Brake Discs (Rotors) - Different Styles

[SuperDeluxe80]

drilled sucks rust get trapped in the holes and then they crack

[DJMC5ive]

It appears we have many scientists within the comments. :P

[BYCURE213]

slots also shave off burned material allowing for better braking

[TheOxTube]

@mossmotorscom cool video, one question though, you mention that heat is the #1 enemy of a brake disc. however if my disk brakes are at normal temperature say driving at 120kph and i brake just once very hard in an emergency stop will that one stop generate enough heat on that one stop to reduce braking efficiency during that stop? or are the slotted and / or drilled disks only good for repeated hard braking? thanks again!

[FatFred2U]

@TheOxTube The hard braking will heat-up the pad and rotor, which is generally a good thing since the heat will increase the friction between the pad ad rotor. However, the heat will migrate to the brake fluid, which decreases the fluid pressure and lessens the clamping force exerted by the piston: hence brake fade. Slots/holes on the rotor face increase the surface area of the rotor, which spreads the heat further from the swept portion and aids convection cooling: thus less heat in the fluid

[lordbemylight]

I wouldn't waste my money on the drilled/slotted rotors no matter how I drive because those rotors wear the pads out faster.

[jeffhanson1]

A brake shop mechanic tried to steer me away from going ceramic. He said he gets lots of people coming back complaining about warped rotors. I didn't listen. Sure enough, my Solara's original front rotors warped twice with just average braking for the most part. Back to semi-metallic for me even if they are more dusty.

[1fastnighthawk]

Why dont you try giving your big explanation to ferarri lamborgini brembo stoptech that slotted/crossdrilled discs do not work i think they will all laugh in your face .......owner of 2 vehicles with brembo slotted/crossdrilles discs and o yea if yours did crack next time buy the real deal not some homemade drilled rotors lmao!

[gundamduo20]

Well I now know to never buy anything from this imbecile.

do your homework on how drilled/slotted rotors affect braking before you post an "informative" video. You are making assumptions based on what they "seem" like they are adding to your brakes. Go look up the convection coefficient for air, and then look up the conduction coefficient for metal. tell me what that makes you think about...

[Sandeep9201]

could you reservice drilled rotors??? HELP

[827rover]

i thought slots biggest advantage is that they literally resurface the pads during every braking so they don't glaze and stay always fresh and clean

[meandmyevo]

well, the point of slotted rotors, is that when you get ON the brakes, the surface of the pads will get cooked and vaporized, like water being dropped on a hot pan. the gasses coming off the pads acts as a lubricant pretty much and severely limits the grip between the pad and rotor. the slots give the gas a way to escape the pad without killing the braking power.

Cross drilled rotors are for better heat dispersal, and slotted+crossdrilled rotors can do both, but are generally much more fragile.

[MeowSysTheCat]

No, slotted rotors were originally designed to help gasses dissipate from the rotor to provide more linear braking force (a la @meandmyevo), however slotted rotors eat brake pads because those slots act like razors shearing off pads.

You're best bet?

Vented (not solid) rotors are good for every day cars and in some cases (a la Aston Martin's and a few others manufacturers) can be used for performance.

X-drilled rotors (non-slotted) are best for 'driving your car, hard'

[gustavosserra]

Thanks for all your videos. I like the way you explain things, very clear. Keep up the good work.

[crosswire7777]

I think this video is misleading because it fails to mention the drawbacks of having slotted or cross drilled rotors, such as how they tend to warp or crack. A larger blank rotor beats out the slotted cross drilled rotor any day in performance and longevity. Not to mention that the latter has a smaller surface area.

[MisterBaz1]

Also, he says that the slots and holes are designed to 'cool' the rotors better. This is COMPLETELY FALSE.

They do NOTHING to aid in cooling.  They are specifically for when the pads are degassing under repeated extreme braking (race conditions).

The holes in the rotors can actually impeed the cooling vents in the rotor.

[MeowSysTheCat]

I am sorry, but you are completely wrong in this statement.

Slots are for gas dispersion. <-You'll see these (actual legitimate ones, not those on ricers) on track and race cars BECAUSE they actually get to a high enough speed that the slots actually disperse gases.

X-drills are for better heat dispensation.

Examples of X-drilled can be found on almost all Lamborghini's and Ferrari's, just to name a few.

[MisterBaz1]

Drilled was the original answer to pad outgassing. Slots were designed to help outgassing and remove any debris or glazed pad material from the rotor surface. Drilled rotors can actually have less cooling ability that strictly slotted rotors.

Drilled rotors almost always crack along the drilled holes when put under track abuse. Not a big deal when you replace them after every race or so.

Been-there-done-that.

[MeowSysTheCat]

This is only true in some cases @crosswire7777, you can find large vented (aka blank; and not solid) rotors on some Aston Martins, and on the Maserati Quattroporte (not to mention others) and they give very good braking; it all depends on the "quality, usage, and application". Large blank rotors are only good for so long until serious fade and heat begin to kill braking performance.

[jeffhanson1]

@crosswire7777 Goof point provided it's a high quality solid rotor, not check aftermarket/Chinese rotors. Not all rotors have the same disc thickness. Raybestos rotors for example are very thick with a thin vain in the middle. Cheap discs have a large middle vain but thinner discs.

[lilaznmage15]

@crosswire7777 Slotted and Drilled rotors tend to warp and crack because of calipers using one piston which presses against one side of the rotor warping the rotor as it spins. Brembo offers calipers with two pistons up to 8 pistons per caliper along with slotted or slotted and drilled rotors.

[crosswire7777]

@lilaznmage15 warping and cracks occur in any material (look at roads in cities that have cold winters and hot summers) from the dynamic changes in temperature. whether it's 1 piston or 8 piston, if you have a brake rotor go from (making up numbers) 500 degrees Fahrenheit down to 200 in a span of 20 seconds, the metal has expanded and contracted quicker than it would with a blank disc.

[lilaznmage15]

@crosswire7777 Sorry but I'm going to have to decide with slotted rotors. Last time I drove my car really hard, my rotors and pad almost over heated losing stopping power and increasing stopping distance, the ABS system even activated. The scariest part of everything was this event occurred in traffic on public streets.

I'd rather have less chance of break failure than longevity. Besides, drilled rotors are meant to keep the temperature down right?

[Whoppels]

@lilaznmage15 Why are you driving that hard in traffic on public streets? Sounds like you have some other issue.

Also, Crosswire is right. drilled/slotted is for show boaters, which is fine, because most people paying the money for a drilled and slotted rotor are just going to put-put around and show people how awesome they look. The downside is, that they may indeed look cool and work to provide cooling, but are also more likely to explode on the track and kill you.

[lilaznmage15]

@Whoppels It's just driving up to 120 mph and slowing down when traffic builds up.

[xstr33tr4cerx]

@crosswire7777 that is true but slotted is the best of the three cause it doesnt sacrifice and rotor strength and cools down faster