# transmission questions..



## ayn (Dec 19, 2001)

*Re: Re: Re: transmission questions..*



ALEX325i said:


> *
> 
> Hmmm... I use engine brake a lot. Granted, I rev the engine up accordingly before downshifting. This way downshifts are smooth AND the engine speed is compatible with the ground speed...
> 
> ...


you're right, if you rev-match and do it smoothly, no extra wear, as long as you're sure the lower gear can handle the speed you're going... i was thinking about slowing down the car at ~120mph when i posted, i don't think engine braking would be a good idea... but u'r right, at normal speeds if done smoothly should be no problem.

the step downshifts for us when in sport mode, and since there is a torque converter it's done pretty smoothly, so like you said, it's alright.

it's general consensus that brakes are for slowing down your car, and engine/tranny are for pushing it... go to any driving school and that's what you will hear... to get around a corner fast, you will have to brake, heel-toe downshift, and then you'll be at the turn out point in the right gear to accelerate...

--Andrew


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## Plaz (Dec 19, 2001)

From the manual... with a big "exclamation point" icon:

"Do not coast with the clutch depressed or with the transmission in neutral. Do not coast with the engine shut off. The engine provides no braking effect when the clutch is depressed and there is no power-assist for braking or steering when the engine is not running."


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## ff (Dec 19, 2001)

Plaz 330i said:


> *From the manual... with a big "exclamation point" icon:
> 
> "Do not coast with the clutch depressed or with the transmission in neutral. Do not coast with the engine shut off. The engine provides no braking effect when the clutch is depressed and there is no power-assist for braking or steering when the engine is not running." *


Why would someone want to coast with the engine shut off? hehehe "yep, I saved .000001 cents worth of gas by shuting the engine off as I cost to every stoplight."


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## ALEX325i (Dec 19, 2001)

*Re: Re: Re: Re: transmission questions..*



ayn said:


> *
> 
> it's general consensus that brakes are for slowing down your car, and engine/tranny are for pushing it... go to any driving school and that's what you will hear...
> 
> *


I know. I've been to a couple motorcycle performance riding schools and that's what they teach. However, that's one of those things they teach knowing that nobody's going to do it... Heck, one instructor even downshifted twice going into a corner 10 minutes after teaching that...


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## Plaz (Dec 19, 2001)

ff said:


> *
> 
> Why would someone want to coast with the engine shut off? hehehe "yep, I saved .000001 cents worth of gas by shuting the engine off as I cost to every stoplight." *


Agreed, but that was somewhat beside the point. I just didn't want to butcher the quote, and they had the two issues addressed together.

The point being that "proper" driving procedure per the manual, is, with a manual tranny, to always use engine braking, and never do any significant coasting in neutral or with the clutch depressed.


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## ayn (Dec 19, 2001)

*Re: Re: Re: Re: Re: transmission questions..*



ALEX325i said:


> *I know. I've been to a couple performance motorcycle riding schools and that's what they teach. However, that's one of those things they teach knowing that nobody's going to do it... Heck, one instructor even downshifted twice going into a corner 10 minutes after teaching that... *


there is a pretty significant difference in lap time with and without heel-toe downshift, but for non-race events, most people probably don't do it I guess... and unfortunately I got the Step so I can't even if I want to... 

I'm gonna get a house first, and then I'll get another car...

--Andrew


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## Dean325Ci (Jan 11, 2002)

All this talk about shifting is making me want to go out and drive!!:thumb:


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## ff (Dec 19, 2001)

Plaz 330i said:


> *
> 
> Agreed, but that was somewhat beside the point. I just didn't want to butcher the quote, and they had the two issues addressed together.
> 
> The point being that "proper" driving procedure per the manual, is, with a manual tranny, to always use engine braking, and never do any significant coasting in neutral or with the clutch depressed. *


I guess you could look at it that way too. I read it as meaning that you shouldn't coast when you should always be in a gear. I seem to remember something in driver's training about it being "illegal" (like anyone would police it) to coast down hills, etc with the car out of gear. I doubt it had anything to do with using the engine to provide braking assist as you come to a stop. More, that you had control of the car at all times.

I'm not saying that it bothers me that others use downshifting to slow a car. What I am saying that when you take the extra effort and wear on the driveline into consideration, it seems to make sense to just stick with the brakes. I can stop faster by concentrating on one thing, especially in emergency situations.


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## BS' Bimmer (Jan 30, 2002)

ff said:


> *
> 
> Once you consider the extra time and concentration it takes to use shifting as a means to slow down, I'm sure you'd find that stopping distances are mostly shorter when you only use the brakes.
> *


I don't find that it takes much more energy or thought to downshift to use the engine to slow me down. However, I think your post here really gets at the crux of the original post in this thread! You are 100% correct in saying that stopping distances are shorter using the brakes than using engine braking. This is exactly why driving schools teach you to use the brakes . . . you carry more speed farther into a corner, brake hard to drop speed to take corner, get on the gas in a hurry to exit! :thumb:

*leaves computer to go take a spirited drive* <silence> *BS' Bimmer returns much happier* 

That said, however, there are lots of situations where only a small drop in speed is needed (i.e., a quick corner, slowing slightly for a light that is changing soon, etc.). At these times, engine braking is just fine!


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## ff (Dec 19, 2001)

BS' Bimmer said:


> *
> That said, however, there are lots of situations where only a small drop in speed is needed (i.e., a quick corner, slowing slightly for a light that is changing soon, etc.). At these times, engine braking is just fine! *


I certainly agree!


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## Dan (Dec 27, 2001)

Plaz 330i said:


> *From the manual... with a big "exclamation point" icon:
> 
> "Do not coast with the clutch depressed or with the transmission in neutral. Do not coast with the engine shut off. The engine provides no braking effect when the clutch is depressed and there is no power-assist for braking or steering when the engine is not running." *


OK, I'll be the first to admit that I sometimes coast in neutral down certain hills. I have been doing this on selected roads for as long as I've been driving, and I see absolutely nothing wrong with it. For example, I will only coast in neutral on a very low or zero traffic road, where there are sufficient sight distances, not a steep grade, and it must be a road that I am familiar with. It is amazing how some cars will coast for a very long time without losing speed - the rolling resistance of cars in general has declined dramatically since the early 70's.


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## The HACK (Dec 19, 2001)

ff said:


> *If shifting gears doesn't cause ANY wear, then transmissions should never need to be replaced, right? I mean, my transmission and the neighbor's auto transmission should last for over 10 million miles. *


Your engine will break down long before your transmission will if you drive it right. I've seen older model BMWs with their tranny intact but the engine completely shot to hell...And the tranny looks like they can take years and years of abuse.

10 million miles? Hardly. A few hundred? More than likely.


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