CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Gear Change in an Automatic Transmission Car

Hi Guys,
A quick question, can one change gear in an automatic transmission car while driving? i.e. say it is in D and you are driving and you want to shift to either gear 2 or 1, can it be done without stopping the car? If yes, then how does one go about it? Thanks for your help and time.
Warm Regards
Shri

First, you need to consult your Owner’s Manual, which should tell you the maximum safe speed in each gear position for your mystery vehicle.

Once you determine the maximum safe speed in each gear, then–yes–you can feel free to downshift when you come to a steep upgrade or downgrade. Just bear in mind that you should do it sequentially.

Don’t go directly from D to 1, unless you are going VERY slowly.
Instead, go from D to the next lower gear (5, or 4, or 3, depending on the vehicle) and if this does not produce the desired effect, then you can downshift to the next lower gear. If you are now going very slowly and still need a lower gear, then you can downshift to 1.

Just to add to what VDCdriver mentioned. Most automatics made in the last 15-20 years are electronically controlled, and have buit in safegaurds to keep the engine from overspeeding should you manually downshift. For examply if you going along at 60 MPH and you drop the gear selector into 1st. The transmission will only drop to 2nd gear, but will drop to 1st gear only when you slow down to a low enough speed to where the engine won’t exceed redline should in 1st gear.

Yes, you can shift forward gears while the car is moving. You don’t want to shift into R while moving forward. Cars have different shifters so you should experiment at first with the car sitting still. If you put the shifter in D, then push it towards R it should not go into R, rather it should move to N. You have to push on a button to move past N to R in most cars. Once you see you can’t move past N to R then you should be able to move from D to 3, 2, or 1 and move the shifter back to D with no problems.

Now get the car rolling and at about 40 mph move the shifter from D to 3 and see what happens.

If you’re going down a long steep hill, you definitely should be shifting into a gear that helps to keep your speed under control, so that your brakes don’t overheat and fail. That’s the main reason why this feature is there.

As others have said, the transmission should prevent you from shifting into a gear that would damage the engine, but it’s still best to have some idea of which gears are inappropriate for your current speed and avoid using those, just to be safe.

Please tell us why/when/what conditions are when you want to shift manually.

How long have you been driving? Is this your first automatic?

If it’s a late model car, not only can you downshift, but the computer that controls the tranny won’t allow you to damage it. You have protection. The computer knows how fast you’re going (from the VSS signal).

By the way, I downshift very often. If I’m on a road where traffic is doing 40mph I figure it saves the wear of the tranny constandly shifting back & forth as I go over the inclines and declines.

I’M WITH @thesame. Not only can you do it, but according to the manual, you are encouraged to do for safety and proper driving. Many new gate shifters actually “encourage” you to do it while driving. Heck, the computer shifts it all the time. Why should HAL have all the freak’n fun.

What a heck, just buy a car with manual transmission…

Some drivers like to preserve that left foot freedom for tapping to the music from their car stereo.

Thanks Guys. I apologize for not mentioning about my car and the genesis of this question. I have been driving an automatic close to 15 years now (10 in the USA and 5 in India). I am in India now and own a Hyundai Santro (2006) automatic transmission and the manual does not mention anything about shifting the gear while the car is running (Nissan Sentra (USA) manual had info about this). I never tried it though. On a family trip, upon encountering a very steep slope, I stopped and shifted to lower gear (1). So, my daughter asked about changing the gear without stopping the car and I was not very sure, hence the question. I will try sometime this weekend shifting from D to a lower gear (either 2 or 1) while keeping the speed under 40kph. Do I need to push the button to shift?
Once again thanks for your time.
Warm regards
Shri

You may or may not need to push a button on the shifter, it depends on the car.