Do you heel-toe on the street?

[LeVeL]

I'll agree with the feeling of control but in terms of actual braking distances, I don't think downshifting plays a role. Personally, I only find downshifting on the street to be useful when I have to brake hard (and don't have time to do the regular rev-match downshift while letting off the brake) but not to a stop, meaning that I have to brake hard but then accelerate again.

 

[mpicco]

Imagine going downhill, and you need to brake, you're going 80, and need to safely slow down to 30... if you just press the brakes, and the clutch, gravity suddenly is accelerating you more than if you were braking and correctly downshifting. And then at the end you're at the correct gear, lets say 2nd, which would prevent you from accelerating away cos of the gradient. That's all I meant.

That's another horrible piece of trying to explain. English is my 3rd language. Over and out.

 

[prizrak]

Imagine going downhill, and you need to brake, you're going 80, and need to safely slow down to 30... if you just press the brakes, and the clutch, gravity suddenly is accelerating you more than if you were braking and correctly downshifting. And then at the end you're at the correct gear, lets say 2nd, which would prevent you from accelerating away cos of the gradient. That's all I meant.

That's another horrible piece of trying to explain. English is my 3rd language. Over and out.

I see what you are saying but either it's a language barrier issue or you are misunderstanding what the rest of us are saying. No matter what gear you are in, no matter if the clutch is engaged the brakes will always slow your car down much faster than any kind of engine drag. There is no additional braking force given to you by your engine when you are hitting the brakes because the amount of force involved is that much greater. Essentially think of it this way, if you are accelerating using engine power and then suddenly you turn on a rocket booster causing you to have massive acceleration. Even if you let off the gas the rate of acceleration will remain constant because the amount of force accelerating you from the booster is much greater than anything the engine could ever put out.

If you are just trying to get into the right gear as soon as possible then what you are saying makes sense but it's not really related to hills, same would apply for something like a highway off-ramp as well where you are going from 60 to 30.

 

[Hbriz]

I don't think he's talking about emergency braking though. Just coming to a gentle stop. And in that case it may be that the engine braking does have a bigger effect on slowing the car (compared to if you're braking hard).

Put it this way, if you're going down a hill at 80km/h with the clutch in, you're going to have to brake much harder to slow the car down in a given distance than if you downshifted to third and then to second etc... Not emergency braking but just slowing down gently.

 

[mpicco]

Yes, with applied brakes too, enough to slow down as much as you need but not screeching down the hill in tyre smoke and glowing pads.
Then at the bottom or when you're done braking, you're at the correct gear to set off again, instead of being bogged down still in 5th.

 

[equiraptor]

Put it this way, if you're going down a hill at 80km/h with the clutch in, you're going to have to brake much harder to slow the car down in a given distance than if you downshifted to third and then to second etc... Not emergency braking but just slowing down gently.

I think part of the misunderstanding is that it appears, to at least me, that the claim is one should keep the brakes applied gently and downshift while going down the hill. This is not the correct behavior - it's a great way to overheat the brakes. Rather, downshift to help control acceleration, and then brake strongly as needed to scrub any gained speed. While the brakes are applied, in behavior like this, the percentage of slowing force coming from downshifting is minimal. Overall, the slowing (or reduced acceleration) from downshifting is significant.

If we're just talking about one brief hill, it's not very significant. But if we're talking about coming down off of a mountain, keeping the brakes cool can become rather important.

 

[Hbriz]

My main experience with something like this is a mountain that I have to drive down to get into the city where I live. At peak hour, traffic is bumper to bumper. Braking strongly would be a sure way to get someone up your rear bumper. For most of the descent my car will hold the speed limit in 4th, but occasionally I will have to use the brakes. Only occasionally though. The amount of people I see just riding their brakes all the way down without any form of engine braking is probably close to half of the cars on there.

At the bottom of the mountain I have to take an exit and slow down pretty quick. To do that I will downshift and brake gently, as braking hard will just end up with the person with overheating brakes who was riding my bumper the whole way down ploughing straight into me.

 

[mpicco]

I think part of the misunderstanding is that it appears, to at least me, that the claim is one should keep the brakes applied gently and downshift while going down the hill. This is not the correct behavior - it's a great way to overheat the brakes. Rather, downshift to help control acceleration, and then brake strongly as needed to scrub any gained speed. While the brakes are applied, in behavior like this, the percentage of slowing force coming from downshifting is minimal. Overall, the slowing (or reduced acceleration) from downshifting is significant.

If we're just talking about one brief hill, it's not very significant. But if we're talking about coming down off of a mountain, keeping the brakes cool can become rather important.

Sure if you wanna have everyone inside your car puking and screaming.
If you have to apply the brakes cos the gradient is so steep it's accelerating you then you're in too high of a gear. And then is when I'd heel and toe to a lower one. That's all.

 

[equiraptor]

If you have to apply the brakes cos the gradient is so steep it's accelerating you then you're in too high of a gear. And then is when I'd heel and toe to a lower one. That's all.

That's not always the case. Some roads are steep enough and some cars have little enough engine braking that the car will accelerate regardless of gear choice. These are the roads I'm thinking of when I'm talking about "strong braking". Doing this braking smoothly and with intention doesn't seem to cause any problems for anyone else, either in the car or others on the road.

As a clarification, when I say "strong braking" I don't mean "threshold braking" or maximum braking. I mean firm brake pressure instead of a small amount of brake pressure. The thought in my mind for "strong braking" is similar to the braking used to slow for a turn on the street. I'm also not saying it's necessary to brake strongly in all situations, but rather that braking periods should be relatively brief. If it's not possible to control speed with downshifting and brief light braking, it's better to brake more strongly than to brake for a longer time period.

 

[Spectre]

To add to that and to be even more specific, there are vehicles that have no significant engine braking, such as diesels without a compression or exhaust brake. If you wait for engine braking to slow my truck down, for example, you are going to be waiting a long, long, long time. It does eventually slow down without using the brakes, but that's due to driveline and wheel friction and can be several minutes after you let off the pedal. Even shifting down to first isn't going to help slow that thing down a hill because like most diesels that aren't in heavy trucks, I don't have a compression release brake or an exhaust brake. Long series of hills can be... interesting.

There are also some automatics out there that decouple the engine from the output shaft when you let off the throttle in the name of better fuel economy. No engine braking there either.

So much for 'you're not in a low enough gear.'

 

[M_Bolc]

I loved making the 500 plead for forgiveness and revving its nuts off either coming to a stop or approaching a corner.