edyvw
$50 site donor 2025
ATE, Textar, Zimmerman, Pagid.
But by far my favorite, and quality-wise, most consistent is ATE.
Are drilled and slotted rotors worth the cost?
- Thread starter kitchbow
- Start date
But by far my favorite, and quality-wise, most consistent is ATE.
Mmm. Idk about the 2 piece part of it, but the math for weight - to - dissipation can be misleading. A Lighter rotor can drop temperature faster because it stores less thermal mass. This is different than dissipation. Dissipation is the rate by which it can vent off the heat. If two rotors with equal dissipation rates are made of different materials, they will both dissipate at the same rate, however the lighter ones will drop temps faster because they can’t store as much.
The leveling field here is this - the lighter rotor will reach higher temps on the same braking effort that the heavier rotor. They both ultimately capture, and thus must dissipate, the same amount of heat - only the lighter rotor with less thermal mass will hit higher temperatures during the process, and also see a more dramatic cooling rate, cooling down. Therefore, dissipation by weight is not the complete equation.
Dissipation effectiveness will favor surface area and texture and airflow, not thermal mass.
Now if we get very picky, lighter rotors as they if they get “stupid hot” (technical term for the day) will have a higher dissipation rate because they will have a greater thermal difference with the air passing over and through it, but I think that for what we are talking about, within more favorable and less extreme op temps, this doesn’t really apply.
*****
- Drilled rotors without chamfered surfaces are prone to crack
- Many drilled rotors are made as blanks and then drilled by a third party who may or may not care.
- Slotted rotors can wear pads down but can help resist glazing
- Slots can introduce some noise and or pulsing
- Slots are less prone to rotor cracks
Brake air ducting is a great alternative without compromising rotor type.
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Mic drop, if I've seen one.
Slotted rotors will or were designed to keep the brake pad face clean and dissipate heat. I'm sure in some instances they do help. The biggest reason that cross drilled rotors were used was lightness and the fact that alot of racing brake pads had outgassing when hot causing pad float. This isn't really an issue any longer.
I think you might be better off just buying performance/heavy duty pads instead. Take a look at performance cars sold new like 400Z and Supra etc, they have big brakes but the rotors are plain. So it seems like slotted/drilled rotors are kinda not necessary for hard driving, but quality rotors and pads are...
Mine are drilled and slotted oem MB. I notice the holes get clogged with pad dust. Don't know if it's self cleaning..
I dont have the white paper now but I they did some testing with directional vanes and if you have directional vanes they do a better job of cooling than drilled rotors.
Brembo?
While still expensive carbon ceramic rotors might be a possibility for some makes and models now, not just high dollar exotic cars.
edyvw
$50 site donor 2025
They are OK when it comes to regular aftermarket stuff. Still, prefer others.
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- Oct 3, 2023
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Since you're towing and moving heavy loads, brake pad compound is gonna be more important here, some brands sell severe duty semi-metallic pads for your application.
As for rotors there is some merit to slotted rotors as someone that formerly drives 100 miles per day encountering various road and weather conditions throughout the year, slotted rotors do help improve braking in wet weather conditions and steep downhill braking action compared to OEM plain rotors and pads. Then again the pads too make a difference so its hard to contrast when you have a combination working together.
As for Drilled & Slotted, I have run before on a daily driver but never on the track. Likely fine for street use on lighter cars but I'd avoid it on a towing truck as drilled holes could end up being a liability down the road should you start seeing heat checking cracks meaning more money down the line for a new set of rotors. Plenty of folks on youtube that do drilled and slotted rotors reviews that I have seen don't seem to complain much other than some saying cracks forming at the drilled holes after severe use cases.
I'd stick with slotted like EBC USR / GD rotors or something with a good pair of semi-metallic pads. I'm currently running Slotted & Dimpled rotors on both of my cars with semi-metallics pads and is very happy with them so far. Braking and modulation feels much better than OE and feels more consistent in places when you're driving up and downhill in repeated stops.
Slots>drilled but neither are necessary here. Save your money.
I do run slotted on my Sportwagen but no choice with the 2 piece rotors. Plenty of folks track blank rotors.
I actually like slotted rotors in climates where you can often get freezing rain.
I have had rotors freeze over - 32 degrees outside, rain/freezing rain - pressed the brakes, firm pedal, and absolutely no change in velocity, because the rain froze on the rotors and the pads were pressing on ice. I was on I-91 northbound trying to get off on I-89 in White River Junction - ended up merging back on and continuing north. I had absolutely NO brakes. That think layer of ice on the rotors makes an excellent lubricant, reducing the coefficient of friction to zero.
The slotted rotors allow that ice to be scraped off more quickly. Much safer. Same conditions in Vermont with a different car, initial no brakes, and half a second later - full brakes.
Interestingly - my 2005 S class measures rain, and gently applies the brakes periodically to keep the rotors dry and clean, ready for an instant stop.
The Mercedes factory rotors are drilled - by the way. Not sure if they would clear the ice as quickly in those rare conditions.
I bought EBC brakes (pads and rotors) for the truck - and they’re slotted. Wasn’t looking for slotted, but they worked well in the snow and inclement weather when I had it up in Vermont a couples months ago.
I have had rotors freeze over - 32 degrees outside, rain/freezing rain - pressed the brakes, firm pedal, and absolutely no change in velocity, because the rain froze on the rotors and the pads were pressing on ice. I was on I-91 northbound trying to get off on I-89 in White River Junction - ended up merging back on and continuing north. I had absolutely NO brakes. That think layer of ice on the rotors makes an excellent lubricant, reducing the coefficient of friction to zero.
The slotted rotors allow that ice to be scraped off more quickly. Much safer. Same conditions in Vermont with a different car, initial no brakes, and half a second later - full brakes.
Interestingly - my 2005 S class measures rain, and gently applies the brakes periodically to keep the rotors dry and clean, ready for an instant stop.
The Mercedes factory rotors are drilled - by the way. Not sure if they would clear the ice as quickly in those rare conditions.
I bought EBC brakes (pads and rotors) for the truck - and they’re slotted. Wasn’t looking for slotted, but they worked well in the snow and inclement weather when I had it up in Vermont a couples months ago.
I've have a pair on my 93 c1500 for 4 years and about 40k miles. Seem fine, I have towed probably about 5k or 6k miles out of those and have Wagner Severe Duty pads on them this whole time. No regrets.
4WD
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