This is in regards to the '89 IROC in the sig...

I posted back here a few weeks ago with some pictures of my rear rotors. Basically, I had new rear rotors and pads, but the rotors had rusted because of rain (which is to be expected). What I did not expect was for much of the rust to still be there after weeks of driving--especially on the inner-most portion of the rotor contact surfaces.

Trying to fix this problem, I ended up rebuilding the rear calipers (PBR calipers). I rebuilt them both with AC Delco kits. After I rebuilt them, I didn't really notice any difference in the braking power. And the rear rotors are still rusted in the same regions. Plus, if I have the emergency brake engaged with the transmission in gear and the engine idling, the car still moves.

Under normal driving conditions, the car stops fine, but it seems like I have to shove the brake pedal in more than I should have to--like halfway in. And, once the car is stopped, I can still push in the brake a lot.

I have bled the brakes at all tires. I don't know if I'm dealing with an issue with just the rear brakes not working or what. But these brakes are definately not what I thought they would be. I come from driving an '88 Camaro SC (see sig) with rear drums, and the brakes on that car feel much better than on my IROC. I thought 4-disc brakes were supposed to stop better.

Any ideas as to what I should be checking?

Thanks

 

This is a much heated topic. There is another posting on here about the proportioning valve mod. It has to do w/ this problem. Basically, w/ a disc set-up, GM didn't change the proportioning valve, and the rear brakes do not have enough pressure. Think of it this way, how much fluid would it take to fill a wheel cylinder vs. how much it would take to fill the back side of a caliper piston. There are a lot of different fixes, the best probably being to put a plug in the front of the prop. vavle, (rear brakes) and install an aftermarket in-line prop. vavle. I personally have 3 small machinist washers behind the spring in my proprtioning vavle.

later, justin...

 

i to have this prob on my 89 iroc with 9 bolt and pbr disks, but it does not rust up, they just dont work, i think the pads are glazed because if the e brake is pulled all the way it is only about half way up. make sure your pads are not glazed and the e brake is adjusted right.

keep us posted.

thanks
anthony