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Symptoms of a warped rotor


Mel87

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What exactly are the symptoms, or how can I tell if my rotor is warped? I had just changed the front brake pads on my car, and when driving slow I can hear a slight oscillating scrape noise coming from the front left wheel, resulting faster when I drive faster. When I lightly apply the brakes I can hear it a little more. Would this be result of a slightly warped rotor? I can also feel slight bouncing in the brake pedal when applying.

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When you apply the bake if you feel a pulsation in th pedal that could mean it is a warped rotor. Sometimes you can hear them like you described. Are you sure it's not a wheel bearing sound?

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I don't think it is a wheel bearing, although I have never driven a car with a bad bearing so I don't really know what it sounds like. But there is the pulsation in the brake pedal.

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Hmm, well the only screach noise I hear is oscillating, it isn't continuous. The pulse in the brake pedal is what lead me to think it would be the rotor. How often do wheel bearings go bad?

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You could get them turned.

 

Would that solve the issue?

 

From what I was told by my dad, stock rotors are the best. He claims aftermarket rotors will warp more easy and are never right. Now he is like 50, so maybe back in the day they weren't as good as stock ones... Is that true?

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Yeah it is only when applying the brakes. I'll be damned if I have to get new rotors.

 

New rotors really aren't that expensive...

 

Turning them makes an already undersized and cheaply made rotor even thinner and even more susceptible to warpage. You turn them and they will warp again in short order.

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If they are warped they can be turned if they aren't too badly warped. That would put them back in line.

 

I have an uncle that destined and manufactured disk brakes back in the 60s. Well, long story short he said the basic design hasn't changed much.

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Alright, I will keep that as an option. I may try to turn them for now, if it continues I will investigate better rotors. I wonder if slamming on the brake the other week cause of an asshole that pulled out in front of me would cause it...:shrug:

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New rotors are like 40 something dollars. Slotted ones are more than that.

 

When I bought them for the GTP they were like 20-25 for the fronts, and maybe $30 for the rears :dunno:

 

EDIT: I'm talking each, so if you were talking a pair then we're on the same page :thumbsup:

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When I was searching for rotors this past summer I realized that they're all the same. They even come in the same packaging. So personally I'd get the cheapest ones. Stock rotors aren't always good either. The ones on the HHR are shit...

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Alright, I will keep that as an option. I may try to turn them for now, if it continues I will investigate better rotors. I wonder if slamming on the brake the other week cause of an asshole that pulled out in front of me would cause it...:shrug:

 

Its possible. The front rotors on my Grand Prix are a little warped at the moment, I imagine it is because I'm a young/aggressive driver. I also have no idea when they were replaced, I have not done so in the time I've owned the car (over 2 years). I've done pads on the front and pads & rotors on the rear twice, but no rotors on the front. I really notice the warpage coming down a long hill or off the highway off ramp.

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W-bodies from the factory have composite rotors because they are lighter. If they are turned, there is a special piece that HAS to be used when they are turned on the lathe or they will warp. The piece bolts down with lugnuts on the thin stamped steel hub of the rotor as if the actual was wheel bolted to it so it distorts in the same manner as it will when it's on the car. It will distort differently if not used, and the rotor will warp. GM sent this special tool to all dealers, so they should have it. Maybe I'm wrong, but I'm guessing there aren't many independents or autoparts stores than can turn one correctly. If the rotors are warped and can be turned again, inquire if a dealer can turn composite rotors and have them do it, or you can get new rotors, most of which are regular cast iron replacements, although ACDelco rotors are still available in factory composite. I just ordered some for my sister's Z34. I would not just drop the rotors off at your local street corner hack shop or autoparts store to be turned or you will likely be back where you are. That's what my dad did on my sister's car and its now why I'm replacing the rotors (to thin now for me to turn correctly).

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Brake pedal pulsing is usually due to warped rotors/out-of-round drums. Often accompanied with steering wheel shake if the front rotors are bad--but not always.

 

Steering wheel shake without pedal pulse when braking can be broken belt in a front tire. I had recent experience with that.

 

To verify front vs. rear, stop with the emergency brake. (Don't lock the wheels) If the car stops smoothly with the emergency brake, the problem is surely in the front. If the car shudders to a stop with the emergency brake, the problem is surely in the rear.

 

Turning rotors is a well-established repair procedure--but--as has been said, it shouldn't be done by a moron.

 

Cheap rotors are practically guaranteed to be Communist Junk. Expensive rotors are almost guaranteed to be Communist Junk. There's a TREMENDOUS amount of Chinese crap infecting the brake rotor business; including "Ultra Premium" (HA!) parts from well-known name brands.

 

Drilling 'n' slotting (by itself) doesn't do squat except look fancy. If they've drilled and/or slotted a QUALITY rotor, the quality rotor might be worth paying extra for. A drilled/slotted cheap-junk Chinese rotor is no better than a plain cheap-junk Chinese rotor.

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Bad belt in the tire usually doesn't make noise.

 

Turning rotors that are as worthless as the ones on our cars is NOT economical.

 

Aside from being annoying IF it is just the rotors your car is still safe to drive that way.

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