5 Things You Should Never Do In An Automatic Transmission Vehicle

5 Things You Should Never Do In An Automatic Transmission Vehicle

Hello everyone, and welcome! In this video we are going to be about five thing you should never do in an automatic transmission vehicle and this is a kind of follow up to the video I did of… Five things you should never do in manual transmission video and i think just as important is to understanding in what you shouldn’t be doing is understanding why? So I bought some parts along. This is a part of torque converter and so we’re going to be looking at, you know kind of how mechanically automatic transmission works So that we can better understand, why we shouldn’t do certain things in them… which I think is just as important as understand what you shouldn’t be doing. So the first one we’re going to be talking about is that you should never put your vehicle in neutral when you’re coasting down a hill. And so the logic behind this may be that, you know, you can save fuel economy by putting it in neutral and coasting down a hill. And let’s say you’re on a tall hill, and about to go on a shorter hill, If you put it in neutral, you can gain a lot of speed and gain enough speed to go over that smaller hill without, you know, getting on the gas and so you can save some fuel by doing that. But the other thing is, when you do have it in gear and you’re coasting down a hill modern transmissions and modern vechicles, what they’ll do is that they’ll cut fuel to the engine. So you’ll just use the wheels, which are connected to the transmission, and thus the engine. Because it’s in gear, to shut off the fuel injectors so that the wheels will be powering the engine. And so in that case you won’t be using any fuel. So as you’re going down that hill you won’t be using any fuel. And you can see this on fuel economy indicators If you put it on neutral, it’ll read something a little bit lower and then if you put it in drive, then you can notice the instantanious fuel economy will go up to the highest number that it can read. Because it has shut off fuel from going in to the engine. Now the other reason you don’t want to do this, and there is really three reasons. Is that it kind of takes a bit of control out of your vehicle. So when you’re in neutral, you only have the ability to slow your vehicle down. You no longer have the ability to speed up, because you’re not in gear. So you’re taking out part of your control from it. And the third reason, if those aren’t good enough for you to not put it in neutral when you’re coasting down hill. It is often illegal in states. So I started looking up the law in a bunch of different states, Not every state, but I found 15 states, and I will include links to all of these states’ laws in the video description. But there is a huge list of states, Arizona , California, Colorado, Deleware , Georgia, Illinois, Michigan and so on. 15 states which I found citable sources. You can go on these government websites and see the law where it says ‘Do not put it in neutral’, because you are taking yourself out of control of the vehicle. So, you know, if those aren’t good enough reasons, one and two then the third reason, it might be illegal where you live. So you know, look up your local laws, to figure that part out. But regardless, it could be illegal where you live. Moving on to number two, whenever you’re changing directions in an automatic transmission vehicle, you wanna make sure to come to a stop before switching from drive to reverse, or from reverse to drive. So backing up, come to a stop, then put it in drive, and then move along. And so the reason why you want to do this is because, you’re using your brakes to stop the vehicle rather than your transmission. Your transmission is designed to shift gears, your brakes on the other hand are designed to stop the vehicle. So this is an automatic transmission band, and what this does is is it clamps down around the housing of a planetary gear set. And when you do that, you alter the gearing of the planetary gear. So when you’re in reverse or drive this might be open, and then when you put it another one it’ll clamp down on a drum. So this works a lot like a the reverse of a drum brake. So instead of pressing out like a drum brake, this squeezes down on a drum. And so, what you’re doing when you change that direction is you’ll be using these bands, as well as clutches. Automatic transmissions also have multi-plate clutches within them And so when you switch gears, these bands will clamp down to change the gearing And when it does that, you’re using this material here on this automatic transmission band to stop your car, rather than the brakes, which are easy to service and cheap to replace. Versus this part which was only $18 but very difficult to access. Which is going to take you a lot of time to replace it, or a very expensive repair. So come to a stop, then put it in what gear you in to go in. Number three we’re going to talk about launching your car. Now obviously, if you want your car to last as long as possible, and you want the maximum longevity out of your transmission, then you should never launch the vehicle. It is going to put a lot of strain and stress on it. But there’s different methods I’ve seen people use, and some of them are kind of, you know are kind of dangerous and you should never do them. So one of the methods I’ve seen that people have done is they’ll rev it up in neutral and then they’ll drop it into drive and then let that carry their car forward. And so that’s kind of a dangerous way of launching your vehicle…. and we’re going to get into why using some parts. So here we have a torque converter, and this is the pump, or the impeller, and so what you’re going to have is the engine which is going to be connected to a flex plate, and that flex plate is going to be connected to this. So this has been cut off, so that we can see the inside of this torque converter, but know that this is always going to be rotating with the engine. So this is the pump, or you could call it the impeller, and within this we have the stator which we’ll go ahead and set aside… and what that does is it reverses the direction of the fluid, when it’s transferring between one side from the pump to the turbine. And so here we have the turbine, and so you can see an internal spline, there, and so this is what’s going to be rotating with the transmission. So this will be splined with the transmission as the impeller rotates, it will force this turbine to rotate, and as the turbine rotates, it will rotate the transmission, and thus the wheels. So this is a fluid coupling, and so what that allows you to do is have a difference in speed between your transmission and your engine. So your engine can be rotating and your transmission can stay stationary, as I’m demonstrating here. So this is connected with the flex plate, and as that rotates, you can see the transmission can be held still. So when you’re at a stop, that’s what will be happening this will be rotating, and the turbine will just be stationary, because it’s connected to your wheels, which are not moving. When you launch and you rev it up in neutral, and then you put it into drive what you’re doing is you’re going to be having friction between this, this band… and the drum which it’s resting around, as that tries to clamp down to send power through it. And so, you’re going to have clutches and bands within your automatic transmission that are going to try to be absorbing that power, but you’re going to have slip, because you’re sending so much power through it, and these are designed to shift gears, not to handle a launch. And so you’re sending power through it, and you’re going to be wearing out this band… as I mentioned, it’s going to be very expensive to replace it. So rather than putting it in neutral, revving it up, and then putting it in drive, which is just kind of crazy, what you want to do is put your foot on the brake, and put your foot on the gas, build up some pressure within this torque converter, so you’re putting a lot of torque to that impeller… or, to that turbine which is stationary, and then the second you let off the brake, you’re sending all the torque, and all of your clutches and bands are already locked up in the position they need to be, so you’re not going to have any slip. Now, yes, you’re going to put a lot of strain on your transmission, and it’s not like a great thing to do for it, but it’s a lot less dangerous than putting it in neutral revving it up and then putting it into drive, and then letting the clutches and bands handle all that torque, and trying to get power to the wheels and spin your tires, rather than spin these bands, which will be very expensive to replace. Moving on to number four… there’s no reason to put your car in neutral when you’re sitting at a stop light. It’s fine to leave it in drive, and that’s something some people will commonly do is to take it out of drive. For several reasons they may think, okay, it’s putting a lot of stress on your transmission. But, let’s think about that for a moment. If you’re sitting there with it in drive, so your engine is spinning, and my hand, which is touching the turbine, obviously isn’t moving. So your engine is spinning, [the turbine] isn’t, so you’re putting some stress on the transmission. And yes, that’s absolutely true, you are doing that, but let’s think about it. Once you let off the brake and you start accelerating, you’re putting a far greater force into that turbine to move your vehicle forward than if you’re just sitting there with your engine idling and it’s trying to put some of that energy into the turbine. So really, you’re not putting any additional stress on it, it’s far less than you are when you’re actually accelerating, so it’s kind of crazy to think, “Oh, I shouldn’t do that.” The second thing some people will say, it can save fuel economy. And when you are in drive, obviously you’re going to be putting some of that energy into trying to rotate this, and you’re rotating against an object which is stationary, whereas if you put it in neutral, it can spin much easier because you’re disconnecting from the transmission. Well, the thing is there, you will tend to idle higher in neutral verses being in drive, but regardless it’s not going to be a big fuel economy difference. I actually had a Volvo in which gave a live readout of your fuel economy while you’re sitting there at a stop light and it said it was using 0.3 gallons per hour. So, if you think that you’re just going to sit at a stop light for, let’s say, 30 seconds, you do the math, that’s 0.0025 gallons to sit there at that stop light with it in drive… as I had it in that Volvo with the live readout. So, you’re not really going to be using that much fuel. Now if you’re sitting in stop-and-go traffic, there’s a ton of cars, you’re surrounded, so there’s no need to get out of an emergency situation or anything like that really quickly …and you’re just stuck, you’re stopped in traffic, and you want to make sure that you’re going to get maximum fuel economy, just turn your car off. If you’re just going to be sitting there, there’s cars all around you and it’s a safe time to do it, turn your car off and just let it sit there so you’re not using any fuel. Like, that’s the easy solution to saving fuel if that’s the reason why you put it in neutral from drive. And then the other thing switching from neutral to drive, you might think, oh, there’s going to be less wear, things like that. And you are going to be using these bands as you switch from neutral to drive to clamp down on the transmission. Either way, it’s not going to be a lot of wear because your vehicle isn’t moving and there’s not a whole lot of energy being put into that transmission. So, I wouldn’t really worry about wear of doing it from neutral to drive, but there’s really just no good reason to take it out of drive. Just leave it in drive while you’re sitting there at the stop light, and you’re not putting any additional wear, and you’re not really going to be saving any fuel. Moving on to number five, you should never put your vehicle into park until you’ve come to a complete stop. So, you should never put it into park while the vehicle is moving. Now, here’s the thing. Most automatic transmissions, especially modern ones, will not allow you to do this, but it’s cool to understand why. When you put your vehicle in park, you’re applying a pawl, essentially a locking pin, into a gear which is connected to your transmission’s output shaft. Your driven wheels are connected to the transmission output shaft, so when this is locked, your wheels cannot move. Now, if you were to engage the parking pin while the vehicle is moving, and there weren’t systems to prevent this from happening, you could very easily shear the locking pin and break it, as it attempts to completely lock up a transmission in motion. Either way, you’d be putting a huge amount of stress into your drivetrain and transmission. Now, I can’t really think of any scenarios where you might think it’s a good idea while you’re moving to put it in park, but let’s say you’re trying to come to a stop, and you can’t really figure out how. You’ve got acceleration happening and you can’t prevent it; you’re throttle is stuck for some reason. The first thing you should do is firmly press your brakes. Your brakes are always going to be able to out-power your engine. Now, you may use up that vacuum assist, and so because of that you may need to press really hard in order to get the brakes to successfully work, because once you run out of brake assist from the vacuum pump and you’ve got full throttle, you’re going to lose that assist. And so, you want to make sure you press that firmly. It may not seem like it’s working because you don’t have brake assist. You’ve got to push really firm. The other thing you can do is downshift. So, as you downshift, you’ll start to slow the vehicle down, and so that’s another method of bringing your vehicle to a stop. So, thank you guys for watching. If you have any questions or comments, feel free to leave those below. So I have this Peruvian mango box which I was using to store the torque converter in. Who knew there were so many ways to eat a mango? You can eat it on a fork, cut the skin and peel it and, there you go, eat it on a fork. You can slice ’em, you can dice ’em, or you can eat it with a spoon. Amazing! Mango, such a versatile fruit, to get your vitamin C on.

About the Author: Michael Flood


  1. 2 things, mate. Why don't you use your garage for the presentations, I feel like you shouldn't be parked on some road talking to the camera, you do this in several videos, you do edit anyway. And, your counter arguments on "saving" fuel and other stuff when at a stop are sound, but, do you step on the breaks the whole 40-60 seconds of the red light…?

  2. I put it in neutral when I'm sliding up to a stop on black ice. It helps to keep me out of the intersection.

  3. I don't get why people coast It will save you pennies if much. btw costing it's very doable with manual transmission. I don't do it I want to be able to hold my current speed without having to ride the brakes.

  4. If you have a cool sounding car and your in a light stop would you rather rev the engine while it's in neutral or parking? Which is better

  5. That means every BMW with the ZF in eco-pro is illegal in those states since in eco-pro it’ll disengage and let the car coast.

  6. Dear engineering explained. i do like your videos, but i have to say that this one have got some errors. First, a volvo you were referring to(or most volvos these days) uses a GM auto box, thus it has this feature. While you applying the foot brake, It selects neutral when the car is standing still for more than three seconds.The moment you let go of the foot brake or step on the accelerator, the forward clutch engages. You can feel it, because if you sometimes catch it of guard, while applying the brake and gas at the same time, the car will momentarily rev up before the forward clutch engages. Secondly, it's not to reduce wear and tear on the gearbox but to save fuel and reduce emissions.

    Other GM products that does the same are Opels(most of the world), Vauxhalls(England), Holdens(Australia) and Chevrolet( USA and so fourth).
    I first experienced this feature when i serviced a 2005 Opel Safira(4 speed auto with overdrive).

    Yours Sincerely

  7. If the roads are slippery due to snow or ice you DO want to shift into neutral before coming to a stop, especially in a rear wheel drive car. If you don't you're in danger of locking up the non-drive wheels before the drive wheels come to a stop, potentially pushing you into the intersection, possibly with your front wheels locked up with no steering control.

  8. I drive a taxi in Las Vegas and you could ask 100 cab drivers what the "B" is for on their Prius trans shifter and you'll get 100 drivers that don't know that it's for down-hill engine braking.

  9. He says that less fuel is used when in gear than neutral. My tach says differently. When in gear and foot off of accelerator, rpms around 1200. When in neutral it's around 900. I get the part about control. And re against the law? how are cops gonna know you're in neutral? It's not like a light comes on when you do. Someone told me it's not good mechanically so I was looking for a mechanical reason not to do it.

  10. 3 years later…. cut fuel to the engine? My 2007 corolla has a damn trans-brake and down shifts going down a hill if i have to apply the brakes. Shift into neutral FTW while braking.

  11. Several modern vehicles decouple the transmission when you sit at idle at traffic lights, pressing the throttle pedal re-engages the transmission.

  12. What about when you start your car back up after turning it off in traffic? Does that use gas starting back up?? Would it be better to just leave the car on rather than shutting it off to save gas? Would you lose more gas starting it back up VS leaving it on

  13. As a teenager I drove my moms 5.0 Mustang GT a lot and I would take it to my High School Parking lot at night with my buddies and we would neutral drop that thing and launch it, do burn outs, you name it. Rev it up to red line and slam it into drive. Yea never realized how bad that was for the tranny and luckily it held up. My mom ended up crashing the stang years after I graduated from high school and moved out and it still had the Original Automatic Transmission.

  14. Very Interesting ! Most usefull hint for ordinary drivers is nr4, on 7:15 , I agree. Still , newbie vintage cars collectors when acquire 51 Buicks or Chevys with Dynaflow or Powerglide, start with "L" even on flat streets to "help" the motors, what I think is wrong, incurring on what you said above. I have two friends who do that. Thanks Jason for your very clear and didactical video,

  15. Can you do one for towing with an automatic transmission? Is  it better to be in drive or 3rd gear when towing a load and do trailer brakes help save the transmission?

  16. Thanks for the effort you put in on this video. I’m uk and not everyone would understand this let alone understand a manual car. Automatic transmissions are a thing of beauty these days and should be understood. Tough to get a lux car without one and in uk a lot of drivers don’t get the transition or nuances. Great video and top effort.

  17. I had a Lincoln whose data center allowed instantaneous Now fuel mpg. I used to speed up just before a hill put auto trans in neutral and view just how high my instantaneous fuel miles per gallon would get. Highest I ever got it was in the 70's mpg. Does this mean I will be visited by the Coasting Police? It was over 10 years ago; Texas has a 6 year Staute of Limitations…guess Im safe.
    Edit: Confession Time
    I also run thru the house w/scissors in my hands; Doh, are the Scissor Police on their way now?
    Edit: Confession Feels Good
    I also ripped the tag off my mattress…no reason, I just felt like it: the rush of addrenaline was off the charts. Are the Mattress Police on their way also. What can I say Im a rebel w/out a cause, a bad seed. Are there any 12 step programs for someone like me?

  18. He goes on in another video and says when you’re stopping for a long time put it in neutral because your car’s transmission is in stress well I call BS on his channel he says things and contradicts them a lot

  19. Now, I know to stop the car with the brakes, but I pull out of driveway backing up a hill, is it still bad to shift into neutral, let the car stop, and then start rolling forward and then put it in drive while rolling forward? I feel like it's less stress on the Transmission. @Engineering Explained I hope you see this, i've been meaning to ask this for a while.

  20. The corollary to the last point (should have been the main point) is that you should always use the parking brake when parked – using the parking pawl alone (especially on even the slightest hill) to keep the car from moving puts unnecessary strain on the transmission

  21. Me and my buddy used to 'hyper-mile' in his old 1990 Vanagon. "Slip it into neutch" we called it. We also shut off the engine to maximize economy. I have no idea why the cooling system kept springing leaks in various locations 😀 😀 😀

  22. Bit late question, but was told to use the hand brake after parking the car and turning it off so the car is not resting on the transmission

  23. I always drove manual cars but my 08 get unfortunately is auto. So my question is. Can I switch to manual mode while driving or do I have to be at a dead stop?

  24. good day,i'm danny from the philippines,i would like to ask why i can't put to PARK the automatic transmission of my 2013 Chevrolet ? the car is okey,in fact i use it everyday,it runs forward when i put it to Drive, it backs up when i put to Reverse, it just would not engage to Park, i am now using the manual parking brake whenever i park the car, is there something wrong with the transmission?…

  25. One reason I like to put my auto in neutral is that the pulling at the stop light annoys me. I've always driven manuals so I'm not used to the pulling effect. I also want to preserve my brake lights by not holding them on for a minute. What do you think about these reasons?

  26. When my car is idle feels like engine is shaking like when I stop for red light and if keep it on D the car mildly shakes but if i put it in N its quite again. Any idea why??


  28. Im driving my car, my speed is about 100km/h, then i switch to "R" because i thought it is for "Rocket" hahahaha lol



  30. I had to use park to stop once… On a cold morning I was about to leave the gated apartment complex. When I was nearing the closed gate (where you have to stop) suddenly the brakes wouldn’t do anything . So I quickly pulled the handbrake and put the car in park out of desperation 😬

    Somehow afterwards the brakes worked just fine…

  31. That's not how torque converters work m8. The outer shells are welded together, THEY reverse the flow of fluid TO the stator thus spinning it which is connected to the input shaft and the trans pump which generates the hydraulic pressures needed to engage the various bands and clutches.

  32. The best is when people go to McDonald's drive through and shut off their engines to save gas but refuse to walk their fat asses inside.

  33. I'm no engineer, but please enlighten me as to the correct procedure when approaching a RED. At the moment, I step off the gas, go to neutral, and then when stationary engage Park. Is this or is this not the optimal approach?

  34. Sir drive CVT automatic transmission car can I apply neutral gear when I am at traffic signal when it is red please reply sir

  35. that 4 one made me wonder, why is there a parking mode at all? logically manual vehicles don't have it and they just put it on neutral and use the hand brake, so why do automatic cars have it if you can select neutral and apply the handbrake the same way as with manual cars?

  36. Never let your automatic car run down a hill in neutral to jump start it … when you pick up enough speed and slam it into gear the car is broken 😎😎😎 and your battery is still dead

  37. When I'm driving on the freeway and I wanted to go faster FAST, I would step off my gas and shift to D3 from D (Honda Civic 2012 coupe), will that damage the transmission if I do that then GAS it??

  38. I have a 2003 Corolla with 280000 miles on it. I always put it neutral going down hills. Only had to change the brake pads once. Never had a transmission problem. I live on dirt roads.

  39. God forbid the owner's manual made it that easy. Gave me 4 sets of instructions. Tried each one. No go.
    Thanks for the video.

  40. Is it okay for an automatic DCT to engine brake? Lets say im going downhill and i put it in 2nd gear. Will it damage/prematurely wear anything?

  41. I drive a 2017 Ford Mondeo (Fusion) with automatic gearbox. When I have to stop for a short period (red lights, traffic jams) I leave the transmission in D and pull the electronic handbrake on. The handbrake then automatically disengages when accelerating, very handy…. If I park the car on a slight incline does it suffice to leave the transmission in D or do I always need to apply the handbrake ?

  42. I had my brakes go out on a vehicle while I was driving in Germany. Trust me, using the hand brake to stop the vehicle doesn't make for a very smooth stop. It just locked up the tires and I went sliding for a very long distance… and I wasn't going but maybe 35 mph. I didn't just yank the thing either… I pulled up on it nice and slow. And like the diagram shows, it's all or nothing pretty much. Went from no braking to full on locked up wheels. It was an old vehicle but I suspect modern ones would do the same thing. It stopped me, but I slid at least 3 or 4 times further than had I used no skidding normal braking. It was rather scary.

  43. Hi. I have a 2004 chevy Corvette. I have it with a 4 speed automatic transmission. I like to manually shift it. Like I always put it in 1 and
    Go back and forth between 1-3 as a would drive a stick shift, and use D for highways. Will this hurt the car when manually shift it all the time? Thank you. Best Regards Lasse.

  44. 1. Your argument about fuel economy is flawed. Yes, the engine burns more fuel in idle, but most automatics have a free-wheeling clutch so it's idling down the hill anyways. If you're in tow mode or downshifted so you're no longer freewheeling, you're slowing the car down via intake vacuum to keep the engine turning, which robs you of speed at the bottom of the hill. You then have to speed up by the amount you lost, which likely requires more fuel than you saved by not idling down the hill.

    2 and 3. The clutches inside the transmission have to slip while changing gears all the time. Occasionally putting extra wear on them isn't going to have noticeable effects on longevity. At least on some cars, neutral dropping gives much better launch performance than stalling the torque converter. So if your goal is speed, that's what you're going to do regardless of extra wear.

    4. I put automatics into neutral while stopped because it's much easier to slightly hold the brake to keep from rolling than moderately holding the brake to keep the engine at bay. Some transmissions won't even move until you give it throttle, while others require a lot of brake pressure to hold still, so this is context-dependent.

    5. Probably good advice, but generally the pin is just going to rat-tat-tat like accidentally shoving a manual towards reverse instead of fifth when they put reverse where seventh would be. It shouldn't damage anything, especially at low speeds where there's not that much pressure to begin with (that pin is designed to hold the car's weight on a steep hill). That said, I did hear a story (second-hand) about a guy who shoved it into park at like 40 mph and it exploded his transmission all over the highway, so that might be an issue. And it's uncomfortably shocking for passengers when the transmission stops the car instantaneously from 3 mph.

  45. What will happen if the gear is moved to reverse when the vehicle is on the road with the speed of 100 miles per hour??

  46. Hi, how bad is it if I accidentally put the car in Neutral while driving and then put it back in Drive again while going about 25-30mph ? I heard a slight "thud" sound .. nothing crazy but it bugs me!

  47. I was about to park my SUV and I accidentally put my gear to drive instead of park. Is that bad? How will it affect transmission?

  48. Best way to brake downhill is to spin the car 180 so you are reversing at 100 kmh+ then put it at 5k rpm+ it and dump into 2nd this way you wheelspin in the opposing direction for max force in the opposite direction. Eventually the tyres will burst for max grip. I would say 1st gear but. I am unsure with thinner tyres that the wheel speed is fast enough.

  49. I have an example where you might want to put the transmission in park while moving. Two, actually. The first one, I picked up my truck from the mechanic, started driving home and the throttle stuck wide open. I couldn't switch the key to the off position when it was in gear, so jammed the brakes on hard and came to pretty close to a stop then switched to park ( easier to find than neutral) and turned off the ignition before the rpm ran away. So just sort of, not really.
    The one that was a perfect example, driving a loaded truck down a steep grade and the brakes failed completely, not fade, just completely gone. Master cylinder I think. So with the transmission in reverse apply throttle to slow the descent, if the engine stalls slam it in park before it picks up speed. Gravel roads so if it's too much torque it slips the wheels a bit. Also in the middle of nowhere, so no mechanics, no parts, no tools, no communications, you have to get it done or walk. Similar situation when a fuel pump stopped working, used some insulator from electrical conduit, pulled the conductors out and used the tube to siphon from a small can of gas on the roof directly into the carb.

  50. Jace Henderson  breaking while in neutral is not efficient u are only uaing brakes at that time, but breaking while in gear either auto or manual is efficient as your engine is also helping to slow down
    jut try to stop a car without using brakes in gear and in nutral ur car will stop sooner as compared to that in nuetral, REMEMBER THAT EVERY SECOND IS IMPORTANT

  51. Never shift into reverse on the highway…… Not even with a rental, in Florida, on spring break, with your drunk buddies……

    How does your car work with all those parts missing……..

  52. Now is 2019 and many cars coast in neutral at motorway speeds to save fuel. Even the new 911 does it. Less RPM means less fuel loss, if you are not using any fuel it doesn’t necessary mean that you are going more efficient.

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