I drive a small automatic car. For the most part, it struggles a bit with steep uphills, and picks up speed when going downhill. That’s to be expected.
But then I noticed some downhills actually slow it down. I’ve noticed during a two-hour motorway trip I often do to visit family, there are some specific downhills, not all, just some, where my car always slows down and I have no idea why.
Ideas?
engine braking ?
This is very likely the reason. Not all downhills will induce it, but the automatic is down-shifting to slow your acceleration. There are various ways for your car to know but manufacturers want the driver in control, not the environment. Depending on the car and speed you may not hear it, but when it slows down does it sound like the engine is revving higher?
It also helps keep brakes cool, important for mountain driving.
One of my cars hardly does any automatic engine braking. My other vehicle will keep or decrease speed down long hills/mountains. No noticeable change in engine noise at all. Makes long trips through the mountains much easier, especially because it’s a heavy vehicle and overheated brakes is a very real concern.
What happens when the brakes get too hot? Do they gently stop working or can they just explode or something?
Generally much less effectiveness to almost none as they get hotter
Source: was an idiot teenager
Can you continue using them once they cool back down, or does the heating cause permanent damage?
At some point it probably does. And can probably catch fire. Mine were fine once they cooled
Thanks for the reply.
I was wondering if safety was like motorcycle helmets - I read that if you dropped them, like say, you kept them on the seat of your motorcycle and it fell off onto the ground, it’s no longer safe for use and needs to be replaced.
Brakes are assholes, when they overheat they can fail basically suddenly. You do get a warning in lower effectiveness or one side braking more than the other, but if you’re not familiar with that feeling, you may not realise it. Also modern cars are made so that everything just feels the same all the time.
You can see it in car races such as in F1. Braking braking, suddenly boom, car is in the barrier.
Yes, they’ll work again after cooling down unless they’re shit and got deformed, or you crashed.
That’s why it’s important to have brakes checked regularly, you get little to no warning in modern cars. Same with clutch and a bunch of other mechanisms.
No, it doesn’t make a different sound when slowing downhill like this.
Depending on the car it may be so quit you can’t. The only other way to know if it’s down-shifting would be to check the RPM gauge when the cars slows on downhills - it should jump up ~few thousand RPM (or kilometers depending on where you live).
Okay, many are answering this. But why is it only on some slopes, not all? Why this isn’t happening for most?