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Engine Braking
bonnie_rick
Member Posts: 115
the News and Views Conference's Engine Breaking:
Good or Bad? (Topic #206).
Check out the beginning and come right back here
to continue the discussion!
Bonnie Rick
Town Hall Community Manager, edmunds.com
Good or Bad? (Topic #206).
Check out the beginning and come right back here
to continue the discussion!
Bonnie Rick
Town Hall Community Manager, edmunds.com
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Comments
You're right, but those aren't the only 2 choices.
When you're doing 60 and a light up ahead turns yellow then red, you just lift off the gas and apply the brakes. Downshifting (at this point) is wrong and disengaging the clutch or putting the trans in neutral are wrong.
When the vehicle's speed has reduced a lot, there comes a time when you have to disengage the clutch or you'll eventually stall the engine. At that point, if the light has changed, you can double-clutch, select a new gear and re-engage the clutch. If the light hasn't changed, and you're going to have to come to a dead stop, continue using the brakes with the clutch disengaged.
You're also right that you have to downshift on turns, but you do it (as on straights) when you need the lower gear in order to accelerate, not before that. Again - you don't want to engage the lower gear to reduce your speed, but to accelerate. Your brakes (with the clutch engaged and with the trans still in the higher gear) are the tool to use for decelerating.
First of all, if you're happy and comfortable with the way you're driving now, there's no reason to change it unless you want to. You could play with new techniques if, like me, you find it kind of interesting.
It's true that double-clutching was necessary once, and that it's optional now. It still puts less strain on the parts though, and makes your synchros last longer, and it's fun, if you're into that sort of thing. It's harder on some cars than others, on account of the arrangement of the pedals.
If you don't double-clutch, you'll definitely want to at least blip the throttle before you re-engage the clutch, to match the engine revs to those of the trans.
I think that postponing downshifting till it's necessary is easier and simpler than any other way. You just pretend it's an automatic - brake to slow the car down without ever thinking about the clutch. Not until you're either: a. going pretty slow, or b. need to accelerate, do you need to downshift. If you didn't slow a lot and you're engine's pretty flexible, you still might not need to downshift. My engine's weak at low revs but my car is light, so I'll usually go ahead and roll on the throttle to re-accelerate, unless I have a need to regain speed quickly.
Recently I started playing around with the toe-and-heel method. I can tell I need lots of practice modulating the brake with my heel. But I can also see how it could be useful on a sporting occasion.
I agree with those who cite the desirability of being in an appropriate gear but I don't agree that this requires downshifting through each gear. My personal preference is to plan ahead, leave the car in 5th (or whatever depending on speed) and select an appropriate gear a second or two before the transission from breaking to power (Which should be at or before the apex if you want an optimum exit speed.)
Just my opinion, but I'm always right and I never lie.
People with different cars and different foot sizes do it slightly differently. I tend to slide my right foot over closer to the accelerator, keeping the "ball" of my foot on the brake pedal. I apply a steady pressure on the brake pedal for braking and swing my kneel to the right to blip the throttle with the edge of my shoe. I find it a lot easier to modulate braking this way, rather than the traditional toe-and-heel movement.
When I learned to drive, I was never told to downshift 4-3-2(only to 1 when stopped) in the 60mph stop light example from above.
However after driving my 318i for a couple of months I experimented with it. I drive very aggressively (only towards the road not other drivers) and wanted to experiment. I am convinced this is how to drive.
When I drive my automatic 735i with the steptronic to sport mode, and after the car is used to my driving style, I notice something. The instant I take my foot of the gas the car downshifts as it can tell something is up, either a stop or corner. Now why would the car do this? I think it's because it know's I will not be accelerating anytime soon, and is slowing the car before I apply the brakes. This is always right for me, thank god for BMW's.
Anyway when in a stick, thank god for sticks too, I shift down to slow down with my brakes. Now am I wrong here but how can it hurt the trans if you match revs to downshift? It's the exact reverse of an upshift under power. I think it's fine and my car runs like a beauty and I am sometimes right.
If you're manually rev matching on your downshift, then there should be no transmission wear. However, for those of us who usually rely on the transmission synchros to rev match, we need to be careful.
Why do you mention automatic? Does is has anything to do with timing belt? I mean, whether timing belt will last longer on automatic cars or what?
(I'm sure I will get a lot of responses on that)
If I drove a V6 or V8, sure, I would use automatic, but with a 4cyl, I need a stick.
I like the 4cyl for economy, and the stick to get the most performance from the 4cyl.
Sugardog.
THE PROPER WAY TO SLOW DOWN AND STOP
(Manual Transmission)
1. Apply the brake.
2. When you feel the engine about to stall, downshift.
3. Continue applying the brake. Repeat #2 as necessary.
4. Only when you're just about to stop, at which point you should be in second gear, disengage the clutch.
With this technique you are always in gear, but the work of stopping the car is on the brakes.
IMPROPER WAY TO SLOW DOWN OR STOP #1
1. Disengage the clutch.
2. Either keep the clutch disengaged or put the car in Neutral.
3. Use the brakes to slow down or stop.
This technique is dangerous because you are freewheeling, and in case you need to get moving again you are a) not in the correct gear and b) your engine's revs will not match the gear you need to be in.
IMPROPER WAY TO SLOW DOWN #2
1. Without braking, downshift.
This technique is bad because it shocks and stresses parts of your car that shouldn't be shocked and stressed that way.
PROPER WAY TO GO DOWN A LONG GRADE
1. Select a low gear.
2. If necessary, use your brakes to control your speed.
You're sharing the work of slowing the car down between the engine and the brakes.
IMPROPER WAY TO GO DOWN A LONG GRADE
1. Disengage the clutch or put the car in Neutral.
2. Ride your brakes all the way.
The brakes will lose effectiveness and you won't be in the proper gear for your speed.
Feedback?
I'd make only this small adjustment to the first category:
(Assuming a non-panic stop)
1. Lift throttle. Compression braking will slow you.
2. Skip the downshifting unless you're planning to accelerate again. If you're slowing to a stop, apply brakes gently until *just before* the engine tends to bog.
3. Shift to neutral, continue braking.
If it's a hard-braking stuation, get on the brakes and use as much of them as necessary. That's what you've been saving them for.
I hope to do some driving schools before too long.