J'sWorld

I know rotors warp. I also know that if you are doing 100 mph stoppies on a sportbike you are going to find out real quick how bad they are warped and what blood, calcium, plastic, and asphalt taste like mixed together. Warped rotors really mess up your balance point on your front tire and make for a nice slapper.

Matt O.

Sorry, we gotta define "warped" and "rotors." The hub portion is not the rotor, and an ill seated rotor on the mounting point is not what I would call warped rotor, nor did it come from stomping on the brakes. There's warped, and there's "warped."

J'sWorld

I agree it would be hard to say if a rotor's centerline is warped on a typical cast and vented rotor. Still, the op had experienced a problem that was trued on lathe. We will probably never know the original cause without the rotor being bolted to a proven true lathe and checked right out of the box.

mtnrat

Happy with my guys. They torque stick to a certain point and use regularly calibrated torque wrenches going through two cycles to get to proper spec. The owner is **** where it count and his guys are too. I do most of my work, but when I don't I can drop in at any time and watch, look, ask questions, make comments and be a general pain in the ***. When they are busy and cannot help when i need a specialty tool, he lets me use the press, gear pullers etc. Only problem: no PIWIS.

8202632

Replaced all pads and rotors over the last couple of days. Car drives perfect. Did nothing special.

TomF

^This^ +1

Cheers,
TomF

Petza914

The pad contact area of a rotor absolutely can warp and cause steering wheel vibration under braking - usually the lighter the brake pedal pressure, the worse the vibration. Anyone who says rotors don't actually warp has never owned a really heavy SUV with undersized rotors from the factory. Our first year Infiniti QX56 would warp a set of front rotors anywhere from 5,000-15,000 miles. Infiniti finally admitted to the issue and tried inexpensive rectification which was to change the pads to a softer, dustier compound so that you got more braking effect with less force of the pads onto the rotor. During that service, they also turned the rotors to make them true again, but this combination did not resolve the issue - turning the rotors actually removed some of the metal that acts as the heat sink and helps prevent the warping. After the third set of warranty replacement rotors and being tired of the brakes getting worse as we got to the replacement threshold, and having to take the car to the dealer, which is an hour away, I bit the bullet and replaced the rotors myself with cryo versions that were also cross-drilled. The cross-drilling, though it also removes metal (reduces the heat sink) also increases the airflow and exposed surface area of metal to air so the rotors can cool faster once they become hot. At the same time, I changed to Hawk LTS pads. The last set of OEM replacement rotors came off at 40,000 miles and I sold the vehicle with the brake setup I installed at 180,000 miles without any further brake issues.

You could tell the rotors were actually warped by removing the wheel and setting up pin on a stand, spinning the rotor by hand you could see it contacting and then moving away from the pin as it rotated - to me - that's clearly bent metal and the rotor had never been removed from the hub between when it was brand new and running true to when it was warped and no longer running true.

TomF

...how do you know it is not pad material deposited (basically fused) to the rotor because of overheating...

Cheers,
TomF

Petza914

Pad material doesn't build up high enough where when looking down the face of the rotor, you can actually see it moving in and out - that happens at a more microscopic level where it grabs and releases which makes you feel like it might be warped, but isn't really visually noticeable when measuring runout.

19psi

I'm also guessing most of these experts never had to buy and maintain a cheap used car, even as a teenager.
They never had to experience a caliper that didn't fully retract. Feeling the drag, pulling over and then seeing smoke billowing out from a wheel well. Noticing the glowing, cherry red hot rotor...which is easily viewable because your plastic hubcap melted and fell off a few blocks back.

In the end, you're left with a rotor that looks just like the Led Zeppelin LP you accidentally left in your car on that sunny July day.

AGARubberDuck

PSA. The runout you see in the following video is not a warped rotor. Do not trust your senses.. this is the twilight zone.

Petza914

For that to be a valid test, he would need to put the lug nuts back on to be sure the rotor is evenly clamped against the hub. If it still does that to the gauge, then it is most likely a warped rotor.

AGARubberDuck

Yeah, you have a point there. I suspect the wheel came off and the rotor is still seized in place, as that's always the case for me on old rotors. However, that doesn't make for a very definitive test.

J'sWorld

Ahhh, Rennlist.....

The only forum where there are more replies, arguments, and questions on warped or not rotors than a never been done before built big turbo Cayenne.

AGARubberDuck

To be fair, everyone deals with brakes at some point in ownership. Kudos to you for what you're doing, but that's making the best of a worst-case scenario very few people will deal with. I sincerely hope to never be in the spot you were in that nudged you down that path.

As far as brakes, who cares what you call the problem. Turning or replacing fixes it.