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^ Agreed! I have some slotted and drilled PasswordJDM rotors sitting at home waiting to be put on. I always thought they just look cool but now I'm more aware of what they could do for me.
 

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yes, thank you - now we can point people to your thread who claim drilled have better heat dissipation because off "less" surface area

If we still had rep i'd give you an 8ball if i could :laughing:
i can see how slotted and drilled can cool better though fluid dynamics and wet/brake dust braking. don't know how much an effect the less surface area to disperse heat helps during daily driving mode
 

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Actually, I got cross drilled and slotted rotors on my rear brakes.😳 But I bought the car from the dealership that way. (Previous owner had them put on I guess.)
I rather have them on the back anyways, the fronts do most of the stoping. The lesser of two evils I guess...
 

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well time to take off the powerstop drilled and slotted rotors from amazon. should i keep the ceramic pads over oem though?
 

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The only problem with the original post is that it was all people's opinion. Some very respectable ones, though. Unfortunately not one single person in that post reference any type of objective brake testing at all. In other words, zero citations or references.

I'm not pro or against drilled rotors. In fact I had mistakenly told many people the real myths of cross drilled rotors such as the myth "You only want holes that are cast." The truth is that there is no known rotor that actually casts the holes...not Porsche, not anyone. If you scour the internet you will not find a single document from Porsche or another manufacturer who states they cast these holes. Just think about how difficult it would be to cast holes like that into a rotor.

The other myth is that cross drilling increased temperatures instead of reducing them. People post their opinion that it is because of reduced rotor area. Actual brake testing does not bear this out to be true. Here is an ASE white paper on the matter...

http://www.tazcobra.com/SAE_2006010691_Synopsis.pdf

What the papers clears up is the following..

1. There is no evidence that any of the OEMs are actually casting holes in the rotors. They are called cross drilled for a reason. It would be extremely cost prohibitive and according to Brembo when they did testing on cast versus drilled they found no differences at all. It seems to have been internet rumor that XYZ companies cast their holes so they are better. What seems to be important is to chamfer the holes.

citation:
https://www.buybrakes.com/brembo/faq.html#q22

"Are discs with cast-in-place holes better than cross-drilled discs?
Brembo has extensively studied and tested cross-drilling versus casting the holes in place and found no significant effect on performance or durability."

2. Cross drilling has absolutely been proven to reduce rotor temps upwards of 10-20% and the difference grows the harder the braking/higher the speeds. That's quite a bit. Thats over 100 degree reduction in rotor temps in many cases.

3. There are downsides. There is significantly increased pad wear (20-50%) and there is an increased chance of cracks which could compromise safety. The recommendations are to find any other way to mitigate heat before cross drilling. Safer methods would be increasing rotor size, selecting a more efficient internal vane design, and improving brake ducting.

One technique the helps alleviate concerns about cracking is having the holes overlap so no uneven wear and "ribbing" occurs.

Just another bit of evidence to add to the thread.

Mike
 
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