1996 Chevrolet Cavalier:
Brakes Lock Up Rear Tire when Applied

Question:

I have a 1996 Chevrolet Cavalier with 127,000 miles on it. I recently replaced the front and rear brakes because my rear tire would lock up when braking. I believed that I needed new brakes or needed to turn them.

After a close inspection I really didn't need to replace anything, but I did anyway and everything looked to be fine. After a few days the problem had not repeated itself, but then it eventually came back.

That happened last winter, and since the weather has warmed up the rear brakes have not done it. But I had one friend watch my car when the brakes locked up and he said that the rear right tire locks up and then it pulls down that side of the car. I also noticed that the problem goes away when I get my car over 20 mph for 10 to 20 seconds. I have ABS. God bless, SAM

Answer:

Your Cavalier uses drum brakes in the rear. Look them over one more time to be sure we're not missing anything. There are primary and secondary brake shoes. The primary is the smaller brake shoe which is mounted toward the front of the vehicle. Reverse installation of the shoes can cause uneven brake application at the rear wheels.

You also have to eliminate improper hardware installation, possibly a binding wheel cylinder, obstructed brake hose or line, too thin or a cracked drum, or contamination of the brake linings as being a cause to the lockup.

And then there's the other end of the hydraulic system. Hydraulic brake pressure is controlled not only by the master cylinder when you hit the brake pedal, but also by a proportioning valve, a metering valve, or combination of both. These valves are calibrated to adjust brake pressure, front to rear, in order to provide equalized and efficient braking. About 60 percent of braking comes from the front and 40 percent from the rear. There are also "split" systems which apply brake pressure at the left front and right rear wheel, separately from the right front and left rear.

A problem there could also lock up one rear wheel prematurely. There have been issues with rear drums locking up while sitting for long periods of time in the winter due to ice build-up, but it's usually locked from a stop and comes free as the ice thaws. This problem is preventable with the installation of updated rear backing plates.

There have also been cases of brake drag from binding parking brake cables causing brake overheat and related symptoms, including a possible lockup at a rear wheel. An antilock brake problem, although not common to a lockup condition, is also possible. If you can't figure it out, have your brakes professionally inspected before it leads to a hazardous situation on the road.

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