Rotor Sizing?
Thread Starter
Racer
Joined: May 2016
Posts: 359
Likes: 153
From: Clinton, Illinois
Rotor Sizing?
Does any one know if there is a difference in rotor sizes when you have magna-ride option as opposed to not having it? My car is a 2006 LS2 base coupe with magna-ride
Race Director
Joined: Sep 2007
Posts: 16,557
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From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
Assuming the OP is asking about an un-modified car, that'd be correct, unless the original buyer ordered the stand-alone J55 option, which was available from '05-'13.
To know how the car left the factory, check the codes on the glovebox door. JL9 for the smaller solid rotors or J55 for the larger cross-drilled rotors that many call Z51, since some aftermarket suppliers referred to them that way and never bothered to change their catalog or website..
To know how the car left the factory, check the codes on the glovebox door. JL9 for the smaller solid rotors or J55 for the larger cross-drilled rotors that many call Z51, since some aftermarket suppliers referred to them that way and never bothered to change their catalog or website..
Race Director
Joined: Dec 2013
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- JL9 - Front 325mm/12.8"; Rear 305mm/12"
- J55 - Front 340mm/13.4"; Rear 330mm/13"
- J56 - Front 355mm/14"; Rear 340mm/13.4"
- J57 - Front 394mm/15.5"; Rear 380mm/15"
Last edited by Dano523; May 29, 2020 at 09:37 PM.
Drifting
Joined: Aug 2004
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Last edited by Trebor; May 31, 2020 at 09:06 PM.
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Burning Brakes
Joined: Apr 2017
Posts: 1,050
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From: Romeoville, IL
yup follow this. Every Auto store has this wrong. Their system just states with or with out mag ride. Autozone gave me GS rotors which are to large Orielys gave me base models. Amazon most are GS models with mag ride. Powerstop is the only one that listed the J55 13" rear rotors.
Race Director
Joined: Sep 2007
Posts: 16,557
Likes: 2,106
From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
yup follow this. Every Auto store has this wrong. Their system just states with or with out mag ride. Autozone gave me GS rotors which are to large Orielys gave me base models. Amazon most are GS models with mag ride. Powerstop is the only one that listed the J55 13" rear rotors.
My '08 with F55 had J55 brakes from the factory. I changed the rotors to the smaller JL9's and drilled them to match the same pattern as J55's. However, I retained the J55 rear caliper, which has a different size piston than the JL9 rear. The front calipers are the same for J55 and JL9.
Le Mans Master
Joined: Jan 2016
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From: New Mexico
2018 C6 of Year Finalist
Race Director
Joined: Sep 2007
Posts: 16,557
Likes: 2,106
From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
Weight reduction. Especially rotating weight. New JL9 rotors (all 4) weigh 67.4# vs 85.4# for the J55 rotors. I turned them to .010 over the low limit and then drilled them to reduce them another 6.5#. The shorter JL9 brackets saved roughly another 2#, but I can't find that exact number now. The smaller rotors allowed me to use '04-'06 GTO 17" spare wheels with 26" M&H skinnies on the front to save another 50# and a Deca 18# battery saved 17 more than the OEM battery. Then removing the front sway bar (13#) and draining the wiper fluid (12#), plus swapping the cast iron exhaust manifolds and cats to headers took more weight off the front end.
I saved weight in other areas too and tried to always arrive at the track with less than 1/4 tank of fuel. Paying close attention to small details is one reason I run 10's with just bolt-ons.
I saved weight in other areas too and tried to always arrive at the track with less than 1/4 tank of fuel. Paying close attention to small details is one reason I run 10's with just bolt-ons.
Le Mans Master
Joined: Jan 2016
Posts: 8,055
Likes: 2,694
From: New Mexico
2018 C6 of Year Finalist
