Braking problem

Discussion in 'Gen 3 Prius Main Forum' started by eglmainz, Jun 22, 2009.

  1. F8L

    F8L Protecting Habitat & AG Lands

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    You must be more clear with your language. Does the car actually speed up without you touching the brakes or gas pedal or are you in the process of braking and the car temporarily reduces the speed at which it is slowing down? There is a big difference between the two and you make it sound like you are driving along and the car suddenly speeds up when you hit a manhole. :)
     
  2. GreenGuy33

    GreenGuy33 Active Member

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    I hope that the recall will fix my braking problem when I hit a pothole or sewer cover. It has happened a number of times to me when I press the brake pedal and go over a bump, the car will feel like it is accelerating (may be just losing my brakes for a moment). It is scary for that brief moment.
     
  3. gbarry

    gbarry Junior Member

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    Are you going downhill at the time? The cruise control uses regenerative braking to keep you from speeding up. Releasing it allows you to "coast". The reverse is true going uphill, although that's more obvious to people.
     
  4. dogllama

    dogllama New Member

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    I have experienced the "surge" while braking over a pot hole several times here in Los Angeles.

    I just got off the phone with Toyota of Santa Monica and they told me there is no firmware update available as of now, and also said that their new cars are not running updated firmware either.
     
  5. ddurbin

    ddurbin New Member

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    I am a reporter with The Associated Press based in Detroit. We are interested in talking with 2010 Prius owners who have experienced the braking problem, for a story we are doing today in advance of tomorrow's expected recall. Please email me if you are interested in talking about this issue. My email is [email protected]. Thank you very much.
     
  6. horsehead

    horsehead New Member

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    It happened to me once. I was coming upon a huge dip at an intersection. I knew I needed to slow down, or bottom out. I hit the brake, the car did not slow down but rather felt like it accelerated first and then barely slowed down in time to avoid bottoming out. Felt my stomach drop as it happened. Scared me and by the looks of the faces on people walking on the side of the street, it scared them too.
     
  7. Canard

    Canard Member

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    You know...

    I can't help but draw a parallel with this "surge" phenominon and a similar situation that "occurs" (but really doesn't) in the 450-series (Old) smart fortwo sold in Canada.

    The transmission in the smart in question is an AMT (automated manual), so you have to manually effect gear changes by pushing a lever either forward or pulling it backward. When you do that, the car cuts engine power, opens the clutch, shifts gears electrically, closes the clutch, and resumes the power flow as per your pedal position.

    A lot of people early on were all up in arms thinking there was a mysterous "7th gear" or a surge of power if you pushed "+" (shift up) while already in 6th. But really, all it is, is the human mind getting confused. If you think you're in 5th (but are realy in 6th), and push up, you expect the loss of power, shift, and resumption of power... but it never happens. So what you feel is a sustained non-loss of power, but your body is already flexing up preparing for the deceleration asscociated with a shift.

    Even further to prove this, if you already know you're in 6th (by looking at the dash) and pushing up, you "feel" nothing. Your passenger never feels it, becasue they didn't know you tried to fake-shift. The only time it's ever felt is if you do a blind shift and think you're in 5th (but aren't).

    About 50% of people on the forums "get this" and the other 50% continue to insist there's a mysterious feature (that only happens sometime) that magically finds more power in the tiny 40 hp engine and blasts you along. :)

    I think this surging people are feeling is not at all a "surge", but in fact is just a slightly-less agressive braking occuring, one that is not in line with the body/mind's expected outcome based on pedal input.

    -Iain
     
  8. Tideland Prius

    Tideland Prius Moderator of the North
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    Well a situation happened yesterday which I can only describe as "I think this is what everyone else is talking about with regards to the braking issue." Let me explain. I am aware of the manhole cover/railway track braking/slipping scenario. It has happened on the Gen 2 many times that I've grown accustomed to releasing the brake pedal as I approach and then re-applying the brakes afterwards.

    Yesterday was the first time I've experienced it in the Gen 3 and it wasn't a manhole cover or a railway track.

    I was approaching an intersection with the intention of making a left turn. This intersection had a left turn bay, separated from the general flow of traffic. Unfortunately, with all the melting of the snow and the fluctuations in temperatures above/below freezing, the city roads have developed a LOT of potholes, and given the type of vehicles here (mostly fullsize pickups), some of the potholes are fairly large.

    I pulled into the left turn bay and began braking. There was oncoming traffic so I had full intentions to come to a complete stop. I noticed just ahead of the white stop lines that the pavement was a bit dark (Note that it was also night time) but I figured it was just rough pavement as opposed to potholes. As I continued braking, crossing the white lines and ended up in one of those potholes and the car "surged" as the others describe. Now, the car probably didn't but that was the sensation. I now understand when others here have posted that it felt like the car went another foot before braking power resumed. It sure felt that way. Unfortunately, the car went on to hit another larger hole and I ended up hitting the front bumper on the pavement before coming to a full stop. I don't think I sustained any front bumper damage (I haven't look at the car in daylight yet) but as you can imagine, it was a rather interesting series of events in that intersection.

    Would I say it was an issue? I don't know. There wasn't a car in front of me to gauge whether I would've hit him or not. I was more pissed that I scraped the bottom of the bumper driving over a pothole. (It was a loud bang from inside the car). But now I have a better understanding of that sensation that others have described.
     
  9. Pretext

    Pretext New Member

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    Yep, the car simply floats over a bump when you are braking. Not a good feeling, I would think this is a major safety issue that needs attention from Toyota. How can you simply hit the brake harder when the tire is not in contact with the ground, it simply like the brake lets go. Also the car surges in park when the engine starts, I've had the car travel 2-3 feet when I had or thought I had the brake fully engaged. Seems that a thread with this many pages is reason enough to declare a safety issue and a recall.
     
  10. mfa-prius

    mfa-prius Old member

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    Indeed. I haven't had a real breathtaking event yet, (just an occasional "Oh, Sxxx, there it is again!" :eek:), but I imagine it's only a matter of time. The real problem is that you can't really tell when it's going to happen. It isn't always potholes, manhole covers, or railroad tracks -- a minor irregularity in normal pavement will sometimes trigger it.

    Moral: Whenever you're braking, leave a little extra room.
     
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