Need Advice on Rotors!!!!
06-11-2010, 06:11 PM
#6
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Location: NJ
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Those don't look too bad. Monitor them..Take a look and see how the inner surface looks like. You might look into a set of slotted ones.
Check these out, these are toast! (not mine)
Check these out, these are toast! (not mine)
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06-14-2010, 06:21 PM
#9
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Almost new !
06-14-2010, 06:44 PM
#10
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Your rotors are fine. Replace if cracks join two or more holes or go right to the edge. If any crack is 10 mm or longer that too is a sign they need to be replaced.
06-15-2010, 05:17 AM
#12
Burning Brakes
From Porsche:
The condition of the parts can make replacement necessary under two criteria, depending on the wear of perforated brake discs:
1. Cracking in the holed (perforated) friction plate is in an advanced state.
2. Brake disc minimum thickness is not attained due to wear (material erosion due to friction). In practice, both forms of disc erosion occur.
Usually, it is necessary to replace the brake discs when they fall short of the brake disc minimum thickness. Only in rare cases (for long−term race driving brake loads / very high temperature fluctuations in the friction surfaces), the cracking and perforating can proceed so quickly that a premature disc change has to be performed. Visual inspection for cracks and evaluating cracks Perforation starter cracks arise through material fatigue due to frequent and extreme heat elongation fluctuations. These fluctuations in the disc temperature, which generally arise in racing, tear the perforations in a radial direction due to material fatigue (changing heat elongation conditions). For their part, these starter cracks allow a partial relaxation of the friction plate, so that the speed at which the cracks develop is very slow. The maximum permissible perforation crack length is 5 mm. The growth of the perforation starter cracks or a tearing of the rim of the friction plate worsens the smoothness of braking, decreases the disc strength and therefore makes a precautionary parts replacement necessary.
The condition of the parts can make replacement necessary under two criteria, depending on the wear of perforated brake discs:
1. Cracking in the holed (perforated) friction plate is in an advanced state.
2. Brake disc minimum thickness is not attained due to wear (material erosion due to friction). In practice, both forms of disc erosion occur.
Usually, it is necessary to replace the brake discs when they fall short of the brake disc minimum thickness. Only in rare cases (for long−term race driving brake loads / very high temperature fluctuations in the friction surfaces), the cracking and perforating can proceed so quickly that a premature disc change has to be performed. Visual inspection for cracks and evaluating cracks Perforation starter cracks arise through material fatigue due to frequent and extreme heat elongation fluctuations. These fluctuations in the disc temperature, which generally arise in racing, tear the perforations in a radial direction due to material fatigue (changing heat elongation conditions). For their part, these starter cracks allow a partial relaxation of the friction plate, so that the speed at which the cracks develop is very slow. The maximum permissible perforation crack length is 5 mm. The growth of the perforation starter cracks or a tearing of the rim of the friction plate worsens the smoothness of braking, decreases the disc strength and therefore makes a precautionary parts replacement necessary.
06-15-2010, 04:27 PM
#14
Burning Brakes
What I’ve posted is what Porsche says; however I’ve had my cracks up to 7mm before I changed the disks and all was ok. Yours look ok to me, for at least another 8K street driven “spirited” miles. Just pay attention to two cracks meeting or cracks extending to the rotor edge.
06-15-2010, 04:36 PM
#15
Burning Brakes
Why $520 for the right one and $540 for the left? That's odd? Also, that seems expensive to me. You should be paying about $170 for OEM rotors - each and $145 for OEM pads - each.