Brake Rotors?
Thread Starter
Melting Slicks
Joined: May 2001
Posts: 2,143
Likes: 7
From: San Diego CA
Brake Rotors?
I have the Z51/J55 brakes. I was just cleaning the wheels and noticed the drilled holes seem to run "backwards" on the left side. I bought it used, its got 90K mike, so rotors have been replaced.
I replaced rotors on my C4 a bunch of times (in 250K miles). It dawned on me that I never paid attention which way the holes slanted. I looked at my C4, the rotors on both sides slant "forward". Probably by dumb luck.
So my questions are: 1) Does the direction the holes slant make any difference? 2) Are OEM brakes directional? I
I replaced rotors on my C4 a bunch of times (in 250K miles). It dawned on me that I never paid attention which way the holes slanted. I looked at my C4, the rotors on both sides slant "forward". Probably by dumb luck.
So my questions are: 1) Does the direction the holes slant make any difference? 2) Are OEM brakes directional? I
Racer
Joined: Jun 2004
Posts: 319
Likes: 40
From: Hemet CA
The holes should slant forward. If it makes a difference to you, replace with directional like StopTech. They have lots of options for drilled and slotted rotors and work great with their high performance pads. Hope it helps.
Race Director
Joined: Sep 2007
Posts: 16,557
Likes: 2,108
From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
The C6 J55 brake package never had directional (left vs right) rotors like the C5's. In addition processing the airflow different on each side in the front, the rear rotors were even more confusing, since the air ducts feed the rotor from the inside and the rotor intakes it's cooling air from the outside.
Strangely, the JL9 (base) rotors have post vs vane construction. By careful placement of the posts, the rotors handle airflow equally well regardless of rotation.
I swapped my J55 rotors & brackets for JL9's to save 18 lbs of rotating weight and drilled them with the same hole pattern as the J55 rotors to reduce the weight another 1.5 lbs. That effectively was equivalent to saving 23 lbs of dead weight while retaining the same appearance and improving the airflow.
Strangely, the JL9 (base) rotors have post vs vane construction. By careful placement of the posts, the rotors handle airflow equally well regardless of rotation.
I swapped my J55 rotors & brackets for JL9's to save 18 lbs of rotating weight and drilled them with the same hole pattern as the J55 rotors to reduce the weight another 1.5 lbs. That effectively was equivalent to saving 23 lbs of dead weight while retaining the same appearance and improving the airflow.
Race Director
Joined: Sep 2007
Posts: 16,557
Likes: 2,108
From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
