Anonymous asked in Cars & TransportationOther - Cars & Transportation · 8 months ago

Automatic Transmission ?

Dumb question, I've always wondered if it's okay to upshift from 3rd gear to 4th or downshift while driving in an automatic?

6 Answers

  • Edna
    Lv 7
    8 months ago

    What is there about the word 'automatic' in automatic transmission that you don't understand?

  • 8 months ago

    It's OK when needed, but the transmission upshifts by itself. You cannot make it upshift until it is supposed to. Downshifting might be handy to regulate your coasting speed downhill, or making speed control easier on winding hills. You should take care to not over rev the engine in any gear.

  • 8 months ago

    When you select a gear in an automatic transmission you aren't forcing the transmission into that gear, you're just telling the transmission control module the highest gear you want it to use.

    As an example, I have a van with a 6 speed automatic transmission (6 forward gear ratios). For normal driving I just put the shifter to "D" and the computer shifts between those 6 gears as needed.

    If I go into manual mode and select 4th gear, then the computer still controls which gear it will use at any given time, but it won't go higher than 4th gear. So it will still use 1st gear when I'm starting out from a stop, and up-shift at the appropriate time until I get to 4th gear. But it won't go into 5th or 6th gear. If I keep trying to accelerate it will just rev the engine higher and eventually I'll hit a top speed where the engine can't run any faster (the onboard computer won't let me rev the engine too high).The computer is smart enough not to downshift while you're moving too fast for the lower gear. So lets say I'm driving down an open highway going 80 mph and I go to manual mode and select 2nd gear. The computer is not going to instantly shift into 2nd gear. It will try to downshift one gear at a time without redlining the engine. So as soon as my speed is low enough that it can safely go from 6th to 5th, it will downshift to 5th and won't let it go back up to 6th. Then it will look for a chance to downshift to 4th, and then 3rd and so on, until it gets to the gear I wanted.

    But the computer is basically idiot-proof, its not going to let you go into a gear ratio at a speed that's going to cause damage to the engine or transmission.

  • 8 months ago

    It is OK as long as you don't rev the engine.

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  • 8 months ago

    I do it all the time on my 2000 Bonneville SSEi.

    I watch the tachometer and don't downshift when the rpms are higher than 2,800 rpms.

    Most newer vehicles have rev protection built into the PCM.

    Source(s): Mitsubishi Master Tech
  • Anonymous
    8 months ago

    Automatic transmission only has 4 basic gears:

    Park, reverse, Neutral, Drive

    Most automatic cars have an additional S-Gear which has a lower gear ratio designed for going uphill or through lots of twisted turns.

    They also have the B-Gear which has a low gear ratio but is designed differently. This is suited for slowly coasting downhill.

    The ones that do have numbers can allow you to upshift and downshift BUT automatic cars are not designed to change gears often based on speed(manual), the different options are mostly for different terrain.

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