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05 V/corsa/shifter/bushings/stealth tune/cai/19inch hre's
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Discussion Starter #1
i just put them on...it looks like my pattern rounds torwds the front...shouldn't it round torwd the rear:hmm: ...
 

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'04V, '05V, '06SRT8, '10V, '13ZL1, '12 V, '16 Z06 SC757
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I asked James the same thing when mine were installed. They are not directional. All the rotors were the same pattern for both sides of the vehicle.
 

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'05 CTS-VM 51 track days in Maggied V & 82 in Atom 2 in Volt
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As far as the slots/holes it doesn't really matter, some prefer forward sweeping and others rearward. However there is some thinking that it may be beneficial to have the slot wipe the pad in a manner that will discharge to the outer diameter using centrifugal force, thus rearward. tomato/tom-auto

However if the interior cooling veins are not vertical, (most mass produced are straight so they can only cast one), then they should run sweeping backwards this produces less centrifugal fan (wind) generated HP demand.
 

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Some additional data to mull over in the age old controversy; drilled, slotted or plain rotors...

Attached are details from the #16 CTS-VR of Max Papis. These are of driver-side front and rear so forward rotation is counter-clockwise. Of note... not drilled.

Also, I spoke with the head mechanic at the Bondurant school. His findings were that anything that relieves metal from the rotor contributes to early failure. They stick with plain for durability.

Supposedly, the most durable drilled rotors are not drilled at all. The holes are cast in. Some Porsche rotors are manufactured this way.
 

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There is a lot of confusion out there regarding the rotor’s rotational direction.
First, let’s look at the rotor casting itself, without drilling or slotting.
There are basically two types of cooled rotor castings.
With cast pillars that separate the two disks (stock CTS-V).
With cast vanes between the disks.
The cast pillar type can be mounted any side/direction.
The vane type has to be mounted so that the vanes rotate to "suck" air from the inside out (just like a turbo). Therefore, the vanes should curve to the back of the vehicle (Fig 1). This means that the left and right rotors have to be different (e.g. KVR).
Drilling
Holes in a pillar type rotor are most likely random. But even if it creates a pattern, the installation direction is uncritical.
Holes of the vane type will often follow the vane’s direction. Of course, direction is still determined by the vanes.
Slotting
Slotting is done to release gasses from the pad and allow them to escape.
The idea is that when the pad sweeps over the slot, it starts to push the gasses from one end of the slot toward the other end.
Now the important part, and the part that most people do not realize, is that if the slots would be pointing back (just like vanes) the pad would hit the slot almost broadside and the gases could NOT escape properly at the end of the slot (Fig 2). Therefore, the slots have to rotate toward the front of the car (opposite the rotation of the vanes) (Fig 3). Slotting a pillar type rotor will make it directional, meaning left and right are now different. However, on a slotted pillar style rotor people often install them in a way to simulate vanes - that is pointing back. BUT this is incorrect! The vanes will point the other direction as the slots. This is where the confusion lies.
Slots on a vane type rotor are determined by the direction of the vanes (that is opposite).
Next time you are on a track day or auto-x pay some attention to the cars there. You will be surprised how many Guys got it wrong - installing slots pointing backwards.
 

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2017 Camaro ZL1; 2011 CTS-V sedan; 2004 Lightning
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"The wheels on the V go round and round..."

That about sums up my knowledge.
 

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'05 CTS-VM 51 track days in Maggied V & 82 in Atom 2 in Volt
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I stand corrected on direction of slot, however a centrifugal fan will work in either direction because you are basically flailing the air out from center to perimeter. The difference is that a forward facing fan will incrementally require more HP as it increases revolutions. A backward faced fan will get to a certain point and cease to move more air and HP demand so no use in wasting HP at top speed.

https://energy.navy.mil/publications/pnl/fanbi.doc

http://www.baer.com/Support/TechTips.aspx?TechTipID=2
 

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05 V/corsa/shifter/bushings/stealth tune/cai/19inch hre's
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Discussion Starter #9
also on the front...one goes one way...and the other goes the other way...the back...both are the same...i took it to caddy...they said thats how it is...they even showed me another set...i dont know..:annoyed:
 
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