OCA::DIY Motorsports

Holy hell, thank God I don't live where they salt the roads!

FixedWing

<center><img src="http://www.diecasting.org/design/case3/images/HeatCheckA.jpg"></center><p>
I spoke with my metallurgist father this morning. Apparently this is called heat checking. In time, the metal will start to crack in these areas. It is not corrosion.

The link below contains interesting information on heat checking.

I took the rotors off because of a lot of vibration through the peddle and noise. Not sure if this is the cause but I suspect so.

Stephen<ul><li><a href="http://www.eng-tips.com/viewthread.cfm?qid=127358">Cause of Heat Checking</a></li></ul>

FixedWing

No kidding... :-/

Imola Ghost

3 days after install. I don't know what to do, I've called them and told them about it and they told me to get some sand paper and rough up the rotor suface.

FixedWing

But I know that isn't my problem.

It could be yours if you didn't bed the pads correctly, if you used the stock pads and if you drive really hard.

Stephen

Andrew C.

<b>"If only a small amount of material has been transferred i.e. if the vibration is just starting, vigorous scrubbing with <u>garnet paper</u> may remove the deposit. As many deposits are not visible, scrub the entire friction surfaces thoroughly. <u>Do not use regular sand paper or emery cloth as the aluminum oxide abrasive material will permeate the cast iron surface and make the condition worse.</u> Do not bead blast or sand blast the discs for the same reason."</b><ul><li><a href="http://www.stoptech.com/whitepapers/warped_rotors_myth.htm">http://www.stoptech.com/whitepapers/warped_rotors_myth.htm</a></li></ul>

Andrew C.

Cast iron is an alloy of iron and silicon in solution interspersed with particles of carbon. At elevated temperatures, inclusions of carbides begin to form in the matrix. In the case of the brake disk, any uneven deposits - standing proud of the disc surface - become hotter than the surrounding metal. Every time that the leading edge of one of the deposits rotates into contact with the pad, the local temperature increases. When this local temperature reaches around 1200 or 1300 degrees F. the cast iron under the deposit begins to transform into cementite (an iron carbide in which three atoms of iron combine with one atom of carbon). Cementite is very hard, very abrasive and is a poor heat sink. If severe use continues the system will enter a self-defeating spiral - the amount and depth of the cementite increases with increasing temperature and so does the brake roughness. Drat!<ul><li><a href="http://www.stoptech.com/whitepapers/warped_rotors_myth.htm">http://www.stoptech.com/whitepapers/warped_rotors_myth.htm</a></li></ul>

ryoung

The first pic is not unusual for a rotor that sees the track, but ...

<img src="http://pictureposter.audiworld.com/17157/rotorcracks.jpg">

After about 1000 miles on track, this is the final result.

<img src="http://pictureposter.audiworld.com/17157/alcon_cracked.jpg">

FixedWing

Yes, this was what my father said. Next step would be cracking.

I'm really not sure that this is related to the vibrations I was getting though. Could be. But not sure..

Stephen

FixedWing

No. This is produced by heat. Cememtite states with transfer of pad material to the surface.