Could driving on the autobahn cause Frank's brakes to misbehave?

Dear Car Talk

Dear Car Talk | Jan 01, 2005

Dear Tom and Ray:

I live in Germany, and I love your show. I have a 1995 Buick Skylark with 120,000 miles on it. I often drive 80 to 90 mph on the Autobahn. I find I must change my front brakes (and often my rotors) about every four to six months. Why is this happening? Additionally, when I am coming to a stop and am not at a high speed -- like when I'm pulling into my driveway -- the brake pedal sometimes goes all the way to the floor, as if I have lost all braking power. I do not see any leaking brake fluid. I've had four mechanics check it out, and they tell me my brakes are fine, but I don't believe them. Any ideas about what is going on here? I really appreciate any words of wisdom you can give. Thanks! -- Frank

RAY: Well, there are several possibilities, Frank, but I'm going to guess that you have a bad power-brake booster. When you step on the brake pedal, you activate the booster. The booster uses the engine vacuum to amplify the force of your foot and make stopping easier.

TOM: The way the booster often fails is by not releasing the brakes all the way. So when you're driving around town and using your brakes a lot, your brakes are slowly being applied more and more, even though you don't know it.

RAY: It's as if you're driving with your brakes partially applied. As you can imagine, that wears out your brakes pretty quickly. Like every four to six months.

TOM: It can also explain why your pedal goes to the floor on occasion. When the brakes are in constant use, they eventually overheat. That can boil the brake fluid, and boiling fluid can't do its job, so the pedal sinks. Once the brakes and the fluid cool off (by the next time your drive the car), the brakes return to normal.

RAY: But this is definitely a problem you want to solve quickly, Frank. While you're cruising along at 80 or 90 mph on the open highway, there's not much call for the brakes. But if a giant weinerschnitzel suddenly fell off a truck in front of you and you needed to stop short, you could find yourself in very deep sauerkraut. Am I mixing my food metaphors here? Anyway, get it checked out right away, Frank.

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