1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Is shifting to neutral at red lights bad for transmission

Discussion in 'Prius c Main Forum' started by kalsifur, Aug 6, 2014.

  1. kalsifur

    kalsifur Junior Member

    Joined:
    Aug 6, 2014
    7
    1
    0
    Location:
    New York City, New York
    Vehicle:
    2014 Prius c
    Model:
    One
    I shift to neutral when approaching a red light when my speed is exactly at 7 mph to save on battery power that would otherwise continue to propel the car forward. Combined with proper timing, this also allows my car to come to a complete stop without the use of brakes on flat roads. Once stopped, I immediately shift back to drive to allow the battery to charge if needed and of course in preparation for the green light.

    A few sites, such as Putting your car in neutral at read lights. Good or bad? (red light, manual transmission) - Automotive -Sports cars, sedans, coupes, SUVs, trucks, motorcycles, tickets, dealers, repairs, gasoline, drivers... - City-Data Forum mention that shifting from drive to neutral at red lights, then back to drive again when the lights turn green puts wear on automatic transmissions.

    Given that the Prius C has CVT, will it also wear, due to such frequent D -> N -> D shifting under the circumstances described?
     
  2. ftl

    ftl Explicator

    Joined:
    Jun 2, 2009
    1,812
    790
    0
    Location:
    Long Island NY
    Vehicle:
    2012 Prius c
    Model:
    Three
  3. kalsifur

    kalsifur Junior Member

    Joined:
    Aug 6, 2014
    7
    1
    0
    Location:
    New York City, New York
    Vehicle:
    2014 Prius c
    Model:
    One
    Thanks. That thread mentions two things:

    1. That shifting to neutral is a bad idea because regenerative braking cannot be used
    2. No harm is done to the transmission in the process

    (2) answers my question.

    As for (1), I don't shift to neutral when speeds are above 7 mph. Approaching a red light, my foot is not on the brake or gas pedal and regenerative braking slows my car sufficiently to 7 mph (the speed at which regenerative braking is no longer available and battery power starts to be used to creep the car forward), at which point I shift to neutral to save on the power used for creeping, and so that the car then slows to 0 mph without the use of the brake pedal. Then I shift back to drive. The total time in neutral is typically 10 to 20 seconds, which is negligible when considering battery discharge.

    You can see the transition from regenerative braking to the use of battery power for creeping on the HSI at 7 mph: the bit of blue in the regenerative braking region disappears, and a bit of green appears in the ECO region. Then, when in neutral, the green disappears.
     
    #3 kalsifur, Aug 6, 2014
    Last edited: Aug 6, 2014
  4. JimboPalmer

    JimboPalmer Tsar of all the Rushers

    Joined:
    Apr 14, 2009
    12,470
    6,862
    2
    Location:
    Greenwood MS USA
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    Useless but harmless. You may not be cheating yourself out of MPGs but that is not what you asked.
     
  5. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,571
    48,862
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    i do the same thing. my father taught me to drive like that (what if you have a heart attack at a red light and the car rolls forward and hits somebody?:eek:) and i can't break the habit.:cool:
     
  6. robertmaria

    robertmaria Member

    Joined:
    Mar 28, 2014
    202
    41
    0
    Location:
    please DELETE this account
    Vehicle:
    2014 Prius c
    Model:
    One
    years of riding Harleys has taught me to always be in gear at anytime on the road, even at red lights. and the same habit for me driving any cars too. i can hear that distinctive click as calipers lock with the ensuing swish of silent skidding to my side rear or behind and then I gas it to save my assets,,, pure instinct,,, sorry, i have never heard of using neutral,,,
    ~~ worse case scenario is "sorry officer, i ran the red light because in heard a swish sound"
    ~~~~ what actually has happened i heard the click and then a swishing sound , so i gunned my bike right thru the intersection ,,, it saved the cop's life because as he looked up to see me loud as hell go past him and his outstretched hand right behind me was the old man in the dodge dart still skidding (towards the cop who assumed everyone had stopped),,, no way will i ever put my car/bike in neutral. (and thankfully the cop was ok and the construction workers too).
    ~~ drive safe. always keep your control of your vehicle. ride safe.
     
    #6 robertmaria, Aug 7, 2014
    Last edited: Oct 17, 2014
    ewaboy, HiC, kevtan and 4 others like this.
  7. citroenjohn

    citroenjohn Active Member

    Joined:
    Mar 26, 2013
    139
    103
    0
    Location:
    Mid-Michigan
    Vehicle:
    2013 Prius c
    Model:
    Two
    This is only my opinion, but, if you're in neutral and on the road you don't have full control of the vehicle. If for some reason you had to accelerate out of a situation and were in neutral you would have to identify the problem, react to it , and then put the car into gear before you could accelerate. All of the time used up before you can accelerate is time that might prevent you from avoiding a situation. Granted it might be only a fraction of a second, but, it might be what was needed. The only time I would consider taking my car out of gear is if I were on black ice and engine braking was causing the car to go into a slide that could not be controlled, but, then again I use very aggressive snow tires so hopefully this is not likely to happen.
     
  8. straw10

    straw10 New Member

    Joined:
    Oct 16, 2014
    5
    0
    0
    Location:
    Wallingford, CT
    Vehicle:
    2012 Prius c
    Model:
    Two
    I'm glad I'm checking all the forums...was just going to ask the same question.
     
  9. GrumpyCabbie

    GrumpyCabbie Senior Member

    Joined:
    Dec 14, 2009
    6,722
    2,120
    45
    Location:
    North Yorkshire, UK
    Vehicle:
    2010 Prius
    Model:
    III
    What if your HV battery is low because you've been stuck in heavy traffic for 20 minutes and have your a/c on high because it's a hot day, you then stop at a Red and slip into Neutral. Your car can't attempt to charge the HV battery if it gets too low and this could cause issues with fuel economy at the very least and possible damage to the HV battery as well as the car refusing to start?

    Happy to stand corrected.
     
  10. JimboPalmer

    JimboPalmer Tsar of all the Rushers

    Joined:
    Apr 14, 2009
    12,470
    6,862
    2
    Location:
    Greenwood MS USA
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    All of that is true, and I think it is senseless, but the question was is shifting to neutral harmful to the car and it isn't. It will lower your MPG, but that is not the question.
     
  11. PriusGuy32

    PriusGuy32 Prius Driver Extraordinaire

    Joined:
    Sep 10, 2012
    1,411
    506
    0
    Location:
    Harrison Township, Michigan
    Vehicle:
    2015 Prius
    Model:
    Four
    The practical side of me wonders about all of the extra wear and tear on the shifter assy itself, and on the diodes/capacitors/transaxle/MG's for doing this.

    The Prius is such an intelligently designed car, I see no need to shift to neutral when coasting. Let it do its thing on its own.
     
    defrankond likes this.
  12. tpenny67

    tpenny67 Active Member

    Joined:
    Jun 14, 2014
    464
    402
    0
    Location:
    Massachusetts, USA
    Vehicle:
    2014 Prius
    Model:
    Two
    I'm with kalsifur on this. Using N below 7 mph seems to make sense sometimes. I do it when I'm creeping downhill in traffic, and think it's silly that the car us using the battery to creep the car downhill while the friction brakes are engaged. It's the same situation that I'm in neutral with a manual transmission because I'm not going fast enough to fully let the clutch out in first gear.

    There's no wear issue with the motors or electronics because the electricity is normally being switched on and off thousands of times per second, and N simply keeps all the switches "off".
     
  13. GrumpyCabbie

    GrumpyCabbie Senior Member

    Joined:
    Dec 14, 2009
    6,722
    2,120
    45
    Location:
    North Yorkshire, UK
    Vehicle:
    2010 Prius
    Model:
    III
    I know it's your car and you're happy switching into Neutral and I understand why, but surely any slight benefit you gain from doing this is immediately wiped out 3 seconds after you start up your Mustang.
     
    ztanos, tpenny67 and PriusGuy32 like this.
  14. tpenny67

    tpenny67 Active Member

    Joined:
    Jun 14, 2014
    464
    402
    0
    Location:
    Massachusetts, USA
    Vehicle:
    2014 Prius
    Model:
    Two
    The benefits are entirely psychological :)
     
  15. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    54,470
    38,103
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    With our previous Civic hybrid with it's traditional CVT (if that makes sense) I'd frequently push into neutral, for rolling to reds and while stopped. The car would typically auto-stop once warmed, but when it was running and stopped, neutral really smoothed it out. With the conventional shifter it was much easier to shift.

    With the Prius though, I put it in drive, never touch it again.
     
  16. robertmaria

    robertmaria Member

    Joined:
    Mar 28, 2014
    202
    41
    0
    Location:
    please DELETE this account
    Vehicle:
    2014 Prius c
    Model:
    One
    i didnt realize the Prius shifter was so very different from the more traditional shifter on the c. now i can understand why the concerns about neutral and park.
     
  17. mahout

    mahout Active Member

    Joined:
    Nov 29, 2010
    655
    116
    0
    Location:
    NC
    Vehicle:
    2012 Prius c
    Model:
    Two
    I'm curious why you let off the brake once the car is doing less than 7 mph; I can see no benefit whatsoever. My car if I released the brake would roll for a considerable bit. Besides, the electrical feedback continues til the car stops so rolling the last 7 mph does nothing except extend the stopping distance.. Its harmless I agree unless you think throwing away the last bits of regeneration is bad.
     
  18. GrumpyCabbie

    GrumpyCabbie Senior Member

    Joined:
    Dec 14, 2009
    6,722
    2,120
    45
    Location:
    North Yorkshire, UK
    Vehicle:
    2010 Prius
    Model:
    III
    I'm guessing they do it because there is no regen below 7 mph.

    Why they bother is certainly questionable and I just couldn't be bothered with that sort of OCD shenanigans, but it's their car so I guess they do what they like.
     
  19. tpenny67

    tpenny67 Active Member

    Joined:
    Jun 14, 2014
    464
    402
    0
    Location:
    Massachusetts, USA
    Vehicle:
    2014 Prius
    Model:
    Two
    Note that below 7mph the car switches from regen to creeping (using the battery to power the car against the friction brakes), and sometimes that seems totally ludicrous, like when stuck in traffic inching down a hill. Yes it is OCD, but it also gives me something to do when I can only drive three car lengths each light cycle.

    Speaking of using neutral downhill, a few decades ago I had a 4-speed Chevette, no power steering or brakes, that would regularly stall when coming to a stop at this particular intersection. Only a few cars would get through each time the light turned green, so I'd leave the car stalled and just coast down the hill a few car lengths at a time, then restart at the bottom of the hill (many times while coasting with the clutch in) and drive off. Back then I didn't even know that was called hypermiling :)
     
    ztanos and Mendel Leisk like this.
  20. JimboPalmer

    JimboPalmer Tsar of all the Rushers

    Joined:
    Apr 14, 2009
    12,470
    6,862
    2
    Location:
    Greenwood MS USA
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    The real reason we are having this conversation.
     
    ztanos and tpenny67 like this.