only effect of warped rotors would be that the caliper slides back and forth on the slide pins alot, but it doesn't affect how the brakes respond. If you're assuming they're warped because the brake pedal goes up and down when you press on the brakes, that's not because the rotors are warped; it's because they have pad material fused to them, making them thicker in some areas than others. If you want to assumed they are warped, go right ahead. Rotors that are actually warped cannot be turned (machined), but those affected by having pad material on them could be. However, for either problem, the easiest, and often the most economical solution is to replace the rotors, anyway.
 

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Discussion Starter · #20 ·
Warped Brake Rotors—The Facts

The fact is: The discs were never warped at all. Every warped brake disc that we’ve investigated with the assistance of our suppliers shows uneven patches of friction material from the brake pads on the surface of the disc. These patches cause variation in thickness (run-out) and the vibration under braking. Brake manufacturers have been struggling to deal with this situation for years because warped discs are so readily blamed for brake-related vibrations.
 

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Discussion Starter · #28 ·
While that may be true in some instances, I have seen plenty of rotors that are actually warped as a professional automotive tech. In the Honda world the 09-15 pilots and 12-17 odysseys constantly have rotors warping. The exact reason I am unsure, but I speculate it had something to do with the front and rear brakes being undersized for the vehicles. Front's being undersized allowing for a greater build up of heat in the rotors and rears being undersized causing the fronts to work harder. For the odysseys Honda even updated the rotor design for improved cooling.
I don't doubt that both conditions may happen, but as I said, the preferred solution is the same regardless - replacement of the rotors.

There's some good info on bedding the brakes in the article, though, to minimize the occurrence of the build-up problem.
 

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Discussion Starter · #34 ·
Rotors do warp... I have resurfaced hundreds of rotors because of warping as a mechanic.
Not trying to start a fight. You're sure that these hundreds are rotors were actually the same thickness face to face at all locations, but 'shifted' forward and back as they went around? They weren't actually thicker in some areas than others?
 

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Discussion Starter · #39 ·
All I know is that they were in fact warped and resurfacing them cured their shaky steering wheels while braking afterwards.
So you're saying you never measured the thickness of the rotors, you just machined them until the faces were flat? If that's the case, you don't really know if they were warped or just thicker in some areas.
I've been repairing and maintaining cars and trucks for over 45 years now.
Good for you. Many others could claim the same. That doesn't prove that you're right. Since machining the rotors works for either problem, the fact that maching the rotors resolved the issue is not evidence that your assumption of the cause is correct.
 

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Discussion Starter · #48 ·
Has enough people in here convince you to rotors warping?
I never said rotors never get warped (See post #28). Neither did the article I linked to. I just called into question your assertion that all of the rotors you've machined over the years were all warped, as opposed to being thicker from deposited pad material. From what I've read, both conditions do occur. Only by putting a caliper on the rotor at multiple locations and comparing the measurements would you be able to tell which condition the rotors suffer from. The solution is the same, but the causes are different, and the issue with deposited pad material is preventable with proper break-in of new rotors and pads.
 

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Discussion Starter · #50 ·
Ive never seen brake pad material (fuse) to rotors or drums. Thats on motorcycles to tractor trailers and everything in between.
I have, although it's not as obvious to the eye as you might think, especially with metallic pads. Pulsing brakes are a classic sign of this condition. Mine originated with an emergency braking situation and actually got worse over the next months.
 

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Discussion Starter · #52 ·
Brakes pulsate, I buy new rotors. I don’t care whether it is brake pad deposits or warpage.
Me too. As I said, I posted the article about the brake pad deposits so people would be aware that proper bedding/break-in can prevent this problem. Also, many times warped rotors cannot be turned, because they would be too thin if you did, but ones with deposits could be. Granted, I can't find a machine shop around here that even turns rotors as a regular thing, so the prices to have it done are more than new rotors. There's also far less hassle and downtime to replace them.

I replace the rotors whenever the pads need replaced. Supposedly, you can change rotors every other time the pads are changed...if they're not too worn down/thin, warped, have pad deposits on them, and if they don't have grooves, and if half a dozen other things that I don't care to check are true...not worth the hassle to inspect them that closely, when it takes 5 minutes longer to replace the rotors while I have the calipers off, anyway. Of course, since I plan on that from the beginning, I don't replace the pads until the pad material is completely gone. I trim, remove, or bend the little warning tabs, so I don't have to worry about them squeaking until I hit the metal of the backing.
 

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Discussion Starter · #68 ·
So if you want more to argue about discuss the difference, benefits, issues between metallic and what we'll call Nao type pads, those being the run of the mill pads that 99.9% of cars use.
I'd be interested in hearing from someone knowledgeable on the subject, which you seem to be. I've read alot that says ceramic are the best, but that comes from places that are trying to sell them, so I don't know if that's really true.
 

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Discussion Starter · #70 ·
Those are some interesting pictures, LawrenceS. It does support the transfer of pad material to the rotors.

I'm still trying to figure out how warped rotors supposedly cause the brake pedal to pulse. Warped rotors would still be the same thickness everywhere. The entire caliper would potentially move, sliding on the pins, but the piston wouldn't move.
 
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