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Old 05/11/2013, 03:10 PM   #1
importsusa
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Default BRAKE ROTOR INFO 101

So you're wanting to install your own OEM or Aftermarket rotors or have a shop do it.....well, here's some info that will benefit all. The article below should shed some light on the common question WHICH WAY DO THEY GO? lol

Thanks to Paul Z. Racing for providing us this article:

Which Way?
How to properly install plain, slotted or drilled brake rotors
by Dave Zeckhausen


Directional vs. Straight Vane Rotors

Most "normal" cars come with straight vane rotors, with internal cooling vanes that extend straight from the center of the rotor outward, like spokes on a wagon wheel.
(See drawing on lower right) These rotors are not as efficient at cooling, but they are less expensive to manufacture and car dealers only have to stock a single
part for both sides of the car.

Some higher performance cars come with "directional rotors", which have curved or tilted internal cooling vanes. These curved vanes pump more air through the rotors, resulting in improved cooling efficiency. Thus, there is a left and a right rotor.
When the directional rotors are properly installed, these internal vanes should lean toward the back of the car
- as shown in the diagram on the lower left.




Slotted rotors

As with the plain rotors discussed above, the internal vanes should lean toward the back of the car.
The direction of the slots on the outside of the rotor do not dictate whether the rotor is a left or a right. For rotors with slots machined in the same direction as the internal cooling vanes, the slots should lean toward the back of the car.
For rotors with slots machined in the opposite direction as the
internal cooling vanes, the slots should lean toward the front of the car. Bottom line -
don't use the slots to decide which side to mount the rotor. Pay attention to the internal cooling vanes.

For slotted rotors with straight internal cooling vanes, the direction of the slots is totally up to you and what you think looks best. In this case, there is no wrong answer.



Drilled rotors

It is not possible to tell if a drilled rotor is installed properly, simply by observing the drill pattern. Different manufacturers use different patterns with spiral "arms" that appear to lean in either direction, regardless of the internal cooling fin orientation.
For example, StopTech AeroRotors, used on their big brake kits, have a drill pattern that appears to lean to the front of the car. Porsche OEM rotors have a drill pattern that appears to lean to the back of the car. In both cases,
the internal cooling fins are properly oriented, leaning backwards. But the drill pattern is opposite.
This is why Porsche mechanics often install StopTech big brake kit rotors backwards, despite the big "L" and "R" stickers on the rotors! They're relying on the drill pattern, rather than the direction of the internal cooling vanes.

As with slotted rotors, one must check the direction of the internal cooling vanes in order to determine the proper orientation of drilled rotors.



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Something else I wanted to add for reference (although it is mentioned above already) that would help you determine whether you have a straight vent or curved are the part numbers on box.
When a rotor is specifically designed to be installed on the right or left side of vehicle it will have a different part number. So for (example:) lets say you ordered a set of rotors for a 00 Type R and the numbers are 3296....well, both boxes will say 3296............
but if you ordered some front rotors for a porche and (I'm using a random number) use part number 14356 but the other box uses 14357, that will basically tell you those rotors are specific to a side.
Most aftermarket manufacturers out there have been slowly but surely adding stickers to the rotors (even when they are uni-directional) so that 20 million customers aren't asking them which way they go or have people point out that the rotors are on backwards.
If the vents are uni-directional (as stated above) it is up to the installer to put them in whatever direction looks best.......both ways will keep brake dust and heat away (unless you bought some super cheap pads...dust will be visible).

Hope this helps others understand a little more on what to look for so they aren't mis-informed.....again thanks to Paul Z. for this great bit of information which has been around for a long time now!!

Last edited by importsusa; 05/11/2013 at 06:15 PM.

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Old 05/16/2013, 01:14 AM   #2
jh4dc
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Default Re: BRAKE ROTOR INFO 101

Great article! Bottom line pay attention to the internal cooling vanes and part numbers. Got it

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Old 05/16/2013, 05:56 AM   #3
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Default Re: BRAKE ROTOR INFO 101

Quote:
Originally Posted by jh4dc View Post
Great article! Bottom line pay attention to the internal cooling vanes and part numbers. Got it
Exactly, I was glad to have been able to find this article after many years of knowing this info. Sucks that people get misinformed about these and end up spending money that didn't need to be spent.

For the most part Honda/acura and most brands need not worry about the issue since they are straight vane......which is cost effective on our end in the long run.


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Old 05/21/2013, 10:35 AM   #4
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Default Re: BRAKE ROTOR INFO 101

This is great info

Always thought it was from the direction of the slots/drills direction.


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Old 05/22/2013, 08:39 AM   #5
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Default Re: BRAKE ROTOR INFO 101

Quote:
Originally Posted by mike03 View Post
This is great info

Always thought it was from the direction of the slots/drills direction.
Lol nope, I thought the same back in 1998-99 when I first saw them being installed on a Honda in Florida. Fast forward to 2001 when I first did them and I got stuck and started searching for some answers and found this out from way back......figured it would help others understand that on mist Honda/Acura's the direction of the slots or drilled holes don't matter.....you could face them forward or back......mainly because if the straight canes in the rotor. If the Type R would of had the other type of vanes to assist in cooling efficiency...THEN the rotors would be specific to one side instead of having the same part numbers. This is unique and cost effective to have on our cars as opposed to a Porsche which is high end of course.

Last edited by importsusa; 08/18/2013 at 07:05 AM.

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Old 05/22/2013, 06:24 PM   #6
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Default Re: BRAKE ROTOR INFO 101

Hmm that explains while working on a Mercedes or BMW I was concerned about the slots/drilled pattern on the rotors. One side appeared to going the wrong direction then checked the other side and was going right direction
but came to a conclusion that it was the way the manufacture installed them lol

Until later you posted this, and now everything makes a lot more sense lol


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Old 05/23/2013, 03:53 PM   #7
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Default Re: BRAKE ROTOR INFO 101

Great post! It's good to see someone on here knows what they are talking about!

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