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      04-23-2014, 08:34 PM   #23
sawzall
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Originally Posted by Bill N View Post
I don't have any idea if the cryo process resulted in the improvement...maybe they just use a better rotor...I agree, it sounds like voodoo. In any event, changed rotors, problem went away.

But...you are saying that if a rotor were to warp, it would first have to be melted?
Kinda. Enough force would need to be applied to the rotor (in this cause heat), that move the crystal lattice within the metal. Don't think of this as turning the rotor into a molten lump though.

Enough force (e.g. heat, pressure) has to be applied to a metal to cause the crystal structure to move across one another within it. This friction creates heat and causes deformation of the metal. But this can only begin when enough force/heat is applied. But you're talking about temperatures over 900C. Few high end race pads can withstand 700C let alone 900C. Pads will melt sooner than a rotor will (which is why pad deposits can happen).
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      04-23-2014, 09:06 PM   #24
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Quote:
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Kinda. Enough force would need to be applied to the rotor (in this cause heat), that move the crystal lattice within the metal. Don't think of this as turning the rotor into a molten lump though.

Enough force (e.g. heat, pressure) has to be applied to a metal to cause the crystal structure to move across one another within it. This friction creates heat and causes deformation of the metal. But this can only begin when enough force/heat is applied. But you're talking about temperatures over 900C. Few high end race pads can withstand 700C let alone 900C. Pads will melt sooner than a rotor will (which is why pad deposits can happen).
Interesting, thanks for the reply. Way outside my expertise, but I naively would have guessed that another possible source of warping would be an uneven application of heat that would cause one part of the rotor to expand more than others, thereby deforming the rotor.
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      04-24-2014, 11:03 AM   #25
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Been driving like this for a week now. Rebedded the pads. Steering wheel still shakes when braking....
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      04-24-2014, 11:21 AM   #26
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Here are pad deposits on my old 08 M3 which are the dull area that you can see.If you check the runout in those areas they will be out of spec and can take a few weeks of driving to get rid of.These shook big time but cleaned up and stayed on the car as long as I had it.

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      04-24-2014, 03:05 PM   #27
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Interesting, thanks for the reply. Way outside my expertise, but I naively would have guessed that another possible source of warping would be an uneven application of heat that would cause one part of the rotor to expand more than others, thereby deforming the rotor.
What you're describing would be how a rotor could warp. Only issue is that iron is good at conducting heat, and given the mass of the rotor (and the fact that it is rotating/cooling constantly), it would be extremely hard to build up the necessary heat in a small spot.
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      04-24-2014, 03:12 PM   #28
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Been driving like this for a week now. Rebedded the pads. Steering wheel still shakes when braking....
Stock pads? Mine didn't clear unless I used more aggressive track pads.
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      04-24-2014, 03:43 PM   #29
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Quote:
Originally Posted by sawzall View Post
What you're describing would be how a rotor could warp. Only issue is that iron is good at conducting heat, and given the mass of the rotor (and the fact that it is rotating/cooling constantly), it would be extremely hard to build up the necessary heat in a small spot.
Not if you do not cool your brakes before you park or come to a complete stop.If I had to stop suddenly like during a Red Flag situation,that is usually when I have had uneven pad deposits.
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      04-24-2014, 05:16 PM   #30
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Not if you do not cool your brakes before you park or come to a complete stop.If I had to stop suddenly like during a Red Flag situation,that is usually when I have had uneven pad deposits.
Absolutely you'd get pad deposits. Warping your rotors could be slightly possible, but if your rotors ever got that hot, you better have your nomex on!
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      04-24-2014, 06:14 PM   #31
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These are a floating rotor so warpage is very unlikely unlike a one piece rotor used on most cars.
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      04-25-2014, 05:56 PM   #32
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The rotors were replaced for free.
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      04-26-2014, 05:29 AM   #33
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^ good news
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      04-26-2014, 05:22 PM   #34
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^ good news
Thanks Bobblehead C:, are you going to the rfd meet?
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      04-26-2014, 07:08 PM   #35
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I will definitely try. Certainly won't be there at 3pm but likely be there closer to 4pm ... if everyone has not taken off.


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Thanks Bobblehead C:, are you going to the rfd meet?
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