HarrierRX300

Hi guys,

I had a debate with a friend on the following:

Which direction are slotted rotors supposed to face? For example, if the calipers are closer to the driver, are the slotted rotors supposed to face towards the calipers when driving forward? Or if the calipers were in front, should the rotors aim away from the calipers, driving forward?

GSteg

iTrader: (15)

It depends on the vanes of the rotor. If they're not directional, then it wouldn't really matter.



The slots on the surface of the rotors are irrelevant.

rominl

iTrader: (4)

correct, the vanes are the key, NOT the holes or the slots.

and for that matter, all brands could be different. in fact, even within brembo on the same kit for the same car, you can see "different" hole directions front and rear

LiCelsior

iTrader: (32)

question i have to ask..does drilled and slotted really help with braking? i heard one is functional but the other is for eye candy but i forgot which one.

yusef

^^ I heard unless you track the car its useless for everyday driving, and is just there for show.

lighthalo

cross drilled and/or having slots on your rotors does improve performance (cooling/brake pad dust and wear) but not to the extent you would notice it during daily driving (or spirited driving for that matter)

so pretty much they're there for show unless you're going to compete with the car...

although.. i do agree they look cool (having cross drilled or slotted -- but not both) when done right (multi-piece rotors, non-ebay-looking cross drilled, etc)

HarrierRX300

Thanks for the input.

So how do I know how which directions the "vanes" are facing if it's in between in the rotors? Just wondering...

emoshun

iTrader: (11)

Insert popsicle stick...done.

4TehNguyen

iTrader: (1)

slotted/drilled rotors help ventilate small pockets of hot gas when the pad heats up during braking. If the rotor is flat like a regular car, there is no place for the gas to escape during braking until the brake pedal released. So it is to ensure maximum contact of the pad and rotor and use of the cars braking power. The slots are like irrigation ditches to channel gas away

http://auto.howstuffworks.com/auto-p...ke-rotors1.htm

HarrierRX300

"ask and you shall receive".... wow... thanks for the pic and quick response....

Much thanks...

Rjame

I just purchased some slotted and drilled rotors for my IS350 and when I replaced them I noticed the original front rotors had the cooling vanes facing the wrong direction so I had to recheck the figure above and yes they were wrong but when I installed the new ones I installed per diagram above.. Was it jus my vehicle or has anyone else come across this?

lobuxracer

iTrader: (2)

That article has some fundamental problems. Clearly they didn't talk to a brake engineer. Pads haven't had issue with out-gassing since they stopped using asbestos for pad material. Saying heat escapes faster through the channels is laughable. Slots are there to keep the pads clean and slightly reduce unsprung mass. Nothing more. Holes are just bad. There is no credible data to support them doing anything useful, and no one runs them on the track because they're no better and a lot worse than plain faced rotors.

The rotors (if they're from Toyota or Lexus) will be marked left and right. Do not ignore this and do not blindly follow instructions posted on the Internet about which way to mount your rotors. Toyota has a patent on their curved vane discs. If you do not install them correctly, they will run hotter. Does this mean anything to a street driver? No. You'll never know the difference even if you're foolish on the street unless you live at the top of a steep mountain and drive down it every day.



This shows the proper installation of the front rotors on the MkIV Supra. We argued about this on an email list many years ago and discovered Toyota got it right. Keep in mind, as soon as the disc is rotating, the outer edge has a higher linear speed than the inner edge. This guarantees the air flow is from the root of the disc to the edge, not the other way around.

dunocarmet

I heard unless you track the car its useless for everyday driving

KillaIS250

iTrader: (1)

From the research I did a long time ago, blanks are the best because they give you the most surface area for braking. Unless you drive a race car where the brakes are getting red hot, I don't believe slotted, drilled or both would really be beneficial. I had slotted rotors on my last car and the only thing I noticed was that it ate the pads faster lol.

dsp979

I just replace my tiny stock rotors/calipers in my 240SX with bigger rotors/calipers from a Q45. I also got slotted/drilled rotors instead of blanks, hoping these will give me enough braking once I take it back to Laguna Seca. The stock 240SX brakes were not enough for turns 2 and 11 on Laguna Seca.

To lobuxracer, I know you replaced the rotors on the ISF after you discovered cracks between the drill holes, what type of rotors did you go with?