What's the right way to stop safely, if your brakes fail?

Dear Car Talk

Dear Car Talk | Sep 01, 2010

Dear Tom and Ray:

I just saw a few minutes of "Worst Case Scenario: Brakes Fail" on TV, and it seemed like they were suggesting the opposite of what I've always been told. Basically, the host was saying if you're going under 20 mph, then you should try to downshift or use the emergency brake. But if you're going over 20 mph, you shouldn't downshift, because it could cause the transmission to break off, and you'd lose control. Instead, he said you should try to generate friction by swerving, or running into guardrails or small bushes. He also said that if you're going over 20 mph, you should not use your emergency brake. In the show, he was driving (well, sliding and skidding) down several hills before finally driving through some mailboxes and bushes, and into a tree. What do you guys think of his advice? -- Matt


RAY: Well, I think he was negligent in failing to suggest that you sideswipe a few parked cars on the way to the tree. That would have been more fun!

TOM: Actually, these days it's very hard to lose all of your brakes. Cars have dual braking systems. So if you wanted to cut someone's brake line and cause him to drive over a cliff to his certain death, these days you'd have to cut more than one of his brake lines. And in the real world, without mischief involved, it's unlikely that both halves of the brake system would fail simultaneously.

RAY: Now, it may FEEL like you've lost your brakes, because you may have lost half of them. And when you have a 4,000-pound vehicle, half of your brakes makes a big difference. But the first piece of advice we'd give is to stand really hard on the brake pedal. Your car may have more braking power than you realize.

TOM: The next thing to do is downshift. It doesn't matter what speed you're traveling. If you have an automatic transmission, go right to the lowest gear. Modern transmissions are electronically regulated, and the computer won't allow the transmission to go into too low a gear. It'll drop to the lowest appropriate gear for your current speed -- which will help -- and then it will drop down again once you've slowed down some more.

RAY: So the transmission will not break off. But even if it does, what do you care? Your interest is in saving your life and those of other innocent people. A transmission can always be replaced.

TOM: Once you've downshifted, then I would advise you to apply the parking brake. You'll notice that carmakers no longer call it the "emergency brake." Their lawyers made them change the name, because it didn't always work in an emergency. But it might work, and it often will work, so you absolutely should give it a try, regardless of speed.

RAY: And then, if all of that fails, start looking for soft stuff to crash into. An unmanned roadside farmer's market is ideal, as lettuce has proven to be an excellent energy absorber. Good luck, Matt.

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