VF84

weird that the internal fins point forward, rather than the customary backward. but who am i to disagree with both toyota and stoptech..?

oem front right


stoptech front left rotor

albis350

I had to buy the stock rotors once and they are different i noticed because they even had different price, this must be the meaning behind it got it straight from a Lexus dealer.

Gville350

iTrader: (10)

Some helpful rotor and vein insight :

"Most stock brake rotors employ a straight vein rotor design, whether columnar or staggered, because these rotor designs are cheap to produce. Cooling may not be superior to a curved vein design, but can do an adequate job givena non-abusive braking style. When installing this variety of brake rotor, there isn’t any way to get it wrong; orientation does not matter.

Curved or directional brake vein rotor designs, on the other hand, are very much orientation sensitive; they don't call them ‘directional’ for nothing. A curved vein brake rotor made for the right side of the vehicle must be installed on the right side of the vehicle,it’s as simple as that.

Many people make the mistake of installing a right wheel designated brake rotor on to the left side of the vehicle,and vice versa, because they do not understand how these curved vein rotors work in theory. Theythink thatthese brake rotor veins are supposed to act like air scoops to cool the brake rotor off, and this certainly is not the case. These curved veins are actually used to increase air circulation through the use of centrifugal force, and do so by creating a vacuum inside the brake rotor plate sandwich. Because of this naturally created vacuum, air isconstantly beingpulled past the brake rotor in question and cools the brake rotoras a result, through convection.

You could actually think of a curved brake rotor design to work much like a fan or turbine in function. Because of this fact, if you were to install a curved brake rotor on backwards with a rotor made for the opposite side of the vehicle, then the curved veins would cease to function as designed. Actually, purchasing a set of curved vein rotors and installing them on backwards is very much counterproductive, so it is important to hire a qualified mechanic that is aware of these installation details.

Jetfire

iTrader: (3)

^good info. learned something new today.

VF84

i am fully aware of the internal veins and functions, hence my post. unless i'm totally mistaken, most directional rotors have the veins swept backwards, so when u put a screw driver in, it should point towards the rear. i've installed many rotors, and even brembo ones which have "surface" slots and drilled holes "forward," the veins are still "rearward."

what i'm saying is the stock rotor and the replacement stoptech rotor both have the veins pointed forward, which is contrary to traditional orientation. look closely at the center of the stock rotor (1st pic). it has R stamped on it, three of them in fact. it is on the right side of the car, note location of caliper. the left rotor is the same, L stamps but veins points foward.

hoser813

iTrader: (1)

http://www.zeckhausen.com/how_to_pro...all_rotors.htm

VF84

^ yes, which is why i'm questioning the oem and stoptech rotor orientations...

Gville350

iTrader: (10)

I have sent an email to tech@powerslot.com to answer this issue. As a current Power Slot customer and user of slotted rotors up front on my '06 350 this creates an issue for me. I checked my rotors and indeed the directional veins point downward or towards the front of the car. The opposite of everything we've read and been told to do. So I've inquired as to what happened at the plant...whether this was a mis-labeling of the right and left rotors or if this was done on purpose. I've asked for their explanation on what they did and why.

I'll let you all know what they say. I've linked them to this thread as well.

Gville350

iTrader: (10)

A tech named Pat had this to say :

"Lexus/Toyota has a rather special design for the vanes of their directional rotors…and they operate on a different theory than most. Instead of providing a relatively easy path for air to be drawn from the inside of the rotor outward…like a centrifuge, they use a “C” shaped vane, who’s purpose is to accelerate the air as it travels further towards the outer diameter of the rotor and force it out of the rotor. This patented design works extremely well.

Even though they appear to be labeled backwards, they are correct."

I replied asking for a cut-out view/picture of these "special" rotors.

Gville350

iTrader: (10)

Wow, he replied quickly with this :

Hoac

I love reading about this kinda stuff... hella engineering there!

VF84

silly fluid dynamics

let's hope stoptech used the same design...

thanks for finding the info gville! that was awesome

lobuxracer

iTrader: (2)

Funny how the same stuff keeps coming up years later. We had this same argument on the old MkIV email list in the late 90's. Bryce Dana pulled out a fan engineering book and figured out not only did Toyota do it right, but it's not just a gimick. BTW, veins carry blood, fans have vanes. Here's a blast from the past - New Car Features for the 1993 TT Supra:

Alpinam3

All I have to say is that I had no idea there would be such different opinions about brake rotor air flow veins. I'm not an engineer but have worked as a pro mechanic at a time in my life and have good mechanical aptitude. Since I can't prove or disprove air flow veins pointing back or forward I will have to take what I read about it.

It would be interesting to put one rotor on one front wheel each in different air flow vein direction. Go do some hard breaking and measure with an infrared pyrometer and see which rotor is hotter.