I just got an '89 IROC-Z L98. I'm going to be taking the wheels off tomorrow to look at the brakes since they're making some goofy sounds in the back. I was looking at the rotors through the rims, and had to step back and ask "WTF?" The rear discs look almost like 12" (or about 11.75" due to my search results). Well the front rotors are much smaller than that. They look like they're about 9" or 10". Is that the way it's supposed to be?

 

Yup, the rear are aluminum PBR calipers and 12 inch discs and the front are 1 piston cast iron 10.9 inch rotor I believe

 

Cool... at least I know I'm not smoking crack!

Here's another question. I've been searching on how to repair my e-brake. I haven't been under the car enough to see if the cable is moving, but the e-brake doesn't work. It's got the PBR rears, and from my TGO search results, all I see is a garbled bunch of crap about people having to buy new calipers to fix everything. Is that what I'm going to have to do? My passenger rear brake makes some noise every now and again, usually when I'm in reverse. I'm going to be inspecting closer tomorrow, but just what am I getting into here?

edit: The brake light is on, there's excessive pedal travel, the pedal is 'mushy'. What order should I troubleshoot? Master Cylinder, Proportioning Valve, Lines, Calipers?

 

if the brake light is on, you may have a leak somewhere. check the entire brake system for leaks. could be a bad hose, leaking caliper, or even master cylinder.

 

They are 11.655 dia rotors with PBR Aluminum single piston calipers. These were the J65 rear disc option required on the BW 9-bolt rear. The best rear disc's on the 3rd gen car are 1989 ones.

 

Well you guys wouldn't believe how the troubleshoot process went! lol I noticed some seepage from the master cylinder seals. I thought "cool, at least I know what's going on here!" So, I put some more brake fluid in the cylinder. I pressed on the brakes just to see if it makes a difference after adding the fluid. Well guess what comes running out from above the rear axle? Yup, a nice steady stream of brake fluid. So, under the car I go, and to Summit I call. Earl's stainless lines on the way! I think I have to look at this in the "glass is half-full" frame of mind or I think I'd be really pissed! lol

 

Actually in the front all third gen camaros came with 10.5" rotors stock. You've got an 89' IROC so you've got 11.65" rotors in back.

 

I have a trans am GTA, also, '89. Are the brakes the same? the rear look 12, fronts 10... im wondering because i know they didnt always do the same for camaro as they did for 'birds and visa-versa

 

Same 9-bolt rear with the PBR 11.655 dia brakes used on both Firebirds & Camaros in 1989.

 

Any reason why the rear-disks are actually bigger than the fronts?

What diameter are the rotors on a 1LE car?