Slotted rotors?
Thread Starter
Joined: May 2007
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From: Cara De Panocha, Aguada, Mexico
Slotted rotors?
Hi, I just wanted to know if slotted rotors make a dramatic difference and if theyre really worth it?I have a 97 civic ex coupe. I know they look very nice though 
Junior Member
Joined: Jun 2007
Posts: 45
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From: Boca Raton, Fl
Re: Slotted rotors? (doood)
If u have ceramic pads they will help get the pads hot and working well faster but really make no difference after the pads have warmed up. Alsos if u autocross its going to help becuse it will take a few runs to heat up the pads really good.
Honda-Tech Member
Joined: Sep 2006
Posts: 686
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From: Peterborough, ON, Canada
Re: Slotted rotors? (civic_saints1)
Well, the slotted rotors supposedly cool the surface down better and allow the gases created between the pad and rotor to vent. However, theyre also very hard on pads compared to blanks. Unless youre pounding the brakes repeatedly like in a roadracing scenario they wont do much but look pretty. I worked at a race shop, and even on theyre heavy comaros and vettes, they used blanks.
Member
Joined: Apr 2005
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From: MN, United States
Re: Slotted rotors? (Raw B)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Raw B »</TD></TR><TR><TD CLASS="quote">Stick with blanks. More surface area=more braking power. Try searching. There is a good write up about how shitty/needless drilled and slotted rotors are.</TD></TR></TABLE>
MiG-21 superfan
Joined: Mar 2001
Posts: 8,628
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From: near the ocean, Moderator City, NJ
Re: Slotted rotors? (Raw B)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Raw B »</TD></TR><TR><TD CLASS="quote">Stick with blanks. More surface area=more braking power.</TD></TR></TABLE>
that's a confusing generalization...
perforated rotors have more surface area than blanks...they cool down faster. they also are lighter than their full faced counterparts.
if executed properly, like that with Brembo drilled rotors, you should not have durability issues since the hole placement is chosen with vane position and other factors considered.
anyway, here is some very interesting info regarding this question as it came up before on h-t and erupted into a bunch of crap-
from Bob Chmelka from Race Tech, Brembo's sister company who handles race equipment and high-end street stuff...
"Interesting posts from 'arm chair physicists' not looking at all of the factors.
(A little background on myself: I have a BS in Physics & a BS in Mechanical Engineering from Arizona State Univ. I worked for AlliedSignal in the Materials Dept & then at their foundry making blades & wheels for jet engines.)
For a single stop a smooth rotor would probably out perform the drilled rotor, of course a drum brake will out perform any rotor brake system during such a condition, because on a single stop appreciated heat is not the issue. Total contact surface area between the friction material and the drum or rotor is the key to that single stop. (But then again a single stops is not an ideal condition in this context of daily spirited driving) So, let's talk about practical applications here. (like said daily spirited driving) Multiple stops and drum brakes over heat and fade away. Continuing to the subject of disc systems. The cooling ability of the rotor becomes key with multiple stops. The drilled rotor when done correctly will cool better than the smooth rotor by ~150 degrees. This cooling keeps the brakes from fading as readily (something that needs to be considered (too much heat) when speaking about coefficients of friction), extends the life of the pads, does a very light scrubbing off of pad glazing and helps enhance wet condition braking."
He also continued during a phone call today with a few additional points.
-Cast in holes are a cheap, inefficient and risky way of introducing holes into a disc. Proper drilling is a superior technique. This is for many reasons: one is there is more risk for gaps in the casting near the ceramic rods used for such holes and these can become amazingly dangerous for use at that point. He also said pieces/ bits of the ceramic rods can find themselves into the casting and make for stress risers, totally compromising the rotor.
-He also added that if drilled rotors were such a risk to have on a street car (referring to claims that they can fall apart to the point of danger, etc), Brembo would not make them...additionally, Porsche would not have used them on their competition cup cars PRE-ceramic era if there were risks to running drilled rotors....
-Brembo is not a fly-by-night company and doesn't make products they have to run from. There is an incredible amount of liabilty risk with this particular segement and they have invested immeasureable time and money to ensure that this does not become an issue with their products and performance is of paramount importance.
-He also added that performance Mercedes models use drilled rotors to help deal with one specific issue- brake fade that can quickly rear it's ugly head when trying to repeatedly stop a powerful AND heavy vehicle. It has little to do with aesthetics and everything to do with performance.
that's a confusing generalization...
perforated rotors have more surface area than blanks...they cool down faster. they also are lighter than their full faced counterparts.
if executed properly, like that with Brembo drilled rotors, you should not have durability issues since the hole placement is chosen with vane position and other factors considered.
anyway, here is some very interesting info regarding this question as it came up before on h-t and erupted into a bunch of crap-
from Bob Chmelka from Race Tech, Brembo's sister company who handles race equipment and high-end street stuff...
"Interesting posts from 'arm chair physicists' not looking at all of the factors.
(A little background on myself: I have a BS in Physics & a BS in Mechanical Engineering from Arizona State Univ. I worked for AlliedSignal in the Materials Dept & then at their foundry making blades & wheels for jet engines.)
For a single stop a smooth rotor would probably out perform the drilled rotor, of course a drum brake will out perform any rotor brake system during such a condition, because on a single stop appreciated heat is not the issue. Total contact surface area between the friction material and the drum or rotor is the key to that single stop. (But then again a single stops is not an ideal condition in this context of daily spirited driving) So, let's talk about practical applications here. (like said daily spirited driving) Multiple stops and drum brakes over heat and fade away. Continuing to the subject of disc systems. The cooling ability of the rotor becomes key with multiple stops. The drilled rotor when done correctly will cool better than the smooth rotor by ~150 degrees. This cooling keeps the brakes from fading as readily (something that needs to be considered (too much heat) when speaking about coefficients of friction), extends the life of the pads, does a very light scrubbing off of pad glazing and helps enhance wet condition braking."
He also continued during a phone call today with a few additional points.
-Cast in holes are a cheap, inefficient and risky way of introducing holes into a disc. Proper drilling is a superior technique. This is for many reasons: one is there is more risk for gaps in the casting near the ceramic rods used for such holes and these can become amazingly dangerous for use at that point. He also said pieces/ bits of the ceramic rods can find themselves into the casting and make for stress risers, totally compromising the rotor.
-He also added that if drilled rotors were such a risk to have on a street car (referring to claims that they can fall apart to the point of danger, etc), Brembo would not make them...additionally, Porsche would not have used them on their competition cup cars PRE-ceramic era if there were risks to running drilled rotors....
-Brembo is not a fly-by-night company and doesn't make products they have to run from. There is an incredible amount of liabilty risk with this particular segement and they have invested immeasureable time and money to ensure that this does not become an issue with their products and performance is of paramount importance.
-He also added that performance Mercedes models use drilled rotors to help deal with one specific issue- brake fade that can quickly rear it's ugly head when trying to repeatedly stop a powerful AND heavy vehicle. It has little to do with aesthetics and everything to do with performance.
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