Originally posted by Mudvane
Sorry to tell you this but you just bought "fake cross-drilled" rotors. Real cross-drilled rotors are not drilled after being made... the "hole" are already present in the mold.
Drilling rotors creates microfactures around the holes that can lead to more major fractures.
If done incorrectly, than yes, that is correct. But if they are drilled correctly, than they are at no greater risk of getting cracks than a non drilled rotor.
And just a side note...
Cross-drilled does almost nothing for brake cooling. The main purpose is to save weight by removing material from the rotor...
Advanges of x-drilled rotors are as such
*decrease in weight (as you said)
*increased overall performance
*increased wet braking performance
*increased fade resistance
*increase in cooling (yup, it's true)
*decreases stopping distances
"There is only one way to prevent this sort of thing - following proper break in procedures for both pad and disc and use the correct pad for your driving style and conditions. All high performance after market discs and pads should come with both installation and break in instructions. The procedures are very similar between manufacturers. With respect to the pads, the bonding resins must be burned off relatively slowly to avoid both fade and uneven deposits. The procedure is several stops of increasing severity with a brief cooling period between them. After the last stop, the system should be allowed to cool to ambient temperature. Typically, a series of ten increasingly hard stops from 60mph to 5 mph with normal acceleration in between should get the job done for a high performance street pad. During pad or disc break-in, do not come to a complete stop, so plan where and when you do this procedure with care and concern for yourself and the safety of others. If you come to a complete stop before the break-in process is completed there is the chance for non-uniform pad material transfer or pad imprinting to take place and the results will be what the whole process is trying to avoid. Game over.
In terms of stop severity, an ABS active stop would typically be around 0.9 G’s and above, depending on the vehicle. What you want to do is stop at a rate around 0.7
to 0.9 G's. That is a deceleration rate near but below lock up or ABS intervention. You should begin to smell pads at the 5th to 7th stop and the smell should diminish before the last stop. A powdery gray area will become visible on the edge of the pad (actually the edge of the friction material in contact with the disc - not the backing plate) where the paint and resins of the pad are burning off. When the gray area on the edges of the pads are about 1/8" deep, the pad is bedded."
Taken from StopTech
Bendix recommends a break-in procedure as follows (but the above method is good too):
A series of controlled moderate speed stops (15-20 Stops from 30-0mph w/30 sec cool down) is required to properly "burnish" or break-in a new set of pads. During this initial stopping period, the process of lining transfer from the disc pads to the rotor surface helps condition the rotor surface to properly seat the brake pads. All pads are cured and ALL pads need to be burnished.