Brake heat-can timeing of braking affect heat?


#1

Ignoring safty concerns about reckless driving here, what type of braking would lessin the amount of heat buildup in your brakes?

I have three types of braking in one type of situation (downhill straight, no turns, must stop at the bottom of the hill)

1) dragging brakes continusly down the hill to keep speed at a consistant 35-40 mph



2) applying brakes as needed (to keep the car between appx 25-55 mph) down hill.



3) waitng until last point and heavily appling brakes (not locking) to come to dead stop.



Just a little curiousity.


#2

I’d say all three present a problem:

-If you ride the brakes all the way down, it will heat them and they will probably fade. You may not be able to stop when you get to the bottom.

-Hitting the brakes occasionally is a little better, but will still heat the brakes and possibly lead to fading.

-If you wait until you get to the bottom, letting your speed increase, the situation at the bottom becomes more like a panic stop. Your brakes may handle it just fine, but not the greatest way to deal with it in my opinion, especially if the road is wet or there is traffic.

In all three situations, the brakes will be dissipating around the same amount of energy (quite a lot), and you will wear the pads and possibly glaze them, as well as risk warping the rotors if you get them hot enough. This can lead to reduced braking performance and/or an annoying pulsation when you hit the brakes that only resurfacing or replacing the rotors will fix.

If it’s a long hill, you should probably downshift and let the engine do some of the braking, using the brakes sparingly to keep your speed reasonable for conditions until you reach the bottom, then come to a ‘normal’ stop. But out of your three scenarios, I’d say number 2 is the best, because it allows your brakes to cool somewhat between applications.


#3

IMHO, number 2 is best.

Use the brakes as you need them to control speed. That’s what they’re designed to do. You won’t hurt the brakes regardless of your technique.


#4

#2 will result in the least wear and tear on everything…


#5

You obviously don’t live in the mountains.


#6

As long as you are not locking the wheels, they all mean that you will be transferring about the same energy to the brakes heating them up the same amount and causing the same amount of wear. If you lock your brakes they will save the brakes, but cost you in tires.

The amount of energy (heat) is the same. As inferred however, the far more important issue is safety and should be everyone’s first concern.

From the view of fuel usage, using the brakes as little as possible (take your foot off the accelerator early) is the best bet.

#7

#2 and #3 will dissipate more of the energy with wind resistance instead of in the brakes.

I vote for #2 with engine braking.


#8

I choose NONE OF THE ABOVE. For a steep down hill ride that builds up that much speed, you need to learn how to use the engine to help control downhill speed. You can downshift the engine and let the resistance of the engine keep you from building up speed. This does not harm the engine or transmission in any way, and saves the brakes for when you need to stop.

#1- NEVER DO, especially on a long down-grade. If you need to hold the brake consistently to maintain a speed, the brakes will built heat continuously until they fade, and you have no brakes, even after allowing for cool down. You really need to learn to downshift and let the engine help hold the speed.

#2- Try never to do consistently. Short down grades may be OK, but not for long down grades. If you learn how to downshift and allow engine braking to control your downhill speed, having to use the brakes to control the speed will only be a rare occurrence, like running up behind someone going slower or approaching a sharp turn. The brakes should do fine under these conditions as long as you use the engine to control your speed.

#3) This is how the brakes were designed to be used. The heat built-up will be quick, but the rotors are designed to dissipate this heat more effectively than a constant, sustained application of heat, like riding the brakes. When used with engine braking, this application will not be so extreme.


#9

#2 is best. I believe to be known as "stabbing it allows your brakes to cool between between use. Constant pressure is a very bad idea on a downhill run…brakes can overheat which can lead to no braking ability


#10

I’d go with No. 1. At likely a higher average speed than 25-55 mph, vehicle wind resistance will be helping the brakes to slow the vehicle. Applied brakes still have most of the rotor surface exposed to air for cooling. The rotors will be spinning faster at 45 mph at which also will be moving air past the rotors at a likely higher average speed than 25-55 mph.

For anticipated stoplights, I brake long and easy and get great brake pad life typically 70,000 miles to the first pad change on GM cars and we do much of our driving in an urban area with, of course, plenty of stoplights.

No. 1, however, is not easy to think of as being more gentle on the brakes.