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Temporary brake loss over bumps

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by MrMischief, May 31, 2016.

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  1. Weasle543

    Weasle543 Member

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    The Gen 4 has a traction control off button. Left of the steering column next to the instrument cluster dimmer rocker switch.

    See owners manual Pg 406
     
    #21 Weasle543, May 31, 2016
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  2. MrMischief

    MrMischief Active Member

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    The vehicle I got rid of to make room for the Prius was a Jeep Commander with Quadra Drive II, quite possibly the best AWD system ever made IMO. It features a true full time 48/52 split with the ability to send 100% of the power to either axle or lock to a 50/50 split. Within the axles there are limited-slip differentials that feature electronically controlled mechanical lockers to force the wheels on either side to turn at the same speed. People talk about the ability for traction control systems to move power from left to right, but really it is just increasing the amount of torque required to spin the slipping wheel in the hopes that the torque on the gripping wheel becomes great enough to move the car, (torque is always equal between two wheels on an axle. Traction control is a much less capable system than lockers, but it can be more predictable on the road and is much lighter weight. While tires are a huge factor vehicle hardware and software also play a big role in modern cars. Coming from QDII to a Prius, "how the car does in snow" is a very legitimate question. The Commander never required dedicated snow tires because I ran BFG T/A KO2s, an all-terrain tire that carries the mountain/snowflake symbol and is rated superior in snow and excellent on ice. The only thing that ever stopped that Jeep was the sight of a gas station. It seems that the Prius will, although honestly I'm thinking I may skip the snow tires and just go straight to snow socks
     
    #22 MrMischief, Jun 1, 2016
  3. eric1234

    eric1234 Active Member

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    Well, I think that comparing an all wheel drive vehicle to a front wheel drive vehicle is a bit inapplicable.

    But within vehicle types I do understand and agree that variation in traction control systems (hardware and software) would provide different results. For example a traction control system that applies the brake to a spinning wheel will yield a different result than the traction control system that merely reduces engine output.

    The former increases the amount of torque provided to equal that available to the wheel most capable of transmitting the torque. The latter decreases the amount of torque provided to equal that available to the wheel least capable of transmitting torque.

    In either case, increasing the amount of friction between the vehicle and the road (i.e. selection of a good winter tire) will ultimately increase the amount of torque transmitted to the road.

    Taken to an extreme - put bald tires on the Jeep Commander, and the hardware just isn't going to make up for the lack of friction (and thus, torque transmission capability) created between those bald tires and the road.
     
    #23 eric1234, Jun 1, 2016
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  4. DonDNH

    DonDNH Senior Member

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    I've been driving my Prii in the snow for 12 winters (an '04 and now a '10). I can attest that my wife's Jetta and Mazda were worse at handling even a small amount of snow. I run Blizzak snows on all 4 wheels and have never gotten even close to being stuck. Drivability is good as the car tracks well in a couple of inches of slush and traction control works at controlling wheel spin.
     
    #24 DonDNH, Jun 1, 2016
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  5. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    A couple things:
    1. The loss of braking is - as has been described - the system losing traction and releasing the brakes for a moment. In the past, people have referenced it as a "lunge" or that the car "jerks forward" but this is incorrect. The momentary loss of braking only feels like a lunge from inside the car. From outside the car, it is a moment of same-speed sandwiched between two spans of deceleration.
    2. After 12 winters in my Prius, I have encountered exactly one situation in which the wheels lost traction and I was stuck. I shouldn't have been out in the snow that day and seriously doubt any of my previous cars would have fared any better. I know many Canadian owners who swear by their Prius in the snow.
     
    #25 TonyPSchaefer, Jun 2, 2016
  6. ETP

    ETP 2021 Prime(Limit),Highlander HYB Plat,B52-D,G,F,H

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    I use to live in the great white north on active duty. Yes to snow tires in some locations. Front wheel drive does very well on ice and snow as well as plastic chains.
    Big hit to MPG but who cares eh!

    I have had the car skip sideways on a pothole road with too much air in the tires. Never do 51PSI anymore as 42 is the ultimate answer to all questions in the universe. You may want to go to 36PSI in the snow and ice and maybe 34???????

    Great thread as I did not know about the braking issue.
     
    #26 ETP, Jun 3, 2016
  7. Eva Anna

    Eva Anna New Member

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    Is there breaking problems like this with the 2016 Prius?
     
    #27 Eva Anna, Jun 6, 2016
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  8. ETP

    ETP 2021 Prime(Limit),Highlander HYB Plat,B52-D,G,F,H

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    Indeed, question of the day.:)
     
    #28 ETP, Jun 7, 2016
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