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  #1  
Old 07-19-2012, 09:11 AM
Nars Glinley Nars Glinley is offline
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When would I manually shift gears with my automatic transmission?

Like most (all?) people, I put my car in "D" and go about my driving business. But next to the big D, there's a "3 2 1". Are there any good situations to use them? I can kind of (maybe) see the usefulness of first gear but the other two just seem completely unnecessary.
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  #2  
Old 07-19-2012, 09:15 AM
mecaenas mecaenas is offline
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When going downhill for an extended period of time you can put the car into a lower gear to slow you down so you don't ride the brakes.
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  #3  
Old 07-19-2012, 09:15 AM
Alka Seltzer Alka Seltzer is offline
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One situation where you might want to lock the car in a particular gear is driving in icy conditions. You don't want the car changing down while going around a sharp corner, as the increase in torque can cause the wheels to break traction. This actually happened to my driving instructor once, it changed down to first and he had a very slow speed collision with a hedge.
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  #4  
Old 07-19-2012, 09:46 AM
MacdaddyC MacdaddyC is offline
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I use my 3 gear to while towing. Using D can burn out your overdrive.
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  #5  
Old 07-19-2012, 10:00 AM
jz78817 jz78817 is offline
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Originally Posted by MacdaddyC View Post
I use my 3 gear to while towing. Using D can burn out your overdrive.
while that may have been the case in the early days of 4-speed transmissions, the reason nowadays is because overdrive can drop the engine too low in its powerband for towing anything effectively.
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  #6  
Old 07-19-2012, 10:11 AM
Nars Glinley Nars Glinley is offline
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Originally Posted by MacdaddyC View Post
I use my 3 gear to while towing. Using D can burn out your overdrive.
My Chevy truck has a towing mode button on the gear shift although I don't think I've ever used it. How is that different than putting it in 3?
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  #7  
Old 07-19-2012, 10:14 AM
Mdcastle Mdcastle is offline
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When driving in hilly areas I tend to manually downshift one gear since it's easier to maintain a constant speed. As already noted it provides engine breaking going downhill. Going uphill the car would eventually downshift itself, but usually loses speed first before it reacts. This is the most common scenerio, going from Overdrive (4) to (3), so often there's a button you can just push to save you the trouble of moving a big lever...

(2) and (1) are generally less useful, except for for some situations off-roading in a 4wd vehicle, (Though I could maybe see (2) for engine braking on *very* steep roads). My Jeep Grand Cherokee has them being off-road capable but some vehicles omit them (like my sisters Toyota Corolla).

In addition 4 wheel drive vehicles have a shifter for the transfer case, for my full time 4WD its [Hi] for normal driving [Neutral] to disengage for being towed, and [Lo] for when you need a lot of power as opposed to speed, say extreme off-roading or pulling a boat out of a lake.
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  #8  
Old 07-19-2012, 10:15 AM
Machine Elf Machine Elf is offline
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Back in the '80's and '90's, my dad took us on summer vacations to the western US in a station wagon towing a pop-up camper. Some of these station wagons (he went through several over the decades) had overdrive on them. In cruise control on a level highway everything was fine, the transmission stayed in top gear. But if we came to a significant hill, the speed dropped and the cruise control put the throttle down enough to make the transmission downshift. With the extra torque at the wheels, the speed climbed back up, the cruise control eased up on the throttle, and the transmission upshifted - and then the decel-downshift-accel-upshift cycle would repeat until we crested the hill. The solution was to wait until the first automatic downshift as the climb began, and then move the PRND321 selector down a notch to hold it in that lower gear until cresting the hill. For even slower ascents on very steep mountain grades, you could just as easily select a lower gear - 1 or 2, depending on the grade and twistiness of the road. If you've never been to the mountainous areas of the western US - especially away from major interstate highways - the roads can be graded pretty steeply, and there are often switchbacks and squiggles that necessitate a very low speed.

If we were going to descend a long mountain grade, letting the transmission stay in overdrive would allow the whole rig to build up a lot of speed, requiring heavy braking to keep it within reason. Solution: when cresting the grade, if a long, steep descent was awaiting us, we'd leave the PRNDL321 selector in the lower position that we had chosen for the climb. You still needed some braking, but not nearly as much as if the transmission were in top gear.

Most small, lightweight cars won't be towing much of anything, but if they've got a low power-to-weight ratio and/or if they're carrying a full load of people and cargo, they'll still struggle to climb mountain roads. Not only are those roads steep as described, but you're also at high altitude, typically above 5,000 feet in the Rockies, and the thin air up there robs the engine of a significant fraction of its output. So even though you're not dragging a trailer behind you, you may still want to force a lower gear to prevent the transmission from constantly upshifting-downshifting-upshifting-downshifting.
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  #9  
Old 07-19-2012, 04:32 PM
Kevbo Kevbo is offline
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Exactly what Machine Elf said. Flatlanders just don't get that you can have several miles of 7% grade, followed by a mile or so of 9%. Brakes are sized and designed to provide several full speed stops. They are not sized to control speed down multiple miles of mountain grade.
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  #10  
Old 07-19-2012, 04:42 PM
Lemur866 Lemur866 is offline
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I've also used 1 and 2 for very slow driving in terrible ice/snow/slush conditions, where I wanted to drive 5 miles per hour without having to ride the brake.
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  #11  
Old 07-19-2012, 05:08 PM
pulykamell pulykamell is offline
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Originally Posted by Lemur866 View Post
I've also used 1 and 2 for very slow driving in terrible ice/snow/slush conditions, where I wanted to drive 5 miles per hour without having to ride the brake.
I've always wondered how this works.

I drive a stick. When I'm in really slick or snowy conditions, I may start from a standstill in 2nd gear instead of first, so as not to be as likely to spin my tires. Now, in an auto "1" and "2" will limit the gear selection to first gear, and to first and second gear, respectively, right? When you're driving 5 miles per hour, why would an auto be outside of 1st gear? "2" doesn't mean second gear, does it? It means first and second, no? So when you're at 5 mph, why would you be riding the brakes? Surely, the auto isn't past first gear at that speed, is it? At worst, I guess it might be on second, but I personally can't remember any autos I've driven where 5 mph would be anything but first gear.

Last edited by pulykamell; 07-19-2012 at 05:09 PM..
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  #12  
Old 07-19-2012, 05:23 PM
Skammer Skammer is offline
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Sometimes my car won't start out in first gear when the transmission is in D. I have to manually shift into first, get up to speed, then shift to D.

I realize that's a problem with my car somewhere and not a normal thing.
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  #13  
Old 07-19-2012, 05:24 PM
Encinitas Encinitas is offline
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If your brakes go out, you can gradually downshift to lessen your speed (somewhat) before you crash into something.
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  #14  
Old 07-19-2012, 05:27 PM
Lemur866 Lemur866 is offline
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All I know is if you have your foot off the gas in D you go forward faster than you do when you have your foot off the gas in 1.
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  #15  
Old 07-19-2012, 05:50 PM
pulykamell pulykamell is offline
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Originally Posted by Lemur866 View Post
All I know is if you have your foot off the gas in D you go forward faster than you do when you have your foot off the gas in 1.
This is interesting. Why would this be the case? I've personally never noticed this in my autos, but the last time I owned an auto was 20 years ago, so maybe things have changed.
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  #16  
Old 07-19-2012, 06:02 PM
pete66 pete66 is offline
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Quote:
Originally Posted by Nars Glinley View Post
My Chevy truck has a towing mode button on the gear shift although I don't think I've ever used it. How is that different than putting it in 3?
Tow/Haul mode doesn't keep you out of overdrive. It just adjusts when the transmission shifts. Usually it will delay the shift when climbing a grade to allow higher rpms before shifting, and shift earlier allowing more drag from the engine and transmission when descending. At least that appears to be what my dodge does.
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  #17  
Old 07-19-2012, 06:49 PM
kanicbird kanicbird is offline
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In some cars '2' will stay in 2 and not vary between 1 and 2. This allows you to start driving in second instead of first, useful on slippery conditions where 1 would spin the wheels.
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  #18  
Old 07-19-2012, 07:07 PM
Simple Linctus Simple Linctus is offline
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Quote:
Originally Posted by Nars Glinley View Post
Like most (all?) people, I put my car in "D" and go about my driving business. But next to the big D, there's a "3 2 1". Are there any good situations to use them? I can kind of (maybe) see the usefulness of first gear but the other two just seem completely unnecessary.
Not to be rude, but if you're asking this question then in a sense the answer is no - there are no good situations where you would use them.

There are umpteen reasons why a good driver would want to use them. These can be broken down into either car handling reasons where you would not want the car to suddenly upshift (or downshift if it were in a higher gear) (which in the worst cases could cause an instant spin if the car were near the limit of adhesion) or roadcraft reasons where as a driver more intelligent than the gearbox you either want the engine in a different part of its powerband (e.g. you anticipate overtaking someone soon, which if you're doing it properly you don't want to be just relying on kickdown) or you want increased engine braking (such as the hills example). If your gearbox is crap then there is a reason 2.5 , you want to stop it from hunting.

If you are interested in being a good road driver, although it is a British book it is still the one to start with - Roadcraft: The Police Driver's Handbook. It teaches a system to use in all aspects of driving that is the foundation of pretty much all advanced driving groups I am aware of.
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Old 07-19-2012, 07:56 PM
pulykamell pulykamell is offline
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Originally Posted by kanicbird View Post
In some cars '2' will stay in 2 and not vary between 1 and 2. This allows you to start driving in second instead of first, useful on slippery conditions where 1 would spin the wheels.
That's interesting. The automatics I've had didn't work this way, but that would make sense to start in 2 in slippery conditions if the transmission locks into second gear and skips over first. What doesn't make sense is why "D" would accelerate faster than "1" with the foot off the brake, as in Lemur's case. Wouldn't both transmissions be in first in that case? Why would riding the brake in "D" cause the car to go faster than riding it in "1"? I could believe it's some quirk of autos, but I'd be interested in hearing what's going on to make this the case.
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  #20  
Old 07-19-2012, 08:00 PM
Nars Glinley Nars Glinley is offline
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Originally Posted by Confused dart cum View Post
Not to be rude, but if you're asking this question then in a sense the answer is no - there are no good situations where you would use them.
Not into the whole fighting ignorance thing, are you?
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  #21  
Old 07-19-2012, 10:20 PM
Mdcastle Mdcastle is offline
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Also I've noticed a number of people haven't the foggiest idea what a tach is, and how it can be useful if you manually shift gears.
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  #22  
Old 07-19-2012, 10:42 PM
GameHat GameHat is offline
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Manual transmission guy speaking here: I drive a 5-speed 2007 Mustang GT. Nice little entry-level "performance" car.

Typically, you want the lower gears for either speed limiting (going downhill without wearing out your brakes) or for passing. I'll discuss snowy driving as well (I live and drive in the upper midwest, where snow, ice and sleet are common in winter months.)

If you have a long downhill stretch (mountains) it may be better to keep the car in a low gear (probably 2nd) to ease the load on your brakes. This is more applicable for semi trucks - they're huge, heavy, and they can absolutely ruin their brakes and lose control if they don't downshift on long hills. But most cars can handle the braking necessary on long downhill stretches, unless you're doing it every day, repeatedly. But it is helpful. I do have one steep hill in my normal driving area; when I'm going down it it's nice to just put the car in 2nd to have more speed control and not have to stand on the brake pedal.

3rd gear on most cars is a good "passing" gear - meaning, you're on the highway, you want to pass someone. 3rd gear is good for getting reasonably quick acceleration without putting your tach into the redline. I do this all the time. The difference here between manual and auto trannys is that in all the autos I've driven, you shift to the left (passing) lane, floor it, and whatever controls the auto takes a few seconds to realize you really want to go fast. In a manual, you just shift and go.

As for snow/ice - and I say this driving a RWD Mustang near Chicago (So I am familiar with driving in snow with a car totally unsuited for such a thing):

If you get stuck on a slippery area, having control of the gear is very helpful. An earlier poster suggested that 2nd is the gear you want; I disagree, at least for my vehicle. What you really need to do to get moving on snow or ice is first: Disable traction control. Traction control kills power to the wheels if it senses that they're slipping. Traction control is a great safety feature when the car is in motion; it's terrible for getting the car moving.

Personally, I've had the best luck putting it in 1st with traction control off, and giving it a good amount of throttle. Often you end up going forward a bit, then losing traction and spinning the wheels. Then you want to put it in reverse, and again, give it a good amount of throttle. I usually end up rocking back and forth a bit, but I've never gotten stuck. Just keep rocking back and forth until you get the momentum to keep going.

Once you're moving on snow and ice, absolutely turn traction control back on. It really is a good safety feature, it just makes it harder to get started.

Last edited by GameHat; 07-19-2012 at 10:43 PM..
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  #23  
Old 07-19-2012, 10:59 PM
pulykamell pulykamell is offline
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Quote:
Originally Posted by GameHat View Post
=

If you get stuck on a slippery area, having control of the gear is very helpful. An earlier poster suggested that 2nd is the gear you want; I disagree, at least for my vehicle. What you really need to do to get moving on snow or ice is first: Disable traction control. Traction control kills power to the wheels if it senses that they're slipping. Traction control is a great safety feature when the car is in motion; it's terrible for getting the car moving.
Traction control? Fancy pants car.

For the vehicles I've had, in slippery situations, both snow and rain, personally, I've found it easier to start from second, as it's really easy to spin the tires in first. I generally try not to do the rocking-back-and-forth action, as it tends to make a bad situation worse. I try to slowly ease out and get traction, if I can. Admittedly, sometimes, you just gotta rock it. If you look it up, starting in a higher gear for slippery situations is fairly standard advice. YMMV.

Looking it up, it does seem that in a lot of automatics these days, 2 means "second gear only" and not "first and second." I could swear my in my 80s and 90s era automatics, "2" meant limiting the gears to first and second, but perhaps I was not as observant back then as I am now, as I didn't drive sticks until the late 90s.
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Old 07-19-2012, 11:59 PM
Kenm Kenm is offline
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Originally Posted by kanicbird View Post
In some cars '2' will stay in 2 and not vary between 1 and 2. This allows you to start driving in second instead of first, useful on slippery conditions where 1 would spin the wheels.
Years ago, this was the case with Fords and was very handy in snow or on ice. But it was not the case with GMs or Chryslers, and isn't now. I don't know whether Ford stuck with it.
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  #25  
Old 07-20-2012, 02:39 AM
AaronX AaronX is offline
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Originally Posted by Alka Seltzer View Post
One situation where you might want to lock the car in a particular gear is driving in icy conditions. You don't want the car changing down while going around a sharp corner, as the increase in torque can cause the wheels to break traction. This actually happened to my driving instructor once, it changed down to first and he had a very slow speed collision with a hedge.
To my knowledge, gear "2" on automatics means the max gear the transmission will choose is 2, it may also choose 1. To those people who say it will only choose 2 - can you get your car to shudder/stall on 2? Or, launch the car in 1 and immediately shift to 3. Does the car change gears when you shift?

So, as people have said, it limits the gears your transmission will choose, for:
1. more power (climbing)
2. engine braking (downhill), also if your brakes don't work
3. traction
Something nobody has mentioned: if you want the fastest acceleration, you should stay in lower gears longer before shifting, but cars normally don't do that because it wastes fuel. So you can "manually" upshift using the gears on an automatic to accelerate faster.

The interesting thing is - what was the main reason to have those gears on automatics - performance or safety? If engine braking required higher gears, would automatic transmissions limit the MINIMUM gear, or still the maximum?

Last edited by AaronX; 07-20-2012 at 02:40 AM..
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  #26  
Old 07-20-2012, 03:26 AM
bengangmo bengangmo is offline
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Originally Posted by AaronX View Post
To my knowledge, gear "2" on automatics means the max gear the transmission will choose is 2, it may also choose 1. To those people who say it will only choose 2 - can you get your car to shudder/stall on 2? Or, launch the car in 1 and immediately shift to 3. Does the car change gears when you shift?

So, as people have said, it limits the gears your transmission will choose, for:
1. more power (climbing)
2. engine braking (downhill), also if your brakes don't work
3. traction
Something nobody has mentioned: if you want the fastest acceleration, you should stay in lower gears longer before shifting, but cars normally don't do that because it wastes fuel. So you can "manually" upshift using the gears on an automatic to accelerate faster.

The interesting thing is - what was the main reason to have those gears on automatics - performance or safety? If engine braking required higher gears, would automatic transmissions limit the MINIMUM gear, or still the maximum?
Cars are continually getting better and more intelligent with their shifting patterns. I know some brands that have a "snow" setting for the auto, that will start it in second.
On top of this, the way that an automatic works is inherently more gentle than a manual.

But I would also need to point out, in my auto if I mash it for max acceleration, the car will hold the gear until redline before shifting - so the short shifting you are referring to may not neccessarily be true.
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Old 07-20-2012, 05:27 AM
Alka Seltzer Alka Seltzer is offline
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Originally Posted by AaronX View Post
To my knowledge, gear "2" on automatics means the max gear the transmission will choose is 2, it may also choose 1. To those people who say it will only choose 2 - can you get your car to shudder/stall on 2? Or, launch the car in 1 and immediately shift to 3. Does the car change gears when you shift?
I think you'd need to check the manual of the particular car to be sure. From the wiki article:

Quote:
Second (2 or S)
This mode limits the transmission to the first two gear ratios, or locks the transmission in second gear on Ford, Kia, and Honda models.

Last edited by Alka Seltzer; 07-20-2012 at 05:27 AM..
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  #28  
Old 07-20-2012, 07:05 AM
AaronX AaronX is offline
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Ok the instructions for the 2011 Honda Accord say 2 locks the transmission, but D3 may select lower gears. 2011 Toyota Camry says it'll select that and lower gears. I guess second gear is powerful enough to do without first.
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  #29  
Old 07-20-2012, 07:22 AM
Broomstick Broomstick is offline
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Originally Posted by pulykamell View Post
Surely, the auto isn't past first gear at that speed, is it? At worst, I guess it might be on second, but I personally can't remember any autos I've driven where 5 mph would be anything but first gear.
Automatics will roll forward in D without your foot on the accelerator, it's called "idle speed" or something of the sort. In many automatic cars that speed can be faster than 5 mph. In other words, you have to ride the brake in D to slow it down to 5 mph. Putting it into a lower gear gives it a lower idle speed and eliminates the need to ride the brake.

Why is it done that way? Haven't the foggiest notion, but I can always spot someone who's only driving experience is with manuals because they don't know about that quirk and/or are surprised by the car wanting to creep/roll forward in D without input from them.
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Old 07-20-2012, 07:44 AM
pulykamell pulykamell is offline
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Originally Posted by Broomstick View Post
Automatics will roll forward in D without your foot on the accelerator, it's called "idle speed" or something of the sort. In many automatic cars that speed can be faster than 5 mph. In other words, you have to ride the brake in D to slow it down to 5 mph. Putting it into a lower gear gives it a lower idle speed and eliminates the need to ride the brake.
I do know about riding the brake in automatics. But wouldn't you be in first gear off the line whether you're in D or 1 on an automatic? This is what I'm wondering about. Plus, off the line, the lower gear should accelerate faster to 5 mph than the higher one, anyway, if D starts you off in anything but first. I guess I could see that if the auto switches to second by 5 mph, it should eventually coast faster, but is the shift point that low?
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Old 07-20-2012, 07:53 AM
TonySinclair TonySinclair is offline
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Originally Posted by GameHat View Post
Typically, you want the lower gears for either speed limiting (going downhill without wearing out your brakes)
It's cheaper to get new brakes than a new engine. Is it definite that long downhill stretches of engine braking don't decrease the life of your engine?
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Old 07-20-2012, 08:07 AM
Broomstick Broomstick is offline
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Originally Posted by pulykamell View Post
I do know about riding the brake in automatics. But wouldn't you be in first gear off the line whether you're in D or 1 on an automatic? This is what I'm wondering about. Plus, off the line, the lower gear should accelerate faster to 5 mph than the higher one, anyway, if D starts you off in anything but first. I guess I could see that if the auto switches to second by 5 mph, it should eventually coast faster, but is the shift point that low?
Honestly.... I don't know. My current car has a computer that, when it comes to driving matters, is smarter than I am. I don't know how it was programmed but these days either alternative is possible.
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Old 07-20-2012, 08:17 AM
Richard Pearse Richard Pearse is online now
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Originally Posted by TonySinclair View Post
It's cheaper to get new brakes than a new engine. Is it definite that long downhill stretches of engine braking don't decrease the life of your engine?
But you need to get new brakes while you own the car, a new engine will most likely be someone else's problem.
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Old 07-20-2012, 08:19 AM
Rick Rick is offline
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Originally Posted by TonySinclair View Post
It's cheaper to get new brakes than a new engine. Is it definite that long downhill stretches of engine braking don't decrease the life of your engine?
No it does not.
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Old 07-20-2012, 09:02 AM
jz78817 jz78817 is offline
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Originally Posted by TonySinclair View Post
It's cheaper to get new brakes than a new engine. Is it definite that long downhill stretches of engine braking don't decrease the life of your engine?
No. "engine braking" means using the pumping losses of the engine trying to draw air through a closed throttle combined with a lower gear ratio to slow the car. It does not cause any additional wear in the engine of any consequence.
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Old 07-20-2012, 09:09 AM
Nars Glinley Nars Glinley is offline
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Originally Posted by TonySinclair View Post
It's cheaper to get new brakes than a new engine. Is it definite that long downhill stretches of engine braking don't decrease the life of your engine?
It won't be cheaper if your brake fluid boils and you can't stop when needed.
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Old 07-20-2012, 09:35 AM
Machine Elf Machine Elf is offline
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It's cheaper to get new brakes than a new engine. Is it definite that long downhill stretches of engine braking don't decrease the life of your engine?
Your engine is likely to last for a few thousand hours of run time. Over the life of your vehicle, deliberate engine braking is not likely to compose more than an hour of that time. Moreover, engine braking puts less load on the engine than highway cruise, and with lower temperatures (since little or no fuel is being burned in the combustion chambers. Wear due to engine braking will be negligible.

If you are descending a miles-long 9% mountain grade with a car full of meat and/or cargo, using the friction brakes to decelerate from 80 MPH down to 60 MPH three times per minute for a few minutes stands a fair chance of cooking your brakes. You may warp the rotors, you may experience reduced braking capacity due to brake fade (pad friction coefficient reduces at very high temperature) or in severe cases (especially with moisture-contaminated brake fluid) you may boil the brake fluid and lose braking ability altogether.

Descending a one-block-long hill in San Francisco at 20 MPH? Don't bother downshifting your automatic transmission; your friction brakes will do just fine here.

Quote:
Originally Posted by AaronX
Something nobody has mentioned: if you want the fastest acceleration, you should stay in lower gears longer before shifting, but cars normally don't do that because it wastes fuel.
Automatic transmissions will shortshift if you're light on the throttle - but if you've got your foot to the floor, the computer will not shift until RPM's are at or near the redline; no need to use the selector to delay the shift.

Quote:
Originally Posted by Lemur866
All I know is if you have your foot off the gas in D you go forward faster than you do when you have your foot off the gas in 1.
If the transmission is not in neutral, the car wants to creep forward until the engine is idling at the same speed it would idle at in neutral*. If you let it upshift (i.e. the selector is in "2" or "D"), then once the car gets going fast enough, it will shift up to a higher gear and end up idling forward faster than if you had held it down in first gear. Listen/feel carefully (especially if you've got a tachometer on the display), and you can probably tell where the shift is.

*late-model vehicles may open the throttle slightly when you put the transmission in gear so as to avoid having the RPM's drop precipitously, so if you let it roll forward at its desired speed, the RPM may end up being higher than you would see if you were stopped with the selector in "P" or "N".
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  #38  
Old 07-20-2012, 09:54 AM
kanicbird kanicbird is offline
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To answer the question about cars that 2nd means 2nd only. There is no problem with the engine studdering, it appears the car is just as happy starting out from a stop in 2nd as 1st, though with less acceleration.

Also some automatic cars with a 'manumatic' mode, meaning you control the shifting of a automatic transmission by moving a shifter to up/downshift - autoshifting doesn't happen, allow the start from a stop in 2nd by using the manumatic mode. Subaru is one such manufacturer, at least some of their older models, where to start out in 2nd you would have to use the manumatic shifter to change from 1 to 2 at the stop, then you start out in 2.
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  #39  
Old 07-20-2012, 10:52 AM
pulykamell pulykamell is offline
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Originally Posted by kanicbird View Post
To answer the question about cars that 2nd means 2nd only. There is no problem with the engine studdering, it appears the car is just as happy starting out from a stop in 2nd as 1st, though with less acceleration.

Also some automatic cars with a 'manumatic' mode, meaning you control the shifting of a automatic transmission by moving a shifter to up/downshift - autoshifting doesn't happen, allow the start from a stop in 2nd by using the manumatic mode. Subaru is one such manufacturer, at least some of their older models, where to start out in 2nd you would have to use the manumatic shifter to change from 1 to 2 at the stop, then you start out in 2.
Hell, with some of the really torquey cars, you can even start in 3! (My friend's 2012 Camaro is a manumatic with paddle shifters, and I was surprised that it would let me select 3 to start in manual mode. But not 4. )
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  #40  
Old 07-20-2012, 11:32 AM
Kevbo Kevbo is offline
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Originally Posted by TonySinclair View Post
It's cheaper to get new brakes than a new engine. Is it definite that long downhill stretches of engine braking don't decrease the life of your engine?
It is even more expensive to haul the remains of your car out of the ravine* and and embalm and bury your corpse after you boil your brake fluid and fail to make that last hard turn on a mountain grade. Yes, brakes are far better now than they used to be, assuming they are maintained. When was your brake fluid last replaced? How much lining do you have left on your pads? Are your brake hoses in good condition or are they getting spongy?

Engine braking lightly loads the back sides of gear teeth, and the opposite half of journal bearings that see very little wear otherwise. It is at fairly high RPM giving full oil pressure and low forces, so wear is virtually nil. Yes it adds some minute wear, but it is wear to areas that won't wear out anyway, and will still be fine long past the point where wear from normal driving requires replacement or rebuild of components. Many modern engine control units completely stop the flow of fuel under these conditions, so it can actually use less fuel than riding the brakes.

It is absolutely false to say that brakes were designed to control speed and transmissions/torque converters/clutches/etc. were not. The existence of options other than "D" betrays the fact that the designers envisioned valid uses of those selections.



*expensive enough that they often just leave the dead cars to rust away.
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  #41  
Old 07-20-2012, 10:31 PM
GameHat GameHat is offline
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Originally Posted by pulykamell View Post
Traction control? Fancy pants car.

For the vehicles I've had, in slippery situations, both snow and rain, personally, I've found it easier to start from second, as it's really easy to spin the tires in first. I generally try not to do the rocking-back-and-forth action, as it tends to make a bad situation worse. I try to slowly ease out and get traction, if I can. Admittedly, sometimes, you just gotta rock it. If you look it up, starting in a higher gear for slippery situations is fairly standard advice. YMMV.

Looking it up, it does seem that in a lot of automatics these days, 2 means "second gear only" and not "first and second." I could swear my in my 80s and 90s era automatics, "2" meant limiting the gears to first and second, but perhaps I was not as observant back then as I am now, as I didn't drive sticks until the late 90s.
Hey, I'm just speaking from experience

I'm talking getting started in snow that has piled up to halfway the height of the tire.

Spinning the tires is almost always bad. You're just compressing the snow/ice into a slick nightmare. When I talk about rocking I mean move forward until the tires slip, quickly shift, move in reverse till the tires slip, back into 1st, repeat.

That said - In heavy snow/ice I've tried 2nd gear, and it just simply doesn't work (in my car). You really need to get momentum - I can get my car moving on dry asphalt in 2nd (or even 3rd, the few times I've made the mistake of thinking 3rd was 1st) but on an icy, slippery road - only 1st will do.

And yeah, I have traction control, but for getting the car going from a stop in icy conditions - it needs to be off.

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  #42  
Old 07-21-2012, 01:50 AM
AaronX AaronX is offline
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Originally Posted by Machine Elf View Post
Automatic transmissions will shortshift if you're light on the throttle - but if you've got your foot to the floor, the computer will not shift until RPM's are at or near the redline; no need to use the selector to delay the shift.
Do you mean if I were to drag race an automatic car, all I have to do is floor the accelerator?
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  #43  
Old 07-21-2012, 05:34 AM
Richard Pearse Richard Pearse is online now
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Originally Posted by AaronX View Post
Do you mean if I were to drag race an automatic car, all I have to do is floor the accelerator?
Yeah, if you want quick acceleration in an automatic, say if you want to overtake someone, floor the accelerator and it'll drop down a gear and shift at, or close to, the red line.
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  #44  
Old 07-23-2012, 12:44 AM
Satellite^Guy Satellite^Guy is offline
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Originally Posted by pulykamell View Post
Hell, with some of the really torquey cars, you can even start in 3! (My friend's 2012 Camaro is a manumatic with paddle shifters, and I was surprised that it would let me select 3 to start in manual mode. But not 4. )
When I took driver training (in a manual), back in 1990, my instructor demonstrated that you can start a car in any gear, without using any throttle, by putting it in every gear, and gently letting up on the clutch, enough to get it rolling. He then got me to do it in 1st gear. I guess this teaches one to be gentle with the clutch, to eliminate jerky starts.
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  #45  
Old 07-23-2012, 02:26 AM
pulykamell pulykamell is offline
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Originally Posted by Satellite^Guy View Post
When I took driver training (in a manual), back in 1990, my instructor demonstrated that you can start a car in any gear, without using any throttle, by putting it in every gear, and gently letting up on the clutch, enough to get it rolling. He then got me to do it in 1st gear. I guess this teaches one to be gentle with the clutch, to eliminate jerky starts.
I'll have to see if my Mazda 3 will be able to roll in 3 or 4 without stalling. I'm curious. As for the technique you describe, that's how I generally teach people inexperienced with driving stick. I get them to get the car moving in first without using the throttle to get a sense of where the grabbing/release point is, and it also nips bad habits like throttling hard and aggressively slipping the clutch before they can start to form.
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Old 07-23-2012, 08:06 AM
Machine Elf Machine Elf is offline
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Originally Posted by AaronX View Post
Do you mean if I were to drag race an automatic car, all I have to do is floor the accelerator?
Got an auto-trans car? Next time you're all alone at a red light, floor the accelerator when the light turns green: you'll see the tach touch redline just as the transmission shifts into second (and third, and overdrive, if you care to get going that fast). Can't do much better than that.

People who turn street cars into competition drag racers will refit their cars with (among other things) a couple of helpful features:

-a torque converter on the transmission with a stall RPM that's maybe 1000-2000 RPM below the RPM at which the engine delivers peak torque, and

-a rev limiter that interrupts the spark at an RPM just below the torque converter's stall RPM, until the driver releases a switch (at which point the original redline RPM limiter is restored to duty).

So when you're a couple of seconds from launching down the track, you hold the button for the low-RPM rev limiter, and you flatfoot the throttle. The low-RPM rev limiter holds the engine at maybe 3500 RPM or so, just below the point where the torque converter starts delivering heavy torque. When the tree turns green, you release the switch, the engine starts delivering all its power, and now the rev limiter lets the engine spin up - and it only has to spin up a little bit before you start getting full torque delivery. Yahoooooooo....
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