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Old 09-16-2002, 12:54 AM   #1
mpower1226
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rotors bent, help

I guess my rotors are bent. Can you verify sympton?

When ever I applie brake from highway or high speed,
I feel vibration through the steering wheel.

However I do not feel any vibration while my foot is on the gas pedal.

If so, How much do you think it will cost to mechine the rotor until I save money to change it.
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Old 09-16-2002, 01:01 AM   #2
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you should see how bad mine are!!! the brakes still work good, but the damn wheel shakes like a mother ****er, worst is coming down from 80-100 km/h.... deyammm oh well
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Old 09-16-2002, 01:07 AM   #3
mpower1226
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yeah, I know... I just feel very insecure when I applie brake..
Its really bad. My whole steering wheel start shakes..
Rolled out, Did you just leave it like that? or have you fixed it.
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Old 09-16-2002, 01:08 AM   #4
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advice

I know many of you will already know this. But in any case, I thought I'd post it.

NEVER. NEVER wash your car right after you've driven it for an extended period!. Give it at least 20min I'd say to cool down. Especially your rotors!!! I've seen people at the spray booths hose their HOT rotors down and watched heaps of steam come out of them. This can cause rotors to warp. I think the science behind it is pretty simple so I won't explain.

Anyhow. Since you were talking about warped rotors, I thought it was a good thing to mention.

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Old 09-16-2002, 01:13 AM   #5
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i left it like that... frankly i dont give a ****... it doesn't affect my stopping, its only one rotor, my front right... it looks/feels weird, but whatever.... im selling the thing anyways... bah
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Old 09-16-2002, 01:21 AM   #6
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Rolled out, Dont tell me your are selling that M3 in your sig,
. Thats one awsome car.
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Old 09-17-2002, 03:25 PM   #7
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Also when you drive on the highway you might feel the car wobble or it might pull to one side. Think of the wheel as a rotating mass. If a rotor is warped its almost like the wheel isn't balanced. Don't worry, cheap solution is to get it resurfaced. It weakens the rotor but its a very cheap quick solution. Plus talk to Gino at Elite auto, he gets Brembo rotors for like $80 each. When I bought my car the rotor was already slightly warped.. when I brake at 120km/h the steering wheel wobbles like a bitch. When I hit 140km/h+ the car shakes a lot. I don't like it, I'm going to get my rotors replaced. It does affect stopping power. My personal opinion. BMW rotors are crap! If you heel and toe a lot the rotors will most certainly warp.

Rico is right, don't get any water into the rotor while its hot. My friend made the mistake of doing that after I drove the car very hard. He sprayed water into the wheels and said to me. Hey Bryan, look at all the smoke comming out of your wheels, it looks like you doing a burnout. Holy crap after that day the rotor was warped.

Bryan
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Old 09-18-2002, 09:37 AM   #8
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Why is is that when the topic of brakes comes up, the BS starts flowing?

Warping rototrs by getting them wet? C'mon now. Did it ever occur to you guys that your rotors are EXPOSED to the elements as you drive down the road?
Show me the part in your owners' manual where it says not to get your rotors wet when they're hot?
Do you think a company with engineers like BMW's would design rotors that would warp if you go them wet? NO. NO. NO.

Also, heel & toe downshifting has zero to do with warped rotors.
It is a technique for matching revs as you brake and downshift. It has nothing to do with how hard you brake, how hot you get your rotors, or how long they will stay true.

This kind of BS belongs in the same file as the "Cross Drilled Rotors Provide Better Braking" nonsense.

GT?
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Old 09-20-2002, 02:11 AM   #9
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BS?

Got Torque,

It's actually simple physics. You try taking a very, very hot metal plate, and then spraying cold water (from a hose for example) on it. Actually, try this------drive YOUR car, use the brakes hard. Hard enough to get it's temperature waaaay up there, and then spray it with a hose as soon as you park it! Talk to me after that my friend! Let us all know, who's BS'ing! I personally know people it's happened to!

Rico

P.S. rain water is usually warmer than water coming out of the hose in your garage!
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Old 09-20-2002, 09:37 AM   #10
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I know what you're saying- and I'm saying that warpage under those circumstances is likely due to something other than the water. A cast iron rotor is not nearly thin enough to be distorted by some superficial surface water. We're talking cast iron an inch thick, not an aluminum frypan.

What would happen if you drove your car hard in the springtime, got the brakes hot as hell, then drove through a puddle of melting snow/ice? Do your rotors warp? NO.

If you're so sure that you're right, you better get on the phone to all of the automakers fast to tell them that they better start protecting their rotors from all that water out there.....

It's not as simple as you make it out to be. There are many things that can give a driver the sensation of a "warped rotor". In many cases the feeling and vibration is an uneven transfer of pad material due to overheating, not an actual warping of the iron itself.

GT?
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Last edited by got torque?; 09-20-2002 at 09:41 AM.
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Old 09-20-2002, 04:10 PM   #11
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warping

I work at a car rental place and when ever we spray water on the cars after we drive (really hard) the rotors warp. This is caused by the extreme temp change in the rotor, not by the water.

I love killing company cars. hehe
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Old 09-20-2002, 09:25 PM   #12
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Quote:
Originally posted by got torque?
Why is is that when the topic of brakes comes up, the BS starts flowing?

Warping rototrs by getting them wet? C'mon now. Did it ever occur to you guys that your rotors are EXPOSED to the elements as you drive down the road?
Show me the part in your owners' manual where it says not to get your rotors wet when they're hot?
Do you think a company with engineers like BMW's would design rotors that would warp if you go them wet? NO. NO. NO.

Also, heel & toe downshifting has zero to do with warped rotors.
It is a technique for matching revs as you brake and downshift. It has nothing to do with how hard you brake, how hot you get your rotors, or how long they will stay true.

This kind of BS belongs in the same file as the "Cross Drilled Rotors Provide Better Braking" nonsense.

GT?
When you heel and toe, your braking and applying the throttle at the same time. It puts more stress on the rotors. Do you know what the term "driving old granny style" means? Its when people start the car from stop and step on the brake while also stepping on the throttle at the same time. I have no idea why old people do this, but it warps rotors. It has happened to so many people I know. I know heel and toeing isn't as extreme but it does wear off rotors and increase the chance of warping more. I use heel and toe in the corners and I'm sure it heats up the rotors pretty bad at high speeds.

Lastly, when it rains your not directly spraying water into your rotors correct? When your rotors are really hot, I mean from racing at the track, if it rains and you brake hard or get lots of water into your rotors, there is a good chance it may warp. Just because it doesn't happen often doesn't mean it never happens.

Bryan
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Last edited by Autotechnica; 09-20-2002 at 09:27 PM.
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Old 09-20-2002, 10:29 PM   #13
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Bryan,

I have a feeling that you use "heel and toe" tecnique incorrectly. Heel and toe does NOT put more stress on the rotors. When you heel and toe you NEVER apply brakes and gas at the same time with the clutch engaged. The gas pedal is ONLY applied to bump up the RPMs for downshifting.

read this article, it will help you to clear some things up:

http://www.happytogether.com/318ti/n...ing/index.html

Heel and toe does not wear rotors and pads more than normal braking, it actually improves the pad wear a bit since you use the engine's momentum to slow the car down.

Serge


Quote:
Originally posted by MTRD


When you heel and toe, your braking and applying the throttle at the same time. It puts more stress on the rotors. Do you know what the term "driving old granny style" means? Its when people start the car from stop and step on the brake while also stepping on the throttle at the same time. I have no idea why old people do this, but it warps rotors. It has happened to so many people I know. I know heel and toeing isn't as extreme but it does wear off rotors and increase the chance of warping more. I use heel and toe in the corners and I'm sure it heats up the rotors pretty bad at high speeds.

Lastly, when it rains your not directly spraying water into your rotors correct? When your rotors are really hot, I mean from racing at the track, if it rains and you brake hard or get lots of water into your rotors, there is a good chance it may warp. Just because it doesn't happen often doesn't mean it never happens.

Bryan
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Old 09-20-2002, 10:32 PM   #14
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Quote:
Originally posted by MTRD


When you heel and toe, your braking and applying the throttle at the same time. It puts more stress on the rotors. Do you know what the term "driving old granny style" means? Its when people start the car from stop and step on the brake while also stepping on the throttle at the same time. I have no idea why old people do this, but it warps rotors. It has happened to so many people I know. I know heel and toeing isn't as extreme but it does wear off rotors and increase the chance of warping more. I use heel and toe in the corners and I'm sure it heats up the rotors pretty bad at high speeds.

Lastly, when it rains your not directly spraying water into your rotors correct? When your rotors are really hot, I mean from racing at the track, if it rains and you brake hard or get lots of water into your rotors, there is a good chance it may warp. Just because it doesn't happen often doesn't mean it never happens.

Bryan
Well Bryan, I hate to do this to you, but you're absolutely wrong on this one....

1) When you heel / toe, you're squeezing the brake pedal, blipping the throttle, and have the clutch in the majority of the time, as you downshift. You're not attempting to accelerate AND brake at the same time.

2) Accelerating / braking simultaneously has NOTHING to do with warping rotors.... At that point, you're not actually allowing the rotors to cool, which isn't an issue in the warping of rotors. All the *grannies* are actually doing is merely burning off more brake pad than they really need to....nothing more harmful than that.

Rotors *can* potentially warp when subjected to a massive temperature change, but even spraying cold water from a car wash onto them shouldn't warp them. What you're likely feeling is the now abnormal spread of brake pad material on the rotors, causing it to feel *warped*. Spots where high pressure water was directed at the rotors get cleaned, while other spots aren't.

Simply put, the VAST majority of warped rotors have more to do with brake pad material, than with variation in temperature. What you actually feel as a *warp* is in fact a rotor which has an uneven deposit of pad material on it...

As to getting rain onto the rotors, even when driving on the track, once again, not likely to warp rotors. As I said above, you're more likely feeling a disparity in pad material on the rotor surface, which *feels* like a warped rotor.

If we'd like to get into the physics of how this works, we can probably start another thread which discusses this. It covers such things as how your brakes actually work, what factors really apply, and what things like *bedding in* really are doing.


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Old 09-20-2002, 11:47 PM   #15
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