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Proper Shifting Of An Automatic........

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OK, I know this may sound like a rather stupid question, but, it has been on my mind a lot lately.

When is it OK to shift an automatic transmission car into Drive or Reverse in the morning when the engine is cold?

I've noticed that when I shift the car into gear when the tach is around 1,500- 1,600 rpms. or even slightly higher, the car kind of "lurches" or even sometimes "slams" into gear. I usually try to wait until the revs go under 1,400 rpms or so, but, sometimes it's simply not practical. When the car is warm and the revs are 800- 1,000 rpms, you can't even feel it shift at all hardly.

My question is, will I cause a lot of premature damage to my transmission if I continue to do this. It's not a problem in warmer months, because the warmup time is a lot shorter. In order for me to get the car idle to drop low enough in the winter months, I usually have to wait 3 to 4 minutes. It doesn't sound like a long time, but it can be an eternity when you are in a hurry!! Not to mention a waste of gas!!!

Any comments, opinions, or suggestions would be greatly appreciated!!!

Thanks!! default_smile

Regards,

timkedz

OK, I know this may sound like a rather stupid question, but, it has been on my mind a lot lately.

When is it OK to shift an automatic transmission car into Drive or Reverse in the morning when the engine is cold?

I've noticed that when I shift the car into gear when the tach is around 1,500- 1,600 rpms. or even slightly higher, the car kind of "lurches" or even sometimes "slams" into gear. I usually try to wait until the revs go under 1,400 rpms or so, but, sometimes it's simply not practical. When the car is warm and the revs are 800- 1,000 rpms, you can't even feel it shift at all hardly.

My question is, will I cause a lot of premature damage to my transmission if I continue to do this. It's not a problem in warmer months, because the warmup time is a lot shorter. In order for me to get the car idle to drop low enough in the winter months, I usually have to wait 3 to 4 minutes. It doesn't sound like a long time, but it can be an eternity when you are in a hurry!! Not to mention a waste of gas!!!

Any comments, opinions, or suggestions would be greatly appreciated!!!

Thanks!! default_smile

Regards,

timkedz

you are worried about nothing, as long as you shift when car is stationary, no damage

you are worried about nothing, as long as you shift when car is stationary, no damage

Not exactly. While you should never shift into park, reverse or drive while the car is moving, you also shouldn't shift it from park or neutral to drive or reverse while the engine is being revved above idle speed.

That being said, shifting the car at 1600 RPM is fine if that is what the car is idling at when you start it cold. If may be rough, but the transmission is designed to handle idle speed startup for all conditions.

Thanks, bhp02 and 99 Contour!!!!!

I kinda figured that it was okay to shift the car when cold, but, I wanted to make sure that I wasn't causing any premature/unnecessary wear to the transmission.

Just to play it safe, when it's cold outside, I still wait for a minute or two, before I start off when the car is cold. Initial idle speed is 2,000- 2,200 rpms. I don't think shifting at that speed is a good idea no matter what. The idle speed drops off pretty quickly from that point, usually within 15-20 seconds to around 1,800- 1,600 rpms. At that point, I feel that's a safe speed to shift.

I NEVER use the trans as a substitute for the brake; (i.e. when making a Y-turn and stopping the reverse motion by switching from reverse to drive, or vice-versa.)

Also, I don't believe in using the transmission as an engine brake, unless it was an emergency.

That being said, I think I am doing all the right things for my car to ensure it's long life.....

Thanks again, bhp and contour, for putting my mind at ease!!! I appreciate it!!!

Regards,

timkedz

Ok, since this topic came up, I'll pose a question. I read somewhere that turning OFF the overdrive when you know you won't be going over 45 mph will "reduce wear and tear" on your automatic transmission. I know zip about ATs and less about O/Ds. Is this true? There is a paragraph about it at Wikipedia.

http://en.wikipedia.org/wiki/Overdrive_%28mechanics%29

switch your gear when car is not moving meaning on brakes.

Ok, since this topic came up, I'll pose a question. I read somewhere that turning OFF the overdrive when you know you won't be going over 45 mph will "reduce wear and tear" on your automatic transmission. I know zip about ATs and less about O/Ds. Is this true? There is a paragraph about it at Wikipedia.

http://en.wikipedia.org/wiki/Overdrive_%28mechanics%29

I don't see how one could possibly argue that. Overdrive is basically an artificial 4th gear in the car, without actually having a physical 4th gear. Its electronic. As it states in wikipedia, it reduces your engine speed, which reduces wear on the engine.

 

Picture it like a bicycle. If you had a 3-speed bicycle, you can travel at higher speeds on each gear. Lets say gear 1 allows you to get to 7 mph before you start to reach your peak efficiency (the point at which you are spinning your pedals so fast that its inefficient to remain in that gear). At this point, you switch to gear 2. This allows you to get to 12 mph before hitting peak, then you switch into gear 3. Final gear in a bicycle allows you to go as fast as your bicycle's "engine" (meaning you) can go. Up to that point, your maximum potential is determined by the gearing, which is holding your power back for the need of torque to pull your bike. Now if you added an artificial 4th gear onto that bike, you will be shifting your bike earlier, thus not requiring you to rotate your pedals at higher rpms over longer periods of time and higher torque levels. Shifting to 2nd gear might hit around 5 mph, into 3rd at 9 mph, and final hits at 12 mph. The final gear is at the same time, but because you are shifting earlier, overall you aren't straining your engine (you) as hard to reach higher rpms. Your putting out more raw power (hp) for a particular rpm the sacrafice of lower torque (pulling power).

Basically what this translates to is extending your torque performance over a broader range. Another way to imagine this is if you started your bicycle off in a single gear. You have to put in so much more energy to get your bike moving because you are creating alot more torque (pulling power) at the wheels. Your wheels don't spin as fast, but put a lot more torque into the wheels, thus allowing you to moving more effectively in tougher situations. This is what happens on a car when you drive in L gear in the snow. The reason why you don't operate like this when its not snowing is because going back to the bicycle example, running on a single gear all the time will make your engine work unneccessarily harder and wasting energy and fuel for extra torque when you dont need it.

About the only 2 applications I can think of that would be benefitial for turning overdrive off is going up a mountain, or towing something heavy. By turning the o/d off, you will generally run at higher rpms and in a lower gear for longer periods of time (until you reach shifting speed). The thing is that usually in these 2 applications, you would set your car to "L" gear, rathere than turning off overdrive. Basically I would reccomend to everyone to leave overdrive on all the time.

You only turn overdrive off for two reasons and two reasons only:

1) You are towing a trailer, boat, etc.

2) You are driving on very hilly or mountainous roads and the transmission is shifting in and out of overdrive excessively.

In this case shifting excessively is defined as shifting to the point where your engine races, yet you can't keep a steady speed. This will happen on most cars while driving through the Rocky or Smoky mountains. Only cars with large V8 engines with big torque bands and smart transmissions can stay in its highest non overdrive gear on these type of roads. Even these cars benefit from turning overdrive off to eliminate the possibility of going into overdrive.

I would not put my car in L or 2nd to drive on hills, mountains or tow anything. L causes your engine to lag at higher speeds and wastes gas. Turning overdrive off is adequate to keep the car from racing the engine while slowing down, yet it still provides decent fuel economy and doesn't cause engine lag.

I shift my car to neutral while driving 75 MPH down a hill. I want to see how far it can go while rolling.

shifting an auto tranny while moving could be dangerous.

This is not a luxury performance vehicle. The auto was not designed for it.

Get a standard.

I shift my car to neutral while driving 75 MPH down a hill. I want to see how far it can go while rolling.

default_ohmy !! I hope you did this on a manual transmission. Doing that on an automatic is the perfect way to blow out your tranny.

 

 

Ok, since this topic came up, I'll pose a question. I read somewhere that turning OFF the overdrive when you know you won't be going over 45 mph will "reduce wear and tear" on your automatic transmission. I know zip about ATs and less about O/Ds. Is this true? There is a paragraph about it at Wikipedia.

http://en.wikipedia.org/wiki/Overdrive_%28mechanics%29

I don't see how one could possibly argue that. Overdrive is basically an artificial 4th gear in the car, without actually having a physical 4th gear. Its electronic. As it states in wikipedia, it reduces your engine speed, which reduces wear on the engine.

 

Picture it like a bicycle. If you had a 3-speed bicycle, you can travel at higher speeds on each gear. Lets say gear 1 allows you to get to 7 mph before you start to reach your peak efficiency (the point at which you are spinning your pedals so fast that its inefficient to remain in that gear). At this point, you switch to gear 2. This allows you to get to 12 mph before hitting peak, then you switch into gear 3. Final gear in a bicycle allows you to go as fast as your bicycle's "engine" (meaning you) can go. Up to that point, your maximum potential is determined by the gearing, which is holding your power back for the need of torque to pull your bike. Now if you added an artificial 4th gear onto that bike, you will be shifting your bike earlier, thus not requiring you to rotate your pedals at higher rpms over longer periods of time and higher torque levels. Shifting to 2nd gear might hit around 5 mph, into 3rd at 9 mph, and final hits at 12 mph. The final gear is at the same time, but because you are shifting earlier, overall you aren't straining your engine (you) as hard to reach higher rpms. Your putting out more raw power (hp) for a particular rpm the sacrafice of lower torque (pulling power).

Basically what this translates to is extending your torque performance over a broader range. Another way to imagine this is if you started your bicycle off in a single gear. You have to put in so much more energy to get your bike moving because you are creating alot more torque (pulling power) at the wheels. Your wheels don't spin as fast, but put a lot more torque into the wheels, thus allowing you to moving more effectively in tougher situations. This is what happens on a car when you drive in L gear in the snow. The reason why you don't operate like this when its not snowing is because going back to the bicycle example, running on a single gear all the time will make your engine work unneccessarily harder and wasting energy and fuel for extra torque when you dont need it.

About the only 2 applications I can think of that would be benefitial for turning overdrive off is going up a mountain, or towing something heavy. By turning the o/d off, you will generally run at higher rpms and in a lower gear for longer periods of time (until you reach shifting speed). The thing is that usually in these 2 applications, you would set your car to "L" gear, rathere than turning off overdrive. Basically I would reccomend to everyone to leave overdrive on all the time.

Without going too deep into Wiki, my understanding is -

There really is a 4th gear in our overdrive tranny. Turning off overdrive only tells the ECU to not shift into it, and downshift away from it if already in it. And that gear turns the output shaft faster than the input shaft, hence "over"-drive.

Higher the gear is at a given speed, slower the engine turns, less fuel and spark needed to keep it turning at that speed, hence better fuel economy.

When towing, keeping overdrive off means using a lower gear. In turn so that you don't fall out of your engine's power band, thereby relieving it from strain, while giving it the grunt needed to haul its ######, and what's hooked to its tail. default_biggrin

The bicycle example isn't really a good one. Because except for the lowest gears on a mountain bike, most (if not all) gears on a bicycle are overdrive. Because your legs can exert much more torque on the crank than needed to get the bike moving. I should know, because I have rode them for more than 14 years, and currently have 3.

i thought the word overdrive meant .................................

Sorry guys, i miss worded it. I meant the engine RPM < wheel RPM while in

drive mode.

Buurin pretty much quoted the definition of what overdrive means to me. But generally speaking, think of overdrive as the highest gear available in the transmission/transaxle.

OMG, sometimes I shift my auto Rolla into Neutral while going about 40mph downhills, just to roll (cuz its a rolla)... I never knew that was bad. I only shift back into drive when I have stopped though.

OMG, sometimes I shift my auto Rolla into Neutral while going about 40mph downhills, just to roll (cuz its a rolla)... I never knew that was bad. I only shift back into drive when I have stopped though.

 

I'm not a mechanic, but, I think the reason for that is when you are rolling in neutral, you are not properly lubricating the internal parts of the transmission/transaxle properly. I'm not sure if that applys to a car that is running and rolling while in neutral, BUT, I do know that if you roll, or tow a car that is NOT running in neutral for a significant distance, say several miles you will definitely ruin the transmission sometime soon in the future!! I learned that the hard way with an old Dodge Omni I owned several years ago!!

regards,

timkedz

I don't think average "coasting" distances will harm the transmission and I think your input on towing is correct. Most transmissions today have a front pump which is driven by the engine/torque converter/flex plate and supplies the fluid throughout the transmission.

Transmissions with rear pumps have been made in the past. These transmissions allowed push starting an automatic car at 20 or so MPH.

Some standard transmissions can be harmed similarly by towing long distances with the drive wheels on the ground. It is suggested that rear wheel drive cars have the driveshaft removed prior to long distance tows. 4WD vehicles should have the transfer case in neutral.

OMG, sometimes I shift my auto Rolla into Neutral while going about 40mph downhills, just to roll (cuz its a rolla)... I never knew that was bad. I only shift back into drive when I have stopped though.

 

I'm not a mechanic, but, I think the reason for that is when you are rolling in neutral, you are not properly lubricating the internal parts of the transmission/transaxle properly. I'm not sure if that applys to a car that is running and rolling while in neutral, BUT, I do know that if you roll, or tow a car that is NOT running in neutral for a significant distance, say several miles you will definitely ruin the transmission sometime soon in the future!! I learned that the hard way with an old Dodge Omni I owned several years ago!!

regards,

timkedz

I don't think average "coasting" distances will harm the transmission and I think your input on towing is correct. Most transmissions today have a front pump which is driven by the engine/torque converter/flex plate and supplies the fluid throughout the transmission.

Transmissions with rear pumps have been made in the past. These transmissions allowed push starting an automatic car at 20 or so MPH.

Some standard transmissions can be harmed similarly by towing long distances with the drive wheels on the ground. It is suggested that rear wheel drive cars have the driveshaft removed prior to long distance tows. 4WD vehicles should have the transfer case in neutral.

OMG, sometimes I shift my auto Rolla into Neutral while going about 40mph downhills, just to roll (cuz its a rolla)... I never knew that was bad. I only shift back into drive when I have stopped though.

 

I'm not a mechanic, but, I think the reason for that is when you are rolling in neutral, you are not properly lubricating the internal parts of the transmission/transaxle properly. I'm not sure if that applys to a car that is running and rolling while in neutral, BUT, I do know that if you roll, or tow a car that is NOT running in neutral for a significant distance, say several miles you will definitely ruin the transmission sometime soon in the future!! I learned that the hard way with an old Dodge Omni I owned several years ago!!

regards,

timkedz

This is slightly off-topic, but speaking of transfer cases... I was shoveling my driveway during the last snowstorm and witnessed a line of tow trucks with cars on them. Apparently they had all been parked durign the snow-ban, since they all had snow on them. Well, the last car in line was a jeep cherokee, being towed by the rear wheels (which is correct since it is rear-wheel drive). The problem is that since it was a snow storm, the owner had parked it in 4WD, and the front tires were litterally skidding along the (somewhat snowy) road. I felt sooooo bad for the owner of that SUV... can you say new tranny/transfer case/driveshafts/u-joints?

I felt sooooo bad for the owner of that SUV... can you say new tranny/transfer case/driveshafts/u-joints?

Not to mention the big fat flat spots on the tires? default_laugh