Posted By: 71X-mark
Power Disc Brake Stopping Power Inadequate - 09/07/11 02:02 AM
I know the stopping power of a power disc brake '71GTX is much better than what I'm experiencing with my car. In fact, it makes me nervous, but I can't seem to isolate the problem. Here are the specifics:
1. Restored Midland-Ross booster with lever assembly & short reinforcement plate(Booster Dewey).
2. Correct '71 power disc "snout nose" type remanufactured Master Cylinder (Cardone).
3. All new stainless brake lines, hoses and proportioning valve (Inline Tube).
4. New Rotors & rebuilt calipers.
5. New riveted semi-metallic disc pads, rear linings and wheel cylinders.
6. Intake Manifold vacuum at idle: 11"-13".
7. DOT4 brake fluid.
When applying the brakes, the pedal moves about an inch or two, but never to the floor, even when applying greater foot pressure. However, braking response remains inadequate. I can't say that I would consider the pedal feel as excessively spongy. My brother has the same car and I know he can lock the front brakes...mine never comes close to doing that.
I had the brakes checked for air in the lines and the rear brakes adjusted. Someone mentioned that the rotors may be glazed, but I took a peek at them and didn't notice anything unusual. There are no obvious leaks.
My research as to some possible causes are as follows:
1. 1971 Chrysler Chassis Service Manual shows power booster with lever assembly for 10" rear drum brakes (p5-27), and booster for 11" brakes (p5-28). I have the setup for 10" brakes, yet I have 11" rear drums.
2. Incorrect Booster Pin length (or needs adjustment). I don't have a clue on this one.
3. No residual valve in master cylinder for the rear drums. Don't know this one either.
I am hoping that someone could help me resolve this so that I can fully enjoy driving the car. Thanks for any input.
1. Restored Midland-Ross booster with lever assembly & short reinforcement plate(Booster Dewey).
2. Correct '71 power disc "snout nose" type remanufactured Master Cylinder (Cardone).
3. All new stainless brake lines, hoses and proportioning valve (Inline Tube).
4. New Rotors & rebuilt calipers.
5. New riveted semi-metallic disc pads, rear linings and wheel cylinders.
6. Intake Manifold vacuum at idle: 11"-13".
7. DOT4 brake fluid.
When applying the brakes, the pedal moves about an inch or two, but never to the floor, even when applying greater foot pressure. However, braking response remains inadequate. I can't say that I would consider the pedal feel as excessively spongy. My brother has the same car and I know he can lock the front brakes...mine never comes close to doing that.
I had the brakes checked for air in the lines and the rear brakes adjusted. Someone mentioned that the rotors may be glazed, but I took a peek at them and didn't notice anything unusual. There are no obvious leaks.
My research as to some possible causes are as follows:
1. 1971 Chrysler Chassis Service Manual shows power booster with lever assembly for 10" rear drum brakes (p5-27), and booster for 11" brakes (p5-28). I have the setup for 10" brakes, yet I have 11" rear drums.
2. Incorrect Booster Pin length (or needs adjustment). I don't have a clue on this one.
3. No residual valve in master cylinder for the rear drums. Don't know this one either.
I am hoping that someone could help me resolve this so that I can fully enjoy driving the car. Thanks for any input.