My car has a hard brake and a long stopping distance and I believe the power booster is causing the brake problem. What brake parts on the car are causing the power booster to go bad?

Asked by goodcause Jul 30, 2013 at 08:23 PM about the AMC Concord

Question type: Maintenance & Repair

The rear brake hoses are old and could be causing the brake problem. The rear brake shoes could be dragging on the drums. I've replaced the master cylinder twice, new drums, new rear wheel cylinders, new front wheel rotors, new inner and outer wheel bearings, pads, shoes, new front brake hoses, and replaced the front bare calipers with loaded ones on the front disc brakes. The brake problem is still there. One wheel is hard to move on the lift. The proportioning valve has not been replaced. There could be some restriction in the line causing the front brake pad to intermittently grab the front rotor causing drag on the front wheel. The service manual says there might be an internal malfunction in the power brake unit that’s causing the hard brake. The power brake unit could be binding internally. If there's an inbalance on the wheels on either side, the new power booster will soon go bad. Please help me.

1 Answer


It seems a little odd that you didn't replace the brake master cylinder and booster as an assembly, most hard braking is cause by a failure in the booster, make sure that the vacuum booster has a good vacuum supply and not leaking back via the check valve as that will also cause a hard brake.

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