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Manual Driving question downshifting to brake

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Old 7/5/06, 06:17 PM
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Originally Posted by MadMark
It is actually illegal in many states to "coast" in neutral while driving.
My state refers to coasting, but they mean with the engine OFF. Coasting with the engine on would be impossible to completely avoid.
One NH law states only downhill coasting is illegal.
265:99 Coasting Prohibited. –
I. The driver of any vehicle when traveling upon a downgrade shall not coast with the gears of such vehicle in neutral.
II. The driver of a truck or bus when traveling upon a downgrade shall not coast with the clutch disengaged.
III. The fine for a violation of this section shall be $100.
Old 7/5/06, 06:22 PM
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Originally Posted by Tony Alonso
Others might disagree, but using engine braking to slow the car down when you are traveling on a flat surface puts unnecessary wear and tear on a more expensive set of components to replace - the drivetrain. Pads and rotors are designed for the purpose of stopping the car. The only time I ever downshift to slow is on a steep incline when there is traffic ahead.

It is my opinion that some people mainly use this procedure for show.

Couldn't have said it better myself!
Old 7/5/06, 06:24 PM
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I too have always been taught to downshift and not coast to a stop with a 5-speed. If you want to do this, just like the guy above stated, you need to blip the throttle and match the revs. I fyou just downshift without giving it some gas, your add too much strain to the clutch. When you do add some throttle, just make sure its enough to make the downshift not feel jerky. And about the clutch wear. These cars aren't set up like exotic sports cars, where their clutches wear out after 5,000 miles. These are more set up for everyday driving, and can take some abuse, as stated by some above with many thousands of miles driven.
Old 7/5/06, 06:24 PM
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I have had 5 manual cars and downshifted every last oneof them. Never changed a clutch in any of them nor did I have any other problems that I knew of.

There is no way I would put this car in N unless im at a stop...the o/r H with frpp's sound WAY to good to do that...and i dont think it will mess anything up. Besides if it does that more the reason to get a better clutch and so on and so forth!
Old 7/5/06, 07:38 PM
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For the record, I think you will find people in either camp on this. I personally was never taught to do this and don't consider the extra effort to slow down strictly with engine braking worth the extra shifting. In addition, driveline shock is the kind of wear to which I was originally refering.

As some have mentioned, if you do this, matching the engine RPMs to engage the gear smoothly is key.
Old 7/5/06, 07:49 PM
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I do a little of both depending on the situation and or mood I'm in. I didn't buy this car to baby it. If you are just using the brakes, you should still kept the car in the appropriate gear for the speed just in case you need to get on the gas quickly to avoid anything in the street or knuckleheads(non driving drivers).
Old 7/5/06, 08:38 PM
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Originally Posted by karman
My state refers to coasting, but they mean with the engine OFF. I believe this is what is illegal, not with the engine on as that would be impossible to completely avoid.
While driving with the engine off is certainly illegal, it is also illegal in many states to drive in neutral.

The reasoning is that you lose some of your stopping power being out of gear, and also if for some reason you need to accelerate around something, although I doubt anyone would enforce it.
Old 7/5/06, 09:19 PM
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Originally Posted by MadMark
While driving with the engine off is certainly illegal, it is also illegal in many states to drive in neutral.

The reasoning is that you lose some of your stopping power being out of gear, and also if for some reason you need to accelerate around something, although I doubt anyone would enforce it.
Unless there's something I don't know, how could it be accurately enforced? I mean, it's not like cops drive around with a neutral-o-meter or anything, lol.
Old 7/5/06, 09:40 PM
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I agree with Louie! I have had 4 Mustangs with a manual and I down shift while braking all the time. I had no problems with the motor or transmission.

1983 GT - No Problems - 110,000
1990 GT - No problems - 113,000
1995 Cobra - replaced clutch because of a bad through-out bearing (90,000) still had many miles on the clutch - 107,000+ (still going strong)
2006 GT - No Problems - 12,000

It doesn't hurt it unless you let it over rev. Besides if the new Mustang can't handel down shifting while braking then it isn't worth a hoot and we all know its the best Mustang ever!
Old 7/6/06, 06:43 AM
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[quote=95SVTCobraVA]
1995 Cobra - replaced clutch because of a bad through-out bearing (90,000) still had many miles on the clutch - 107,000+ (still going strong)
quote]

That bad throw-out bearing had nothing to do with your driving... it was a problem that all T-5s and T-45s had for a number of years.... I had it on my '98 GT too.
But ayways... I'd agree with the rev matching. I'll do it especially if I'm downshifting hard on a slippery surface... 'cause it'll get a little squirrely.... but, yeah.. Good times.
Old 7/6/06, 07:29 AM
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I don't know how my driving environment is so different from all of you that downshift. Or maybe I'm misunderstanding what you mean when you say downshifting to a stop. But when I'm coming to a stop I don't have time to shift into the next lower gear, clutch out, clutch in, next lower gear....

I'll be to a complete stop with just the brakes before I get through 2 gears.

My normal procedure is clutch in, put car in Nuetral and hold it between 1st and 2nd. That way it's ready if i need it.
Old 7/6/06, 08:45 AM
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Such a commom misconception about drivetrain wear by those who don't know. The proper and correct way is to downshift while braking. Does an automatic equipped transmission shift into neutral while braking? No, it also downshifts for the appropriate speed.

Coasting means you no longer have complete control of the car since your foot is no longer linked to the driven wheels.
Old 7/6/06, 08:57 AM
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Originally Posted by clintoris
That bad throw-out bearing had nothing to do with your driving... it was a problem that all T-5s and T-45s had for a number of years.... I had it on my '98 GT too.
Your correct, I had heard that those transmissions had a small problem with the through-out bearing but mine took 90,000 miles for it to become a problem. What I liked was that my clutch still had plenty of miles left on it when it was changed.

This new Mustang seems to be tough and should handel the down-shifting while braking with no problem at all. Of course time will tell!
Old 7/6/06, 08:59 AM
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Definitely don't

As some other people have said, this technique is NOT the best way to go.

The idea is that you change gear to match your speed. You should slow down, THEN change down. Obviously you still experience engine-braking, but you should not be using excessive engine braking instead of proper braking.

In England where I am, you would actually fail your driving test if you started using low gears for the purpose of slowing the car.
Old 7/6/06, 09:21 AM
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Originally Posted by davidb1243456
As some other people have said, this technique is NOT the best way to go.

The idea is that you change gear to match your speed. You should slow down, THEN change down. Obviously you still experience engine-braking, but you should not be using excessive engine braking instead of proper braking.

In England where I am, you would actually fail your driving test if you started using low gears for the purpose of slowing the car.
Like David said, if you shift correctly there should be no wear or damage problems. If you downshift at the right time there is very little strain put on any of the moving parts in the drivetrain. After all, they were designed for this type of use.

If the car drops 5 or 10 mph and your body lurches forward when you downshift, it was done waaaaay to early and that;s definitely not good for the car. In my car I find that if I am slowing down, the best time to downshift is around 1400-1600 rpms, depending of which gear I'm in and how quickly I'm deccelerating.
Old 7/6/06, 09:31 AM
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+1 on all the people that said the proper technique is to downshift while braking, this is a basic driving skill that used to be taught in driver's ed.

EDIT- here is some info off of Wikepedia, it doesn't seem to vindicate either side of the argument but rather presents both sides equally:

Compression braking

This is also called "engine braking"; the use of the engine's internal resistance to slow down the vehicle, or keep it from accelerating down a hill. This is done by shifting the car into a lower gear and releasing the clutch, with the foot off the throttle.
Some feel that you abuse your manual transmission and engine by "engine braking". They feel that you should downshift only when you anticipate that the car will be in a lower speed for some time, not when coming to a full stop. Some feel that the reason why you must keep the car in gear while slowing down or stopped but with the clutch disengaged is for emergency maneuvers, for it will give you the extra time to escape a pending accident. In this case, downshift late, allowing the car to slow to a pretty low engine RPM's before shifting down.

Using the manual transmission to stop the car is inappropriate under normal driving conditions. Simply put, when using the engine to slow the speed of the transmission, the clutch and synchronizers are unnecessarily being worn out for what the car brakes are designed to do. In comparison, the clutch typically costs around US$1,000 to fix as opposed to US$300 for new brake pads and installation. The method is provided only because one may find it occasionally necessary or useful to use engine braking (when one needs to decelerate more quickly than usual, for instance).

If decelerating towards a full stop while in an upper gear, such as 4th, a downshift to a lower gear should be made, as this increases the time that a gear is engaged, therefore keeping the brake and power steering servos engaged and so power is supplied. Coasting time should be kept to a minimum using effective and well-timed downshifts.

On the other side of the coin, some feel that engine braking is relatively harmless to the engine and transmission. The idea is that during decceleration the engine creates a vacuum in the cylinders which pull a very small amount of oil past the rings, increasing protection. This, combined with the fact that the forces involved are typically less than those normally seen during acceleration lead some to conclude that it will make no real difference in the lifetime of the engine and transmission.
There is a situation when engine braking is truly called for: going down steep hills which are also very long, and for whatever reason, it is undesirable to pull over and stop the car. Braking downhill for a long time can overheat the brakes leading to failure. A combination of gearing down and using the brakes is safer. But heat can be dissipated from brakes also by pulling the car over and letting it stop for a while, effectively dividing the long hill into a sequence of shorter ones.

In fact, drivers find that most of the time, the best manual transmission driving practices closely mimic the actions of an automatic transmission, except in cases when the automatic transmission lacks anticipation of changing conditions. To be a good manual transmission driver, drive an automatic and observe what it does. Modern engine and automatic transmission control (such as that found in the 2005 w:Toyota Tundra) incorporate downshifting the automatic transmission out of overdrive during braking, or when the car is coasting down hill faster than the cruise control setting.
Old 7/6/06, 09:51 AM
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people drive stick different ways...i mostely use my brakes....i only engine brake at high speeds to slow down the car. but hey we all learn a different way to do things right??
Old 7/6/06, 09:54 AM
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Brakes are cheaper then transmissions.
Old 7/6/06, 10:15 AM
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I try to match the gear with engine speed, so I'm always in that "sweet spot".
Old 7/6/06, 11:08 AM
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I hate it when people say that you shouldn't engine brake and then they have no backup. Where is your proof that engine braking wears out the clutch prematurely?

Guess what, normal engine braking puts WAY less strain on the drivetrain and clutch than hard acceleration does.

However, as others have said, rev-matching and braking while downshifting is the proper technique. I am generally too lazy to rev-match, so I used mild engine braking while using the brakes as well.

After going to school for mech. engineering, and owning 50+ vehicles (10 Mustangs) I think I would know whether or not this technique harms the drivetrain.


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