Brake fade under heavy braking

[Talek]

I was driving home tonight, and got on the throttle a bit for fun but the light ahead of me turned red, so I had to stop pretty quickly. I hit the brakes and they gripped well at the start, but then they felt like they were slipping and I ended up drifting partway into the intersection. It wasn't fun. I was told that I had new brake pads put on when I bought the car, a little over a year ago, and my brakes are still responsive during normal every day driving.

Anyone know what it could be? I'd like to get it taken care of before winter really hits. Thanks!

 

[steve]

There is a huge difference in how various pads perform. You at least should have the larger dual piston calipers stock on your car so getting a performance brake pad like some Hawk or Porterfields should sold that problem. Make sure that your brake fluid has been flushed in the last year or so. DOT 3 brake fluid absorbs water and lowers the boiling point reducing your braking ability and over time ruining the brake lines and calipers.

Steve

 

[Defiant]

I was driving home tonight, and got on the throttle a bit for fun but the light ahead of me turned red, so I had to stop pretty quickly.

Well, we need a bit more than that. What's your idea of "a bit of fun"? When Road & Track tested the '95 2G (which had a bit better brakes than the 1G), the distances went from 125 at 60mph to 225 at 80mph -almost double. That was with guys who test brakes regularly, and are used to it. Getting yourself used to it will eat up a set of street brakes, and that's in no way meant to be a slam on how well you drive.

I hit the brakes and they gripped well at the start, but then they felt like they were slipping and I ended up drifting partway into the intersection.

Brakes work by transferring the kinetic energy of rolling down the road into heat, which the pads and disks must soak up and dissipate into the surrounding air (see Heat Transfer). When they've absorbed as much heat as they can get rid of, braking force diminishes greatly (brake fade). No, you don't boil the fluid for quite a while after that, and it's a safe bet that not ten people reading this have ever boiled their brake fluid- when that happens, you have no brakes at all, and the pedal hits the floor. Hard.

It wasn't fun.

No, it's not. It's scary as hell. Real fun, real scary was the sensation of putting nice American Libra wheels on your 510 or 240Z and making the first stop in the rain,and finding out your braking capability hadn't been affected, because you can't affect something that's just not there. Turns out Datsun brakes didn't much like getting wet, and that it takes about fifty feet to get them to start working again.

I was told that I had new brake pads put on when I bought the car, a little over a year ago, and my brakes are still responsive during normal every day driving.

Sounds like less-expensive pads. Nothing wrong with them for normal use (they're often better at speeds up to about 30mph), but take a good run over a decent (3000' +) hill and you might find they're toasted. Nevermind the racey-boy superpads, just the Premium pads from GrandPepKragenSchuckNAPAZone will be a huge improvement.

Anyone know what it could be? I'd like to get it taken care of before winter really hits. Thanks!

One other thing: if you have ABS, use it. Yes, Andretti can out-brake ABS, but unless you make your living cooking brakes for a car magazine, you and I probably can't. When something even might be going wrong in front of you, mash the living shit out of the brake pedal and make the ABS go to work, and don't let up on that pedal until you're stopped.

Oh, make sure there's not someone close behind you.

And, uh.... most of the lights around here turn yellow before going to red... (that was a bit of a slam, and I apologize).

 

[Talek]

Ok, I'll be a bit more specific. I was going about 60mph and proceeded to begin braking about a block away when I saw the light turn yellow and knew that I wouldn't make it through the light before it turned red.

I didn't slam the brakes, but pressed firmly and they slowed me down rapidly to about 20mph where they really started losing grip. By the time I stopped they were hardly slowing me down much at all.

The last time I had to stop quickly I had to slam on the brakes (because someone cut me off, not because I was speeding this time hah), and my ABS kicked in properly and my car stopped very fast. Since then though I have noticed a little bit of brake loss under heavier braking but this was the first time since I had to slow down quickly.