Cross Drilled vs. Slotted which is better???

[Loco Honkey]

Proffs and books aren't always right. I had an ASE teacher tell me that a lower profile tire will *ALWAYS* handle better than a higher profile tire. I also have a book that recommends cutting springs vs. stiffer springs for performance applications.

I'm an ASE Master Tech. I hold ASE Certifications in everything but diesel engines. Your instructor is wrong.

Not every pad is carbon metallic, true, but I dare you to find a mass produced pad that has any organic material in it.

WTF are dippled rotors?

BTW- Towards the end, your caps lock got hit as you pounded away at the keyboard to spew forth that festering belch of wisdom.

 

[K2e2vin]

Originally posted by 89_starter@Jan 3 2004, 09:38 PM
The main brins of brakes is to create heat. THAT IS HOW THEY WORK! FRICTION=HEAT and FRICTION MEANS STOPPING. AS A MATTER OF FACT MY INSTRUCTOR TELLS ME THAT DIPPLED ROTORS ARE THE BEST, lESS FADE, MORE SURFACE AREA.

no heat is a byproduct of friction. if they wanted heat then they wouldnt have vented rotors. if you want to create the most friction, you want the most contact area, and blanks have the most, second comes slotted, and last is drilled.

 

[bcman]

I think he means dimpled rotors, which would have small holes that don't go all the way through the rotor.
some manufacturers have gotten around the fractured rotor problem by casting the rotor with cross-drilled holes already in place. So if you absolutely must have holes in your rotors, make sure they're cast, not drilled.

 

[asmallsol]

yes, the brembro brakes that are on porsches and Ferraris are Forged with the holes already there so that there is no real reduced level of strength. However, 95% of the aftermarket rotors out there (including the shitty brembro slotted and crossdrilled ebay rotors) start out as blanks, then a diffrent company buys them then drills them.


I just read yesterday in the autoweek with the main feature being the new c6 corvette. One of the main engineeers was talking about the diffrent packages that were going to be offered and one was designed for the weekend warrior. Stiff springs, stiffer sway bars, stiffer shocks, and cross drilled brakes. Then he went on to say that the rotors trully served no true purpose except to stand out and look cool.

 

[89_starter]

Well to generalize this all, New pads and rotors are the best. and in saying that i mean you can have the fancy brakes but they are old that can't out stop cheap autozone brakes. Worn struts can add up to 20 feet of stopping distance. And my instuctor is not wrong. He is a huge race head, hell he is even freinds with Bobby Rahal ( team Rahal representing Columbus Ohio). He bought Bobby's 2000 Docati ( i think I'm spelling that right).Slotted rotors are for gas fade. Where do you think the friction material goes? it doens't just disappear? BUt any way us arguing ain't helping. I say slotted rotors and Bendix titinium metillic pads work for me and the stopped real well. BUT..... I might be wrong.

 

[89_starter]

Originally posted by Loco Honkey@Jan 3 2004, 09:44 PM

I'm an ASE Master Tech. I hold ASE Certifications in everything but diesel engines. Your instructor is wrong.

HEy I totaly respect that Also cuz I know the long tests that you had to take to get to that status.

 

[StyleTEG]

Pads still do produce some vapors when they are heated up, a small layer of the pad is going to burn off and that will create vapors.

How-ever, high quality brake pads should have a slot in the surface to allow those vapors to escape. So gas/vapor is not a reason to use cross-drilled brakes.

Cross-drilled brakes, when done correctly WILL increase surface area. (NOT SWEPT AREA, which is different).

Its simply finding the surface area of a cylinder and removing the top/bottom face.

Surface area = 2*pi*r*h - 2*pi*r^2

If the radius of the drill is equal to the thickness of the rotor, you gain no surface area. If the radius is smaller, you gain surface area. Finally, if the radius is larger you lose surface area.

Example 1:

2 * 3.14 * 8 * 8 – 2 * 3.14 * 8^2 = 401.92 – 401.92 = 0

Example 2:

2 * 3.14 * 6 * 8 – 2 * 3.14 * 6^2 = 301.44 – 225.08 = +76.36

Example 3:

2* 3.14 * 10 * 8 – 2 * 3.14 * 10^2 = 502.4 – 628 = -125.6

Surface area radiates heat, so more surface area does result in faster cooling. However, it is at a sacrifice of MASS, which is what determines your thermal storage.

Cross drilling does not just reduce weight.

However, you would be better off going to a larger rotor which has more surface area and mass. That way you don't have to worry about cracking. The stock Honda rotors don't have a ton of thermal storage to begin with, why drill some away?