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Old 09-20-2002, 11:22 PM   #16
Autotechnica
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Quote:
Originally posted by KIRASIR
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


I know that already. Heel and toe down shifting is different than cornering using heel and toe. When cornering using heel and toe you do apply the brakes and blip the throttle to acceleration through the corner yet keeping it under control with the brakes. While downshifting heel and toe there is no brakes and throttle applied at the same time. Don't worry, I know what I'm doing.

Bryan
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Old 09-20-2002, 11:37 PM   #17
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Quote:
Originally posted by Bad-Karma


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.


Pat
Thanks Pat,

I was actually waiting for you to come on here and clear things up All the things I thought were true I heard from other people and is based on no theory at all. I just thought its like having a very hot sheet of metal, then pouring cold water on it. Won't the sheet of metal warp?

Thanks,

Bryan
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Old 09-20-2002, 11:45 PM   #18
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What you are describing is the easiest way to end up in a ditch.

Serge

Quote:
Originally posted by MTRD
When cornering using heel and toe you do apply the brakes and blip the throttle to acceleration through the corner yet keeping it under control with the brakes. While downshifting heel and toe there is no brakes and throttle applied at the same time. Don't worry, I know what I'm doing.

Bryan [/b]
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Old 09-20-2002, 11:55 PM   #19
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Quote:
Originally posted by KIRASIR
What you are describing is the easiest way to end up in a ditch.

Serge

How is that? The easiest way to end up in a ditch is to throw your car into the corner, then mash on the brakes. Thats not what I was describing.

Bryan
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Old 09-21-2002, 10:53 AM   #20
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Pat

I'm ending my comments right now.

Like Gamite said. The Pat has spoken. Thank you......

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Old 07-04-2013, 12:37 AM   #21
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Hi,

This is a very old thread but I had a lot of headache with warped brakes so I have some questions for you guys.

2-3 months after I bought my 323ci, my steering wheel started to shake under braking at high speeds. Therefore, I got the rotors resurfaced. Problem was solved for another 2-3 months and it came back. This time, I replaced the rotors and also pads. Again, couple months later, vibration started to come back. I thought one of my calipers had a problem, which causes one pad to always touch the rotor, therefore heat only one side of rotor while other side is cool, which warps it. So I replaced both calipers and rotors, kept the same pads. Problem went away for couple of months again. I recently drove from Toronto to New York, and the problem started again. It looks like when I drive long periods of time on highway, the problem comes back. After spending so much time and effort on this, I do not know what causes the warping and how I can fix it. Does anyone here have any idea what my problem might be? I use Zimmerman coated rotors btw.

Thanks a lot,
Sergio
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Old 07-04-2013, 08:22 AM   #22
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Sounds like your control arm bushings and/or ball joints are shot, replacing the brake parts was probably just masking the real problem.
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Old 07-04-2013, 11:14 AM   #23
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As far as I know they are fine, but I will have a look at them asap, thanks for the comment.
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Old 07-04-2013, 01:42 PM   #24
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If it was a bad balljoint or something, resurfacing the rotors wouldn't help. I bet one of your calipers is either seized or on its last legs, causing it to drag, overheat the rotor/pad and deposit unevenly.

EDIT: nevermind, missed the part that you replaced both calipers...

EDIT2: just throwing things out there... do you still have winter tires on? Some lower speed rated tires like winters, will overheat and bulge much past 100.

In the end it might just be your driving style.
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Old 07-04-2013, 01:50 PM   #25
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this is almost always a sh*tty pad problem.

rotors dont warp. any run out is from poor pad deposits.
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Old 07-04-2013, 02:42 PM   #26
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New rotors can warp, BMW recommends a break in (bedding) in period.
Proper installation and cleaning before install will prevent premature/uneven wear as well.

Get new rotors and let them bed in.

If you have a temperature gun, check the temps at each wheel for excessive heat.
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Old 07-04-2013, 04:04 PM   #27
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Quote:
Originally Posted by sergiomordo View Post
As far as I know they are fine, but I will have a look at them asap, thanks for the comment.
This is your problem

aftermarket are known to warp after some period of driving. Buy bmw oem rotors. I have the same problem and needed to resurface my set. secondly. If the calipers and sliders are not serviced properly you may get pad drag or binding which will heat up the rotor and eventually cause warping. the sliders and carriers should be serviced thoroughly.

This is why bmw swears by their product. That isn't to say bmw rotors have not been returned due to warping. it's happened to me once (warranty return) but only in rare cases.

Best to go oem.

CAB's will cause vibration whether brakes are applied or not.
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Old 07-04-2013, 04:38 PM   #28
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Old 07-05-2013, 11:53 AM   #29
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1st off BMW pads and rotors are designed to wear out Simultaneously. This is suppose to provide better braking/shorter stopping by causing more friction between both surfaces. This is why BMW recommends you replace both pad and rotor at the same time. And this is why your cars front wheels get covered in brake dust alot faster then other cars. Plus the pad material probably does not help dust either. This is why you shouldn't mechine your rotors. If they need to be mechined, then chances are you have already worn them thin and there is not enough rotor left to properly mechine them. That being said. The number one reason for warped rotors is...
heating up your rotors and immediately parking your car. Whats happening is that the rotors are cooling down evenly except where the pad makes contact with the rotor. This keeps that one spot hot while the rest of the rotor cools down. It's not how fast the rotors cool down but how evenly they cool down. It is the uneven cool down that is the biggest blame in warped rotors. Not to mention the thinning of the rotor makes this problem even worse. This can still happen when the rotors are not worn thin but not as easily. Of course this can still happen to aftermarket rotors as well. No rotor is safe from this but some rotors of better quality should be better resistant to warping.

I have oem brakes on my car and my rotors are worn real thin. I can see the original thickness of the rotor on the part of the rotor where the pad does not make contact with the rotor. So I know that they are worn thin. I have changed pads 3 times to the one set of rotors. First time with a new set of pads and then I was given use pads with life on them for the 2nd and 3rd time. I have not had any warping issue with my rotors because after hard braking I would drive my car slowly around the block not using much if any brake and letting the rotors cool alittle. Once around the block is enough as you don't have to cool the rotors completly but make sure that they are not race track hot when you park. You can park your car with the rotors hot from normal driving and be fine. Before I knew this I warped my old rotors from parking hot. And my old rotors were even thicker then the rotors I have now because of less wear. Both oem rotors but the current ones worn thin don't gat parked hot and are still true. My driving style has not changed between both sets of rotors as the driving conditions have not changed either. I heel toe all the time. I wash my wheels and spray my rotors when they are hot. Not race track hot, but hot from normal driving and yes they do steam. I immediately get in my car and start driving once the wheels are clean and the rotors are once again the same temp evenly. Remember, it is not necessarily how fast they cool down but how evenly they cool down. As maybe extremly hot rotors and freezing ice water are probably not the greatest for your rotors. It should not really be that much of a concern spraying your rotors as the rotors are designed to run hot while getting wet from the elements. But as the wheel is spinning, the rotor is once again heating up and cooling down evenly. It is not till you park your car and the rotor cools down and the pad retains heat is where you are warping in that one spot.

Now as for spraying you hot rotors. It is not the actual spraying of your rotors that can cause the rotor to warp(as they are designed to run hot and get wet)but the fact that your rotors are cooling down except where the pad makes contact and still retaining heat. The difference in temp can cause your rotors to warp but...
It has to be a perfact storm. The thicher your rotors are the hotter they have to be. Spraying your thin, hot rotors is not really the issue, but keeping you car parked for a long time after can be. Your blistering hot rotors that have been sprayed and cooled down and the pad contacting the rotor still hot in that one spot means that the rotors are not evenly the same temp. Having your car parked like this for a short period of time will not warp your rotors. But leaving your car parked like this long enough for the rotors to completly cool is not making your rotors happy. But again, unless your rotors are glowing red, sprayed with the coldest water ever possible and left to sit for a day. Just sprayin normaly hot rotors with water WILL NOT warp your rotors.

Long story short. If you do get your rotors blistering race track hot, drive around the block slowly with little brake and the moving air will cool your rotors enough to not warp. If you are not able to drive around the block and have to park immediately. Then just go back out to your car in about 15-20 minutes and pull down the e-brake and let your car roll forward or backward just enough so the hot pad is in a different spot on the rotor. I do this with my thin rotors and they are fine. I will soon be putting on my 4th set of pads to my one set of really thin rotors and I probably won't be changing my rotors untill they look like this.
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Old 07-05-2013, 04:01 PM   #30
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Thanks for all the help and the comments, I never heard of the bedding in process before, I will try to do it today and hope to remove some of the residue on the disk. Worst case, I'm gonna have to buy brand new rotors and pads and start fresh. I will do bedding in after I install the new set. I will post the results here.
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