Brake System Identification
Thread Starter
Le Mans Master
Joined: Jan 2006
Posts: 5,620
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From: Orlando FL
Brake System Identification
I should know this but just have not been in the vett circle long enough. I have a stock 94 and need to know what kind of brake system I have. The question came up when I tried to look at new rotors. I am familiar with the J55 name (but what does it mean) and the light duty but how can I find out which one I have. Is there a standard one that's the norm. I know this has got to be a basic question. 
Last edited by pcolt94; Jun 1, 2006 at 02:00 PM.
Drifting
Joined: Oct 2005
Posts: 1,944
Likes: 24
From: Hurst Texas
St. Jude Donor '07-'08-'09
Unless something has been done to them the '94 spec was for 11.9 In Disc front and rear....changed in '95 to larger front. Is that what you were looking for?
You may want to search threads but I thought I read some folks going to 13in (J55/ ZR1) drilled rotors front and rear without any other apparent mods.
You may want to search threads but I thought I read some folks going to 13in (J55/ ZR1) drilled rotors front and rear without any other apparent mods.
Last edited by DFWLCJ; Jun 1, 2006 at 02:06 PM.
Thread Starter
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
It's not a ZR1 which you seem to have related to the J55 system. It is stock and nothing has been done to it. I beleive it is the 12 inch rotors.
OK - I got it figured out. It's not oviously the J55 system which is on the ZR1. So it is the other one called LIGHT DUTY BRAKE SYSTEM RPO: JL9, anti lock with rear disk brakes. I'm set, Thanks
OK - I got it figured out. It's not oviously the J55 system which is on the ZR1. So it is the other one called LIGHT DUTY BRAKE SYSTEM RPO: JL9, anti lock with rear disk brakes. I'm set, Thanks
Last edited by pcolt94; Jun 1, 2006 at 02:42 PM.
Burning Brakes
Joined: Jan 2006
Posts: 847
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From: Colorado Springs CO
Originally Posted by pcolt94
I should know this but just have not been in the vett circle long enough. I have a stock 94 and need to know what kind of brake system I have. The question came up when I tried to look at new rotors. I am familiar with the J55 name (but what does it mean) and the light duty but how can I find out which one I have. Is there a standard one that's the norm. I know this has got to be a basic question. J55 is a heavy duty system. I believe it has to do with the rotor size depending on the year.
Le Mans Master
Joined: Sep 2003
Posts: 5,874
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From: Littleton CO
Originally Posted by Ttime
J55 is a heavy duty system. I believe it has to do with the rotor size depending on the year.
Originally Posted by DFWLCJ
You may want to search threads but I thought I read some folks going to 13in (J55/ ZR1) drilled rotors front and rear without any other apparent mods.
Last edited by jrp; Jun 1, 2006 at 03:25 PM.
Drifting
Joined: Oct 2005
Posts: 1,944
Likes: 24
From: Hurst Texas
St. Jude Donor '07-'08-'09
I'm under the impression that the calipers and caliper brackets are also J55 specific because of the increased diameter. Looking at my J55 fronts, I can't imagine that a caliper sitting 1/2" closer to the hub would work:
especially after looking at that picture. Interestingly enough according to a little research RPO J55 was a 12.9in front rotor ...same as the 95 Standard...but they offered a J55 option on the '95 also ...so I wonder what the difference was. The '94 (Standard) was 11.9 Front and rear..the '95 (Standard) went to a 12.9 front and 11.9 rear.
Le Mans Master
Joined: Sep 2003
Posts: 5,874
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From: Littleton CO
Originally Posted by DFWLCJ
Interestingly enough according to a little research RPO J55 was a 12.9in front rotor ...same as the 95 Standard...but they offered a J55 option on the '95 also ...so I wonder what the difference was. The '94 (Standard) was 11.9 Front and rear..the '95 (Standard) went to a 12.9 front and 11.9 rear.
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Le Mans Master
Joined: Jan 2004
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From: Why are there squished peanut butter cups in my underware?
Originally Posted by DFWLCJ
Unless something has been done to them the '94 spec was for 11.9 In Disc front and rear....changed in '95 to larger front.
For 1994, only the ZR-1s and Z-07s received the J55 13" HD brakes from the factory. All other `94 Vettes are base FE1 suspensions with the 12" brakes.
As said, a previous owner could have changed them.
Originally Posted by *89x2*
...the gospel has been spoken 
