I recently purchased drilled and slotted rotors from rotorpros, and was wondering if they were put on right. I've seen numerous cars with drilled and slotted rotors, but they all are in different directions. How do I know if they are in the right direction?

it is confusing - but it is not the direction of the slots or drills (as different manufacturers do then in different direction - and all have 'their' reasons) but it's the direction of the vanes inside the rotor - inbetween the outer surfaces.

you want them 'scooping' air into the center of the rotor when moving forward - if that makes sense?

23898

Here is a pic of the front drivers side. The slots are going towards the rear of the car.

here is what I mean - this is my passenger side - the internal vanes have a slight arc to them forward and down - which helps move air into them when they are spinning in the move forward direction.

Quik, with all due respect, that is wrong, or at least your explanation is confusing enough to appear wrong. The vanes inside the rotor should expell air (from the center toward the outside) when moving forward, not draw air in. This reinforces the effect caused by centripetal force, and is actually the same way that "squirrel cage" blower motors work. They push air from the inside out. Trying to do the opposite is ineffective, because you will be working against the centripetal forces on the air.

For reference, please see the following FAQ at the Stop Tech website: "How do I tell what direction the rotors go on the car?" (http://www.stoptech.com/tech_info/faqs.shtml#16). They have cutaway diagrams so that you can visualize the vanes inside (as opposed to the slots or drill pattern on the surface).

right you are - there are 3 different ventilation types in use - straight or curved vanes and now 'pillars'.


Both straight vanes and 'pillars' are non-directional - but the curved vanes are directional.

Here is the Brembo explanation:

Curved vane disc should be installed with the vanes running back from the inside to the outside diameters in the direction of rotation.

Orienting the disc in this manner, creates a centrifugal pump. The rotation of the disc causes air to be pumped from the center of the disc, through the vanes, and out through the outside diameter of the disc. This enhances the disc’s ability to dissipate heat. On some OEM applications, this standard is not satisfied: the use of directional discs means to manage two codes (left and right) per axle with some extra cost therefore it happens that a car manufacturer can use the same disc with curved vanes on both sides, losing part of the benefit in balance with lower costs.


However - the instruction sheet I have with the Brembos I put on my Supra (installed two years ago) - say exactly the opposite.... and the picture of the install is exactly the opposite... hmmmm....

Now it looks like going with the pillars (non-directional) is the latest thing....

good catch