Which B-bodies have 12" brakes


I found 3 B-body wagons in the bone yard that seem to have the big brakes, but I want to be sure. The rotors measure about 11-5/8" to 11-3/4". Are these the right ones, or is this what the 11 inch rotors measure out to ? I didn't want to go through all the work of removing them & wasting the cash to find out they were the wrong units. I also took the "Service Parts Identification" decals off of all 3 to check codes. After comparing all the codes, I found they all have JA2 which lists in the code description as "Brake, Heavy Duty Disc Drum" . Is this the correct code for the 12 inch brake option ? I read that all the wagons have it, but is this true ?

Please could someone that knows, chime in !

Much appreciated !!

And the 11" have the 5 on 4-3/4" ??

What size wheel studs are used...12" are 1/2" and 11" are 7/16" ??

Have the bone yard torch them off for you. I gave the yard guy an extra $5 to cut the old ball joints and tie rod end off for me.
Tarey D.
GN ERGY, I wasn't refering to the wheel lug nut sizes, I was just trying to make sure I get the right parts. I have no problem doing the work to remove them as this place doesn't do it. I figured if the 12" rotors had the 5" circle, then the 11" may use the 4-3/4". I was just using the stud diameters (and bolt circle)to help me identify the 12" spindles, in relation to the 11".

Thanks again for the help
I'm pretty sure all studs for either size rotor are the same. What are you gonna do for wheels if you have 5" bolt pattern? Have different on front and rear?
All B-body wagons have the 12" rotors as standard. The bolt pattern is 5 X 5" with 1/2" studs. The 11" rotors(on the sedans) can be either 5 X5" or 5 X 4.75", again the 5" will have 1/2" studs and the 4.75" will have 7/16" but only some real oddball models have the 5 X 5" pattern. You are going to have to use the 1LE Camaro rotors for the 12" upgrade. The 12" rotors actually measure out at 11.75 to 11.875.