Automatic transmission. Should I use an engine break (save the brakes and discs) or brake pedal (save the trans) on hills?
I am not talking coming down pikes peak long. Like maybe a quarter to half mile long.
Good question–depends on the car, how steep the hill is, speed limit, amount of traffic, etc. Can you fill in some of the details?
You mean, by coasting or shifting down with that automatic?
Brake pads are cheap. Transmissions not so much.
I usually turn the OD off on anything more than a mile. If it really steep then I might do D3 or D2 depending on the car.
I have once experienced something close to a brake failure on a downhill ride, was not my car and not sure if the brake fluid was up to date. But that one experience is stuck in my brain for life. This is one situation I don’t worry much about wear and tear on my car.
Many owners manuals wil tell you how and when to use the lower gears in an auto for engine braking.
Brakes are much cheaper than transmissions…But on a long downhill grade it can become a safety issue and downshifting is warranted.
A quarter to half mile is nothing to worry about. Use the brakes. They are designed to stand up to far more than that. I go down a two mile stretch fairly regularly during which speed can build up pretty fast. I only use the brakes for this stretch and have never overheated them or even warped the rotors. Coming down Pike’s Peak, on the other hand, can definitely overwork the brakes and warrant downshifting to control vehicle speed and prevent brake failure due to overheating.
“Brakes are cheaper then transmissions…” technically, but have you priced out brake jobs of late ? Especially over the life of the car, cumulative brake job costs could surpass one transmission replacement job. It’s seldom, change the pads and turn the rotors anymore. Transmissions are designed for engine braking. IMO, it’s no more wearing then down shifting for acceleration. Even gate shifters and gear changing modes encourage users to change gears frequently themselves. Generally, autos shift way more then many people would in driving a manual…use them. Everyone thinks the only time they shift is when the driver does it…the darn thing is shifting regularly in cities and hilly terrain.
The hills are less than a mile, and I can replace my own brakes rotors bleed etc. I’ve gotten into the habit of downshifting my automatic, but I think I will switch to pedaling the brakes.
Thanks.
On long and steep mountain roads, your owner’s manual will tell you to downshift to keep the brakes from OVERHEATING AND FADING. That’s different from a little extra wear on a hill less than a mile long. Unless the hilll was extremely steep I would not bother downshifting.
If you’re driving a Freightliner or a Kensworth truck that has an engine brake, then by all means, use it, but only where it is legal to do so. If you’re driving a car, use the brakes for stopping. That’s what they’re for.
If you’re driving down a long steep grade, and you find yourself using the brakes to control your speed, downshifting can help prevent your brakes from overheating, and if your brakes overheat, the results could be disastrous in many different ways. You brakes could fade, or become less effective, the brake fluid could boil, and if it comes out of the master cylinder, it could damage the paint job, or worst of all, you could lose your brakes and lose control of your car.
It does absolutely no harm to an automatic transmission to downshift it and use the engine’s compression to help you keep your speed down on a descent.
Using the brakes for a long descent can cause them to overheat if the descent os long enough, steep enough, and you’re “riding” them instead of giving them some cooling time, But used properly on a typical descent, they should be fine. Overheating was a far bigger problem in the days of drum brakes, because they can’t dissipate heat the way discs do.
Which is preferable depends on the individual vehicle and the hill. Down shift a Camaro or a Mustang that’s equipped awith a big motor and the compression will probably be more than sufficient to keep your speed down without touching your brakes. Downshift a 1999 Corolla and you’ll probably be using the brakes anyway.
Big rigs are equipped with “Jake Brakes” designed to allow the truck to keep its speed down using the engine. Slowing 60,000 pounds using only the brakes can creat a ton of heat. Jake Brakes also make windows rattle, so in many residential areas they’re banned.
“use engine or disc brakes” I know what I’m about to say is shocking to some but…hate to admit it…I use both regularly at same time.
I’m shocked! I thought I was the only one that did that!
Brakes…
Using engine wastes fuel.
I drive a manual most of the time, but the newer automatics all have torque converter lockup in high gear so the effect is the same. Most downhill driving I control my speed just by letting off the gas, down shifting is not necessary.
Where I can clearly see the bottom of the hill/mountain and the speed isn’t becoming too excessive, I let it pick up a little speed and stay in the high gear. I may use the brakes a little to control the speed if necessary.
On a long steep downhill, I will down shift one gear below the normal gear for that speed. On a highway, that means D3 on an automatic or 4th gear on a 5 speed. That is strictly for safety. Then I use the brakes as needed for any further speed control. While the brakes may work fine even without downshifting, there is the risk of overheating and brake fade/failure. When it comes to brakes, I think it is better to have them and not need them rather than need them and not have them. Because, if you need them and don’t have them, you might not ever need them again.
If you ask “should I use the engine and transmission to propel my car, or the brakes?” there are people who will tell you to use the brakes.
Just to take it to the extreme, you can work all day on a tractor on hills and never use the brakes. When electric motors become the norm or cvt s get strong enough, at least with awd , I feel the same will be true for cars. With each succeeding generation, automatic trans are engaging more and more in braking.