I've tried to search for this question in various places online. which way should the slots on a slotted rotor be?
Take for example, if you're looking at the top half of the front driver side brake rotor (12 o'clock position), should the slot start from the bottom left and go to the top right like this: / or should it the slot start from the top left and go to the bottom right like this: \ ?
seems like it would be like this: / to help "throw" the heat away from the center of the rotor towards the edge since the rotor would be turning counter-clockwise. but more often than not, i've seen it like this: \ which seems like it would direct heat to the center of the rotor.
Anyone have any hard facts about this?
Truthfully, it doesn't really matter.
What I do know is my friend just installed slotted rotors, and he wasnt paying attention, and installed the rear ones going the opposite direction as the front ones. haha.
I googled and found tons of pics of both installations.
I found this image that someone claims is to be installation instructions for some race brakes.
I guess when I had them a few years ago I installed them backwards.
Thats how mine are installed. I still think it doesn't really matter.
I agree it probably doesn't matter.
Unless the vented rotors have directional vanes. Then it matters. I read that on the internet so I can sound smart here.
the image is what i've seen on some high-end cars lately. I too installed them opposite of the image years ago. Good point on the directional vanes. thanks.
N Sperlo wrote:
Thats how mine are installed. I still think it doesn't really matter.
I think it does matter. A little. Having the rotors installed the way that picture shows makes the slots more likely to "scoop up" air as they rotate, which would ostensibly help cooling. And that's supposed to be one of the purposes of slotted rotors.
In reply to Sky_Render:
I see your point. I was thinking the opposite - "throwing away" the heat. But if you think about it in terms of physics, cool air moving across or towards the rotor is more likely than heat being "thrown" off of the rotor. The way I understand it is that the rotor also acts as a heat sink. So cooling the rotor with air to maintain temperatures within a desired range is the goal, not trying to shed the heat.
In reply to Sky_Render:
Everything matters a little, but yes, I would agreed.
formula747 wrote:
In reply to Sky_Render:
...
The way I understand it is that the rotor also acts as a heat sink. So cooling the rotor with air to maintain temperatures within a desired range is the goal, not trying to shed the heat.
This is exactly correct. Larger rotors are used on race cars for several reasons. The most obvious is that a larger rotor face means larger pads. Another reason is that larger rotors mean frictional forces are being applied farther from the hub, which means a greater lever arm and more torque available for braking.
But a less obvious reason is heat dissipation. Larger rotors have more surface area and thus radiate more heat than smaller rotors. This equates to longer pad life and less chance of boiling brake fluid.
