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Braking by Downshifting - Good or Bad Idea?

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I did a quick (very quick) search and didn't come up w/ much, but I was wondering if downshifting to slow down is a good or bad idea. Obviously it helps the brakes out, but is it harmful at all to the gearbox, transmission, clutch, etc?
 
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Deuce B said:
I don't know the correct answer, but I've always figured I'd rather buy new brake pads before a new clutch. I use the brakes.

Deuce B is correct: the transmission was/is not designed to reduce the speed of a car. To use the trany as a braking mechanism is to abuse it and shorten it's useful life.

Use the brakes to slow your car; they can do it without the aid of the transmission. As Deuce B wrote, brake pads, rotors and brake fluid are inexpensive compared to replacing a clutch and/or rebuilding a transmission.
 
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I don't use the transmission to slow down in normal driving.
But a transmission is up to the task of transmitting energy in
either direction. Engine braking is good practice on long downhills.

There are a couple roads in my neighborhood that gain
3500' of elevation in 8 miles. You won't like what happens
to your brakes if you don't use the engine to dissipate
some energy on the descent.
 
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Tom239 said:
Engine braking is good practice on long downhills.

There are a couple roads in my neighborhood that gain
3500' of elevation in 8 miles. You won't like what happens
to your brakes if you don't use the engine to dissipate
some energy on the descent.
That's more choosing the correct gear to maintain speed rather than to slow down as in the original question.

Of course there are exceptions to everything, but in general, I think it's better to use the vehicles brakes rather than downshifting to slow down.
 

W

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Tom239 said:
There are a couple roads in my neighborhood that gain
3500' of elevation in 8 miles. You won't like what happens
to your brakes if you don't use the engine to dissipate
some energy on the descent.

I wouldn't hesitate to coast in neutral, really. It's not like you're riding the brakes down a hill. 8 miles or whatever down 3500 feet is nothing like 5 minutes on the track.
 
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Downshifting to get slower is a bad idea because that can block your rear wheels which may cause a spin.

OTOH: Staying in gear with clutch engaged when you come to a red signal light or coasting down a hill saves fuel with modern engines. You need less fuel than in neutral, caused by something we call "Schubabschaltung" in german - don't know the english word for it.
 
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it will kill the clutch and tranny if you don't know what you're doing. If you make sure to rev match/ heel-toe brake and can ensure smooth gear engagement while downshifting, you'll be ok but if you're downshifting to brake and the car's jolting cuz you allow your RPMs to drop too low for the next lower gear, something's gonna give if you continue at this, and it won't be the brakes.
 
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W said:
I wouldn't hesitate to coast in neutral, really. It's not like you're riding the brakes down a hill. 8 miles or whatever down 3500 feet is nothing like 5 minutes on the track.
You might prefer not to coast in neutral down this road in my neighborhood:

6825hmr.jpg
 
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FormulaRX said:
it will kill the clutch and tranny if you don't know what you're doing. If you make sure to rev match/ heel-toe brake and can ensure smooth gear engagement while downshifting, you'll be ok but if you're downshifting to brake and the car's jolting cuz you allow your RPMs to drop too low for the next lower gear, something's gonna give if you continue at this, and it won't be the brakes.


Ditto :biggrin:
 
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I always try to downshift and revv match, however downshifting from 3rd to 2nd is always a chore.

Sometimes it not enough revvs, which make the tranny work hard, and sometimes it's too much revvs, which lunges the car forward.

I guess its because 3 to 2 is a greater difference than 5-4, 0r 4-3???

Once my clutch goes (hopefully thats all) I'll replace it. Not to get off subject , but if you really want to try to FRY your clutch, just try to back your NSX up car ramps....mmmmmmmmmm smells good :eek:
 
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NSXVURGIN said:
Not to get off subject , but if you really want to try to FRY your clutch, just try to back your NSX up car ramps....mmmmmmmmmm smells good :eek:

You're from the bay area...aren't the streets of SF steep enough to fry your clutch on daily drives? :biggrin: :tongue:
 
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MarkB said:
My dictionary defines Schubabschaltung as overrun cutoff. Given the definition, does it mean that the fuel is cutoff in those situations?
Yes, Mark, thanks for the translation. You have nearly zero fuel consumption in this case - in contrary to engine idle at neutral which needs some fuel.
 
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