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SLotted rotors? Any good or costhmetic only?

K

kickaxeguitars

CEG'er
Joined
Jul 12, 2007
Messages
67
Do those slotted rotors really work? I think they look cool as hell but are they an improvement over OEM? If not, what is a better choise for performance?
 
For a street car, slotted rotors will not change the performance of your brakes in a perceptible manner. The only thing you will notice is faster pad wear. Slots on race car rotors scrape the surface of the pad and keep it free from glazing and contaminants to keep the braking surface consistant under severe usage.

On a street car, the only reason to choose slotted or even drilled brake rotors is for appearance.
 
i have drilled and slotted and i can tell you they do nothing other than wear my pads FAST. BUT the rotors are always way cooler than blank rotors. I'm going to go back to blank soon.
 
SVTJON87 said:
i have drilled and slotted and i can tell you they do nothing other than wear my pads FAST. BUT the rotors are always way cooler than blank rotors. I'm going to go back to blank soon.
Click to expand...

i ahve cross drilled and slotted rotors for the look, but i do feel i get better grip when its wet out with them, and i ahvent noticed any difference in pad wear:shrug: i dont usually brake alot i guess!
 
The real reason for slots and drilling

The real reason for slots and drilling

The real reason for slotting a rotor is to scrub off the boundary layer (very thin layer of air) between the rotor and brake pad. When the rotor is turning it carries air with it, then when the brakes are applied, this air has to move out of the way in order for the brake pads to start braking. Without slots, the air acts as an air bearing (a pretty good one at that) until the heat from friciton finally boils the air off (yup it happens) and the pads finally touch the rotors.

But at normal running and the speeds even the fastest contour can achieve you would never notice the difference

Just simple physics.
 
andreslobo said:
The real reason for slotting a rotor is to scrub off the boundary layer (very thin layer of air) between the rotor and brake pad. When the rotor is turning it carries air with it, then when the brakes are applied, this air has to move out of the way in order for the brake pads to start braking. Without slots, the air acts as an air bearing (a pretty good one at that) until the heat from friciton finally boils the air off (yup it happens) and the pads finally touch the rotors.

But at normal running and the speeds even the fastest contour can achieve you would never notice the difference

Just simple physics.
Click to expand...

This entire post is completely and totally wrong. Good god, where did you come up with this from? I mean seriously, can you come up with one single source that would publicly state this? Let alone a credible source? lol.
 
andreslobo said:
The real reason for slotting a rotor is to scrub off the boundary layer (very thin layer of air) between the rotor and brake pad. When the rotor is turning it carries air with it, then when the brakes are applied, this air has to move out of the way in order for the brake pads to start braking. Without slots, the air acts as an air bearing (a pretty good one at that) until the heat from friciton finally boils the air off (yup it happens) and the pads finally touch the rotors.

But at normal running and the speeds even the fastest contour can achieve you would never notice the difference

Just simple physics.
Click to expand...


Best post EV3R!!! :laugh: Don't get me started with the "physics" of it.
 
Didn't cross drilled rotors come out when asbestos pads were around - I though asbestos pads created gas when they heated up warranting the holes in the rotors to vent off the gases... :shrug: Or I may be just completely off base here...
 
Who is correct?

Who is correct?

It depends who you believe and maybe your training, education, and experience. The disc drive in your computer depends on a very good air bearing to 'fly' the head a few microinches above the disc surface. When I worked on disc drives we took great pains to ensure that the air bearing was maintained. The very same forces are at work when a pad tries to come into contact with a rapidly rotating rotor, this sets up an air bearng. Many methods including slotting rotors were designed to collapse the air bearing. In the early 90's some brake manufacturers were using multiple pistons in calipers with the leading edge piston smaller in diameter to increase the pressure at the leading edge of the pad to boil off the boundary layer quicker to reduce the lag between application and hard braking.
 
i dont think the wheels ever rotate fast enough to really create an air bearing thats a problem. even at top speed in the contour the wheels are only going to be spinning at about 2500RPMs. disc drives (im assuming your talking about your average PC HDD) spin over 3 times that speed (which im sure you know).
 
andreslobo said:
It depends who you believe and maybe your training, education, and experience. The disc drive in your computer depends on a very good air bearing to 'fly' the head a few microinches above the disc surface. When I worked on disc drives we took great pains to ensure that the air bearing was maintained. The very same forces are at work when a pad tries to come into contact with a rapidly rotating rotor, this sets up an air bearng. Many methods including slotting rotors were designed to collapse the air bearing. In the early 90's some brake manufacturers were using multiple pistons in calipers with the leading edge piston smaller in diameter to increase the pressure at the leading edge of the pad to boil off the boundary layer quicker to reduce the lag between application and hard braking.
Click to expand...

The only situation ever to be remotely similar to what you are trying to talk about relates to drilled rotors and pad outgassing from many years ago. Many many years ago, racing brake pads had compounds in them, that when subjected to extreme heat, would degrade into gases right at the friction interface between the pad and the rotor. This phenomenon was known as "outgassing". basically, the pads were generating thier own "air bearing" right on the friction surface. Drilled rotors were developed to give the gases a way to get away from the pad surface. It has been many years since pads that have issues with outgassing have been available.
Brake systems apply several orders of magnitude more pressure than can be generated from ambient air between the pad and the rotor. It isn't even considered during the design of brake systems, because it isn't a factor.

Multi-piston setups with dissimilar piston sizes are designed to reduce tapered wear of the pad, and have NOTHING to do with the air boundary layer. When a pad is forced against spinning rotor, there is a torque effect on the pad, that can lead to on end wearing faster than the other, dissimilar piston sizes are designed to alter the pressure distribution on the pad to reduce this tendancy to wear unevenly.

Seriously, if you don't know what you are talking about DO NOT GIVE ADVICE ON THE SUBJECT.
 
KyleQ said:
Didn't cross drilled rotors come out when asbestos pads were around - I though asbestos pads created gas when they heated up warranting the holes in the rotors to vent off the gases... :shrug: Or I may be just completely off base here...
Click to expand...

It was during that time, yes, but I'm pretty sure the gases weren't from the asbestos itself.

loggerbomb said:
So what IS the right answer?
Click to expand...

See my first post in this thread.
 
Rara said:
It was during that time, yes, but I'm pretty sure the gases weren't from the asbestos itself.
Click to expand...

Ok - I knew it had to do with older brake pad components - just figured it was the asbestos :crazy: So I wasn't completly off my rocker :laugh:
 
Air bearings depend on rpm and rotor diameter

Air bearings depend on rpm and rotor diameter

While disc drives now days spin at 5400 and 7200 rpm they are much smaller in diameter than a brake rotor. The velocity at the greater diameter of a brake rotor is similar to the velocity of a disc drive, thus it does create an air bearing. Actually air bearings are set up at relatively slow velocities.
 
andreslobo said:
While disc drives now days spin at 5400 and 7200 rpm they are much smaller in diameter than a brake rotor. The velocity at the greater diameter of a brake rotor is similar to the velocity of a disc drive, thus it does create an air bearing. Actually air bearings are set up at relatively slow velocities.
Click to expand...

And yet, it still doesn't factor in to an automotive brake system, not even a little bit.
 
lol at this thread. He had me going there for a sec...





but your both wrong. Drilled and slotted rotors were engineered to be lighter and to decrease rotating mass. Ultimately making your car accelerate and decelatrate quicker. Thats why alot of times you see race car drivers remove the break system completely.



:rolleyes:
 
If it were described as the gaseous and particulate boudary layer built up by friction between the pad and rotor suface....I'd buy into it. But air bearing....?
 
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