2nd Gen R56 Cooper S Most liked posts in thread: Slotted vs smooth rotors

Straight slots are more headache than they're worth on the track. I've run both, and there was absolutely no improvement over smooth discs. But the slots cause temperature gradients, which in turn can lead to uneven pad deposits, and the dreaded judder. Since going back to smooth rotors that issue is gone.

Supposedly slots that are curved or j-hooked are less prone to this, but straight slots are essentially worthless; modern pads don't have the gas buildup issue that gave pad kickback in the past, the cleaning ability of straight slots on the pad is more theoretical than practical. They seem to have a very nice placebo effect however.

 

For track use drilled rotors have the propensity to crack, that's why you'll see more guys running smooth or slotted rotors. slotted rotors have been said to help release gasses caused by braking and also help clean off the pad. Of course the main reason people go for anything other than smooth is to keep the brakes cool or to look cool.
I use slotted as do most of the guys in my car club. They have been excellent for hard stops especially. However much to do about braking is about the pad and you'll get a bunch of opinions on here but carbotech for me has been great and I drive about 90 miles a day like you half country and half interstate.

 

As has been mentioned unless your doing a track event or VERY hard twisty driving you don't really need drilled or slotted rotors. They look cool, but will wear your pads alittle quicker as well. Even at the standard Auto X event with a 45-60 second run your not on the brakes enough to really benefit I don't think, considering your usually only in 2nd gear so not going but so fast compared to a full out track event.. Also been mentioned it comes down to your pad more so then the rotor.. I run a cheap Centric rotor which is the same thing Ian Stewart has run and won championships with in the past..

 

Get slotted rotors if you like the look and styling, but they won't give you any performance benefit. Street driving doesn't involve the frequent hard braking scenarios that slotted rotors are intended to benefit.

 

if you want to learn more from an expert

The Brake Man - RotorTech

 

I would only get slotted unless you Auto-X or Track. The braking performance is definitely noticeable in a high brake loading environment, no so much on the street. Even if you're hitting the street "hard" like everyone says they are to sound like a bad-ass, I still would not get them. You aren't braking from 120MPH to 50 MPH on the street continually. Save your money.

If you're getting charged twice the price to slot the rotors that is nonsense.

 

Smooth rotors and Carbotech or Brakeman pads for me. :devil:

P.S. you a can have the best brakes money can buy and they still won't work well if you have poor tires.

 

They are surprisingly cheap if they're the brakeman rotors, much cheaper than many rotors that aren't near the quality. When you take them out of the box the first time, I'll guarantee they'll look better than anything you've ever put on your MINI from a quality standpoint, they look like they've been engineered rather than mass produced, if that makes sense.

I'm up to 4 (might be able to get 5) full track days on them (on tracks that are pretty hard on brakes) at the moment, which is far better than what I was getting before. Jan and Ian do better, but I'm admittedly not as good as a driver, but improving (I'm using the brakes less and less, in some places not at all where I had to before, as the car continues to get setup better and better). And I'm horrible on brakes (byt getting better), more my learning curve than anything else. I did crack a rotor once, but it looks like it was related to something other than the brakes (a failing hub). Despite that, that rotor was replaced at no charge--meaning the service from Brakeman/Jan is stellar--I seriously doubt there are too many other places that would have offered that (I didn't even ask either, just mentioned I'd cracked it, next thing I know a replacement was in the mail). Since fixing the hub and a rub issue along with it, it's been great.

They have a set that are quite a bit more expensive that I might try someday for kicks, they have the potential of lasting a full season or longer, but really, swapping out after or five events is not an issue IMHO, I'm doing better on rotors than other folks in MINIs who are running slower lap times and less HP.

The main reason I went that route was size--it's the only 12.19 (yes, 12.19!!!) inch diameter (0.81 inch width) kit that fits a 15 inch wheel. It was either that or go larger diameter, and I wanted to avoid that.

 

I use them, I like them & I'll buy them again. No drilled rotors for me.

 

Very true! some folks burn through their brakes & others don't, it's all driving style dependent. Drilled rotors are fine on a street driven car.

 

Metallic or Ceramic? How hard do you use your brakes? Don't forget to flush the brake fluid with high quality stuff. Many varying opinions on that too.

I use a ceramic pad with slotted rotors, love the lower dust. For me they work very well. Driving style makes a big difference, you need to evaluate your needs. I tend to not use my brakes that hard. I'm the kind of driver who likes to maintain momentum, & I'm not one of the late brakers. Exit speed not entrance speed.

 

Go with the slotted if you like the looks, no real world benefit for a daily driver. Pads will be the biggest performance choice. I have been running the Cool Carbon pads for some time now and love them. Tried the Hawk HPS and found them to be junk for my driving style.

 

Thanks Jan. that's a good read!

 

Rotors do two good things - provide something for the pads to grab onto and dissipate heat - and one bad - add unsprung weight. Brake design essentially seeks to balance these factors. Bigger rotors help the performance driver by dissipating more heat and providing more braking torque. Of course, the limit to stopping power is usually tires, but that's another internet rant.

The purpose of drilling rotors is to reduce weight. If you fit a huge rotor onto a Porsche that never leaves the garage when it's dark or raining, the extra weight will hurt ride quality. And since these cars will never actually see the track, there's no performance loss due to reduced heat dissipation, so they mount drilled rotors at the factory. Same with those AMG Mercedes - reduced weight helps ride quality over the speed bumps in the golf course parking lot.

Slotted rotors don't do much to reduce weight, but they do provide a better surface for pads to grab. Modern pads don't outgas, and if they do, it's all gone after you bed in the pads. Slotted rotors do a good job of cleaning the pads. This is helpful in the rain - that initial "dead pedal before the pads grab" feeling goes away with slots. And it's helpful on the track, when you're converting large amounts of expensive track pad material into dust. The slots help to clear the dust away from the pads. They cause a mild humming sound under braking, which can be slightly disconcerting to the uninitiated. The other benefit to slots is that they function like wear bars - no more slots, time to change the rotors.

Oh, and you'll pay a premium for slotted and/or drilled rotors. So unless you're trying to impress the Saturday morning Cars n Coffee crowd or "win" an HPDE lapping session, the price to performance benefit isn't worth it to most people. So if you're looking for a performance edge, get a BBK. If you like the looks, go ahead and pay a little more. Otherwise, just find the cheapest flat rotors that fit the car.

I happen to like putting Centric 125-series rotors on my friends' and family's cars because they're cheap and they usually qualify for Amazon Prime. Also, they seal the rotors in plastic so you don't have to wipe off any sticky rust-proofing oil. My brother is an instructor with BMWCCA, and he puts the same rotors on his track car for the exact same reasons - go figure.

 

I was going to post :idea: but then I saw what BThayer23 said which is what I was going to say... I only have one thing to add is that on the track car I use the slots starting to fade away as a quick and easy way to check rotor life, sometimes they get too cracked before then and sometimes not. For the rear rotors and on my street car centric blanks have been great and cheap! I do occasionally think the slots would look cool on the street car but then decide I would rather spend that money on making the track car faster or safer.

Some hardcore autoX folks (where the weight benefit is more useful than the ability to take heat) do run drilled rotors so much so that I believe there is a specific rule about how much material you can remove!

 

my rotors I have now have never cracked and Ian Stewart is brutal on brakes. Before I got what I have now he DESTROYED a brand new set of PFC rotors at over $800 in 1 day. Hauling a full weight Mini down from over 140mph repeatedly will do it until now.

 

I have wondered this same thing for quite a while.