Hello there, I am new to this forum and this is my first post! Anyways, this generally only happens when the car/brakes are cold (hasn't been driven for a few hours) The main problem is that when i begin to depress the brake, the car slowly comes to a stop like normal, then once I get to a certain point (I'd say about 30% depressed) it jolts forward very hard, like the brake have been slammed. As i continue to drive, it slowly dissipates..but it is VERY annoying for the first 20mins of every drive! I talked to the dealer and they just wrote it off as braking habits, but I am not doing anything out of the ordinary. Wanted to see if this is a common occurrence in the brakes on the Prius? Could it be the pads, rotors, brake fluid/line issue? Any suggestions!? Any help would be greatly appreciated!
Since your car has low miles, my guess is that the friction brakes are lightly used and may be contaminated with dirt. That might cause them to grab until they warm up. You can try cleaning the brake surfaces by speeding up to 45-50 mph, then shift to N and brake to bring the car to a stop. Repeat a few times. That might clean off the braking surfaces enough so that your problem will go away. If not, and you are up to a DIY project, I suggest getting a can of brake parts cleaner, then raising the car on four jackstands, removing the four tires, and pulling off the rear brake drums. Clean the rear brake shoes & drums, as well as the front pads & rotors. If you notice significant corrosion on the drums or the disks, this might be the cause of your problem.
It's just rotor/drum rust. Clean it in N as Patrick says, making sure to exert very slow, even pressure, and it should clear right up. . _H*
