Stock Rotors are Directional.
Thread Starter
Race Director
Joined: Apr 2003
Posts: 19,352
Likes: 654
From: Tampa, Florida
Stock Rotors are Directional.
Just a little FYI for all of you who may not know.
I decided to put Z06 brake pads on my '03 coupe. As recommended by the forum I picked up new rotors from NAPA. When I was at the counter the guy said, "you need left or right or both?" I said, "they're the same." He said, "they have different part numbers." So, whatever, I went home with new rotors. The difference is in the cooling vanes. They are angled versus perpendicular. So I do the brake job and install the rotors.
For whatever reason I had the wheel off and noticed the vanes were angled so they wouldnt scoop are in. Dam, so I swapped the rotors real quick. Well, the next day I'm doing a rotor/caliper paint test (more on that later) and notice the factory 'right' stamping and look at the vanes. They point the other way!!!! It turns out I had them installed correctly the first time. Well, I'm off the swap then again. It turns out the vanes are designed to pull are in from the center area near the hub versus pulling air in from the outer rim. Oh well.
I decided to put Z06 brake pads on my '03 coupe. As recommended by the forum I picked up new rotors from NAPA. When I was at the counter the guy said, "you need left or right or both?" I said, "they're the same." He said, "they have different part numbers." So, whatever, I went home with new rotors. The difference is in the cooling vanes. They are angled versus perpendicular. So I do the brake job and install the rotors.
For whatever reason I had the wheel off and noticed the vanes were angled so they wouldnt scoop are in. Dam, so I swapped the rotors real quick. Well, the next day I'm doing a rotor/caliper paint test (more on that later) and notice the factory 'right' stamping and look at the vanes. They point the other way!!!! It turns out I had them installed correctly the first time. Well, I'm off the swap then again. It turns out the vanes are designed to pull are in from the center area near the hub versus pulling air in from the outer rim. Oh well.
Burning Brakes
Joined: Dec 2004
Posts: 1,234
Likes: 2
From: New Jersey
Ignore the holes, it really doesn't matter what direction they rotate in. The pictures are to show the direction of the internal vanes and the slots on the face of the rotor. Those must rotate in the proper fashion for the rotor to be effective.
http://forums.corvetteforum.com/show...post1549577331
In street driving it's not that big a deal. But on the track you will see 10-15% higher temperature on the rotors going in the "wrong" direction.
Last edited by Mighty-Mouse; Feb 1, 2005 at 08:18 AM.
Racer
Joined: Aug 2004
Posts: 315
Likes: 1
From: Bakersfield California
When I did mine I noticed that they were different part numbers. So, I only did one side at a time and compaired it to the stock stamped rotor that I was removing. I did not look right to me at the time either but after checking I found out the same thing you did. I was just happy that I did not have to take it all apart again.
Premium Supporting Vendor
Joined: Aug 2001
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From: King George VA
On the C5/Z06 (stock or OEM replacements) they are directional. I've read that GM has made all the C6 rotors the same so one side will be backwards on the C6.
Easy way to tell if they are correct on the C5/Z06 as you put them on is to look straight down at the top of the rotor. The vanes should "point" rearwards.
You can visualize this looking at the first pic posted by Mighty Mouse above. That rotor would be a driver's side rotor being viewed from outside the car. You can see the top of the vanes pointing right, or backwards towards the rear of the car.
The reason for this is that the vanes act as a centrifugal pump as they rotate and pull air from the center out to the outer edge.
Easy way to tell if they are correct on the C5/Z06 as you put them on is to look straight down at the top of the rotor. The vanes should "point" rearwards.
You can visualize this looking at the first pic posted by Mighty Mouse above. That rotor would be a driver's side rotor being viewed from outside the car. You can see the top of the vanes pointing right, or backwards towards the rear of the car.
The reason for this is that the vanes act as a centrifugal pump as they rotate and pull air from the center out to the outer edge.
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From: King George VA
Originally Posted by coast7
I just did some brake work yesterday and noticed my stock rotors were stamped with LR, RR, etc. Nice to know!
coast7
coast7
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Verdad Gallardo
Safety Car
Joined: Sep 2001
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From: Wilmington NC
Originally Posted by jim2527
Just a little FYI for all of you who may not know.
I decided to put Z06 brake pads on my '03 coupe. As recommended by the forum I picked up new rotors from NAPA. When I was at the counter the guy said, "you need left or right or both?" I said, "they're the same." He said, "they have different part numbers." So, whatever, I went home with new rotors. The difference is in the cooling vanes. They are angled versus perpendicular. So I do the brake job and install the rotors.
For whatever reason I had the wheel off and noticed the vanes were angled so they wouldnt scoop are in. Dam, so I swapped the rotors real quick. Well, the next day I'm doing a rotor/caliper paint test (more on that later) and notice the factory 'right' stamping and look at the vanes. They point the other way!!!! It turns out I had them installed correctly the first time. Well, I'm off the swap then again. It turns out the vanes are designed to pull are in from the center area near the hub versus pulling air in from the outer rim. Oh well.
I decided to put Z06 brake pads on my '03 coupe. As recommended by the forum I picked up new rotors from NAPA. When I was at the counter the guy said, "you need left or right or both?" I said, "they're the same." He said, "they have different part numbers." So, whatever, I went home with new rotors. The difference is in the cooling vanes. They are angled versus perpendicular. So I do the brake job and install the rotors.
For whatever reason I had the wheel off and noticed the vanes were angled so they wouldnt scoop are in. Dam, so I swapped the rotors real quick. Well, the next day I'm doing a rotor/caliper paint test (more on that later) and notice the factory 'right' stamping and look at the vanes. They point the other way!!!! It turns out I had them installed correctly the first time. Well, I'm off the swap then again. It turns out the vanes are designed to pull are in from the center area near the hub versus pulling air in from the outer rim. Oh well.
It would also be couterproductive to try to force air to the center as that would be fighting centrifugal force.
I label each rotor as soon as I get them to make sure I don't get in a hurry and put them on the wrong side.
Next time you are at a car show with a bunch "show rotors" feel the vanes and see which way they point. I, usually, manage to find a couple of cars with the rotors on the wrong side!
Also have found some on tech inspects for track events.
Burning Brakes
Joined: Aug 2000
Posts: 1,132
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From: Morganton, NC, USA
Several C6 owners on the C6 side of the forum are really pizzed at Chevy because they have the same exact rotor on the left front and the right front. They probably wouldn't have noticed if it weren't for the spiral cross-drilled hole pattern. Some have been told by Chevy that it really doesn't make much differance for a street driven car. Whatever else they also told owners, they are not getting the correct rotor for one wheel. What was that book by DeLorian, "On a clear day you can see General Motors"? 
Instructor
Joined: Aug 2004
Posts: 244
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OK so why is it every car I see around town has there rotors going in the wrong direction? I was starting to wonder if I put mine on backwards but they are stamped lf rf rr lr. Or are the ricers and other high performance cars rotors holes drilled in reverse direction that the fins are cast? Or is this just the new cool look, to be azz backwards? 
Burning Brakes
Joined: Jan 2004
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From: RPV CA
Originally Posted by Mighty-Mouse
http://forums.corvetteforum.com/show...post1549577331
In street driving it's not that big a deal. But on the track you will see 10-15% higher temperature on the rotors going in the "wrong" direction.
Pro
Joined: Mar 2002
Posts: 632
Likes: 0
From: Enterprise AL
Originally Posted by C54DAZ
OK so why is it every car I see around town has there rotors going in the wrong direction? I was starting to wonder if I put mine on backwards but they are stamped lf rf rr lr. Or are the ricers and other high performance cars rotors holes drilled in reverse direction that the fins are cast? Or is this just the new cool look, to be azz backwards?
zo6vettepilot
Team Owner
Joined: Jul 1999
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From: Buy USA products! Check the label! Employ Americans
Just picture the vanes that close together spinning that fast there wouldn't be much scooping happening that's why they go the other way and create vacuum to draw the air out. That is why spindle ducts blow the air IN to the center to let the vanes pull it out.
Le Mans Master
Joined: Jul 2002
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From: Slave to the evil empire
Cruise-In V Veteran
St. Jude Donor '04
Originally Posted by John Shiels
Just picture the vanes that close together spinning that fast there wouldn't be much scooping happening that's why they go the other way and create vacuum to draw the air out. That is why spindle ducts blow the air IN to the center to let the vanes pull it out.
Think centrifugal force and you'll understand it better.
Drifting
Joined: Jul 2004
Posts: 1,370
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Originally Posted by Mighty-Mouse
http://forums.corvetteforum.com/show...post1549577331
In street driving it's not that big a deal. But on the track you will see 10-15% higher temperature on the rotors going in the "wrong" direction.
Drifting
Joined: Dec 2004
Posts: 1,295
Likes: 236
From: Oshawa Ontario
Originally Posted by runamuk
Think centrifugal force and you'll understand it better.
Now on those pictures posted, it appears that both of those slotted/cross-drilled rotors are going "backwards"?
Are the internal vanes still pointed rearward like the stock ones though?
Otherwise, it would seem they're not going to be working effectively?!