Do Performance Brake Rotors Have Better Cooling?

Do Directional Brake Rotors Prevent Brake Fade?

Do directional vaned brake rotors provide better brake cooling? In this video I test new brake rotors on my Honda S2000 to find out. I only changed out the front brake rotors, everything else is exactly the same (same brake pads front and rear, same brake rotors in the rear).

Equipment Used:

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[andrewnowakowski]

You did it wrong, when they say cooler they mean it looks better. a common mistake.

[nickf]

I can see what it is that you did wrong...you had the winter air still in the tires. you need to drain the winter air and put in the summer air so it keeps the blinker fluid cooler

[collarbonecam]

I think this is just a result of testing parts intended for the track vs parts for the road. People convince themselves that race parts must be better on the road because they are designed for harsher conditions but this refutes that. Very useful as I am going to need new rotors in the future and with my car being an old Lincoln, I never really thought I'd need performance rotors, but I really wanted them. But it looks like you've saved me some money! It may be a tricky one to test but if you're considering doing it, how dusty performance pads get would be extremely useful as I think that is what will do more for braking performance.

[bobbysenterprises]

I have heard that the slots or vents in performance rotors are not intended to cool the rotor. But rather to allow the vaporized brake pad gas off out from under the pad helping relieve brake fade. Also to help take heat out of the area between the pad surface and rotor not the rotor as a whole.

Interesting test and your work into it is commendable.

The smaller mass should have a faster temperature change rate. Heat up and cool down faster between applications

[trevorhoward]

As an ME this was a great video. Other factors to consider are friction as the stock rotors you tested looked to be used and the slotted rotors looked brand new. Generally rotors need to be "broken in" to the brake pads. If the same pads were used throughout the experiment they may have broken in to the stock set of rotors creating higher friction points on the slotted rotors. Incidentally came across this video looking for upgrades to my stock brakes.

[Spinattitude]

I know it takes a lot of work to do these tests, they are informative and interesting. Thanks for doing it!

[CaptainThirdGen]

nicely done test. Something to consider is that if the aftermarket rotors were brand new, perhaps they have a protective corrosion resistant coating (many rotors do for shipping) and these coatings usually take a while to burn off, and these coatings burn HOT. Just something to keep in mind.

[fromthegods]

I once sprayed WD40 on the brakes to clean them so they will brake better. Forgot to clean it off. Massive surprise at first intersection

[FireStorm]

You were likely not traveling quickly enough for the aerodynamic differences (if any) to take effect. On a track your speeds will near 100 mph, where the discs can quickly shed heat between severe braking events. Remember that cooling largely does not happen during braking, but rather immediately afterwards. At 40-60 mph you were likely not in a speed regime where the aerodynamic differences would appear - this would be like testing downforce at low speeds - the tests would say it has no effect, when really you just need to travel more quickly. Also, measuring temps right after braking does not reflect aerodynamic cooling efficiency because all you've done is built up heat, but not allowed the system adequate time to evacuate the heat. Even on the downhill test, the final braking at the end to stop the vehicle could skew your results. Instead, you would need to somehow perform a braking event, run the wheels at high speed, and then stop them again (without using the brakes) to see how well they cooled after the first braking event.

[HenkkaWRC]

Learning physics hasn't ever been this much fun. You're the best "teacher" EE!

[christophereskridge]

How about actual performance? Like stopping distances, brake fade?

[-jimmyjames]

the veins vent the pad gases away and prevent brake fade and essentially do a similar job to a wet tread tire pushing water center out. critically hot pads under pressure want to hover away from a flat rotor surface much like a hover craft generates thrust and hovers on its skirt. introduce veins, voila gaseous escapiest... anyone that races or drives very aggressively knows the sinking and sphincter puckering feel
that is brake fade.

[UtwoBed]

Absolutely, YES. I drive my E350 van hard and I kept warping the rotors. I bit the bullet and bought a set of performance rotors and I've never had a problem since.

[DeadsupraEE]

This and ChrisFix videos is all I need.

[rreidnauer]

I'm not sure you are taking all things into consideration. Rotor temperature alone may not be the sole determining factor of performance. What if the rotors are carrying away heat from the pads more efficiently? Or, with the slotting allowing gas to escape may be offering additional friction, resulting in the higher temperatures, but increased braking as well.

I'm not saying you're wrong. Just that, I'm not sure that you are right.

[AutoMiseng]

Actually the brake cooling can be maximized by the airflow. The slotted ( you called directional) rotor has a inverted hat design which helps cool faster. Your enginnering guess was right about the rotor weight (we called it heat mass) on stock rotor..the inverted hat design is better cooling design. Unfortunately the slot design does not helps as people think. This rather helps to remove debris and waters.. hope this helps

[bqcaldwell]

Ok, first, that’s probably one of the coolest vids I’ve seen in a while.
I’ve been toying with the idea of switching my ‘07 F150 brake rotors to slotted, but I’ve come to the conclusion, and this was sealed by this video, that:
1. It’d really only be for looks
2. Even though I’m always on the road, I rarely have big loads or tow anything
3. I’ve seen videos and articles mentioning brake pad & rotor wear INCREASES with slotted/drilled.
Thanks for this. Science rocks!

[Tommy.McLean]

but they're air cooled so shouldn't you brake then travel a little and see the difference in cooling between OE v. aftermarket? you would also think you'd need a specific brake pad with the directional rotors do increase the breaking and cooling but decreasing the coefficient of friction to run cooler.

[mattweeks]

I always thought drilled and slotted rotors are for expelling gas from the pads. The slotted rotors might be pulling more temperature out of the pads themselves, causing the rotors to get hotter. Would be good to do a test on the pads for a comparison.

[GaryWold]

That was very informative. Let's not forget that in addition to better operating temps under extream conditions. The mass 2.2 lb. rotating mass reduction is good for gains in mpg, acceleration, & braking distances in a competitive situation. Love your videos!