Last week we talked about how long you can run rotors after they begin cracking. The type of rotor you use can play into how long they last. A question I often hear is “What type of rotors should I get?”
Long story short: If smooth rotors are working for you, GREAT. If you are having one of a couple possible issues, slotted may help. Save the drilled rotors for cars-n-coffee crowd. YES, I know some supercars come with them, that doesn’t mean you should. Keep reading to find out why.
Rotors are there as a place for the pads to do their job. There may be minute differences in pedal feel between smooth, slotted, and drilled.. but not much. If you are driving and having a problem with stopping power, rotors are the LAST place you should turn. If your car can’t lock up the brakes, look at your pads. If you lock up your brakes too easily, check your tires. Spongy pedal? Re-bleed the system.
Often I hear: “But I know someone whose brakes worked way better with upgraded rotors” – This may be the case if their previous rotors weren’t bedded correctly, over-torqued wheels, bad hubs, or perhaps they put new pads on and forgot to tell you.
If you are new to the track and prepping your car, you do not need to upgrade to drilled or slotted rotors.
Smooth rotors, or “blanks” are what the name implies, smooth. For many cars, these will do just fine on track. If you are using them without issue, continue to do so. They are also the cheapest, so replacing them in time will be less money than the alternative options.
My Spec Miata is admittedly very easy on brakes, but a full season of racing and HPDE with Hawk DTC 60’s and Toyo RR’s is not easy work. My smooth rotors hold up just fine, with just a bit of heat-checking showing after a year of events.
Slotted rotors are the choice for track and racing cars that aren’t getting what they need from smooth rotors. These are typically the faster, heavier cars whose brakes need to stop much more than a miata. This doesn’t mean that you need slots if your car weighs over X weight and makes over Y power, again… if your blank rotors are doing the job, keep them.
What do the slots do?
The slots give a place for debris to escape, avoiding unwanted pad deposits on the rotor. The slot edges wipe, clean (or shave) the pad surface which helps prevent unwanted deposits on the pad surface as well. However, this will shorten the life you get from your pads.
If you can’t shake a warped feeling pedal with your blank rotors and you can see deposits on the pads or rotors, a set of slotted rotors may help prevent the buildup. However, know that this feeling could also come from over torqued wheels or improperly bed brakes.
Drilled/ Drilled and slotted Rotors:
Do not run drilled rotors. Walk around the field of a car show and you will see plenty of cars with drilled rotors. Walk around the paddock for a race or track day and you will see smooth (blanks), or slotted rotors… with maybe a few cars with drilled rotors here and there.
The internet is filled with a lot of mixed information about drilled rotors, the important thing is to look at WHO is saying what. Typically only bench racing forum jockeys and cheap rotor salesmen are pushing for anyone to “upgrade to” drilled rotors on a track car. Are there any advantages? Properly drilled rotors provide much of the same advantages of slotted. Are there disadvantages? YES. Drilled rotors are much more prone to cracking, and typically do it much sooner than their smooth and slotted counterparts.
Drilled rotors were designed over 70 years ago to help pad gasses escape under heavy braking. Modern pads do not off-gas anywhere near like they used to.
Some supercars come with drilled rotors… You can bet that they are not simply the “Drilled” option available for your Altima on Rockauto, those rotors are quite expensive (and still crack sooner than their drilled or slotted counterparts). Many performance brake companies either do not sell drilled rotors, or recommend them only for customers seeing minimal track use.
Why is the demand for drilled rotors still there? Why do some manufacturers still deliver new cars with them? In my under qualified opinion: it’s mostly for the bling factor. Rotors diameters are HUGE and getting larger, and wheels are getting more and more open… so those giant rotor faces need to be sexy to their target audience.
I’ll stick with my $17 blank rotors. These are tempting though…