Got into an accident today due to brake problem =(

First, let me say that I'm sorry for your damaged Prius, but you're unhurt, that's a lot more important. Furthermore, you - and us - can learn a lesson from your accident. What lesson? IMO, that the Prius is not a normal car. You can drive it like a normal car, but, in order to obtain the best performances, even in terms of stopping distances on uneven surfaces, one has to learn how, experimenting it in safe conditions (e.g. in empty parking lots). And to be consequently prepared, when the unforeseen event happens, to obtain the best possible braking from the Prius.
About the effectiveness of the brake firmware update, a popular car's Italian magazine (Quattroruote) tested the Prius Gen III before and after the above update application. Here the results:

Furthermore, they stressed the Prius brake system carrying out more than a thousand emergency brakes. Their final judgment was "the Prius brakes pedal gives to the driver a strange feeling, but the braking itself is effective." (my translation may differ from the original, but i believe that the meaning is correct). And "Quattroruote" is not at all fond of Japan carmakers, believe me. They rather prefer German carmakers..

 

Last time I checked, the car has four wheel disc brakes. And yes they do work, as indicated by my rotors. I am sorry, but you guys need to stop with your hypermilling BS and just drive it like a normal car.

In many cases, I think a VP of common sense would help a lot of these people out.

 

And why is that data relevant? I've only experienced the problem at under about 15-30 mph, during normal braking. I've never had a problem at highway speeds or while using the friction brakes. The problem is with the handoff from regenerative to friction braking, at least that's how I see it.

Me? A hypermiller? Sorry, but that's just too funny. I'm one of the fastest drivers on the road, whether in my Cobra or my Prius!!! I just don't wait until the last second to slam on my brakes at a red light. That would be a sign of poor driving skills. Instead, I anticipate needing to stop at the light and apply my brakes accordingly. The cars then do what they do.

 

Perhaps that is the solution to the problem. If we did it that way we would bypass the regen and presto, no more problem.

 

As long as we could still complain about our brake pads and rotors needing to be replaced earlier than we were led to believe....

 

I've had my '06 for 4yrs. I use the brakes just like I did all my other cars. I've made gradual stops, abrupt stops, panic (max brake pressure) stops---with no problems whatsoever.

 

Ecobroker and all,

Here's a hypothesis that has nothing to do with the Prius-ness of your car, and a lot to do with its post-1990-ness:

You drove at a normal speed on the exit ramp.
However, when you braked on the rough/gravelly surface, you braked hard enough to engage ABS. ABS did what it always does: brakes, lets go (giving a lurching feeling), brakes . . ..
Because of the way it works, it lengthens the stop.

I have to say that I ALWAYS get that funny feeling you report whenever I brake hard enough on gravel or snow to engage ABS.

The problem is, we don't realize the way ABS feels and works because 1) it is advertised to us as though it makes you stop faster (which it doesn't--just more in control) and 2) we don't "try it out" enough to get a good feel for the way it works.

Ecobroker--does that make sense as a possible explanation?

The lesson I take away from this would be to slow down a bit more on rough/gravelly roads, even if you have ABS. Especially if you have ABS.

 

If there are no privacy issues, if you could post a Google Street View link to the location, that'd be great. Bwilson4web likes collecting those.

No, seriously... if I happen to be near it, I'd be curious to take my 2nd gen over it to see if it's repro as I have no consistent repro location in WA state. I've got one that I've posted earlier that's in Sunnyvale, CA.

Also, some Toyota folks do monitor PC and might be interested in the data point.

 

Paul,

A couple of things here upon which I want to expand:

(1) ABS looks at one thing: the rotational speed differential amongst the four tires. If the system sees one tire start to slow faster than the others, the system will assume that wheel is beginning to lock up and the system will pulse the brake pressure on that wheel only in order to keep it rotating and able to build cornering force.

(2) Because of this, ABS can't tell the difference between an icy patch, gravel or a manhole cover. All it knows is that one wheel is spinning slower than the others and it needs to intervene.

(3) ABS functions solely through the hydraulic braking system. Therefore, under full REGEN braking, should the system find a rotational speed difference, it has to do a full hand-off from the REGEN to the hydraulic system. It is this handoff the campaign is attempting to address.

(4) ABS will never help you stop faster. ABS will not create traction where there is none. ABS is designed to take full advantage of whatever traction is available and to allow you to steer around an obstacle. Perhaps a better way to describe the system would be anti-lock steering system, but nice person doesn't look good as an acronym.

(5) It is actually possible to lock up an ABS system. If all four wheels slow at the same rate, the system will not intervene (it's designed to look at differences in speed, not the rate at which the vehicle is slowing down).

So, having said this, if the change in coefficient of friction between the tarmac and the manhole cover is sufficient to cause a wheel to slow down faster than the other three while under full REGEN braking, then the handoff will occur.

QFT.

They're not taking a nap, they're handing off the baton -- something which, by design, never occurs in a non-hybrid. (See #2 above.)

 

Don't wreck the messenger! I once had a Ford F-150 and the torsion bar broke while it was sitting in the driveway. I went onto a Ford F-150 website and posted on the board and was immediately blamed and eventually I ended up kicked off the board and the problem was never resolved. There were numerous complaints about the torsion bars breaking yet there was never even a TSB. I complained to Ford and even threatened to throw the old bar through their headquarters front window to no resolution. Ford eventually dropped the torsion bar and went back to coil springs. This accident sounds legit and scary!

 

You are correct on both counts. The accident legitimately happened -- I believe the car was in an accident. And, accidents typically tend to be scary.

 

EcoBroker,

One other question. I had asked at the beginning of this thread:

There has been a lot of discourse since page 1, but after a quick re-read, I don't see where you'd answered my enquiry. Please advise.

 

Here you go:
Google Maps

Heading South on Locust just as you come into that sharp right-hand turn is where the sunken manhole cover is located (you can see it clearly if you street view the turn looking south).

 

Am I the Paul you're talking to? I'm honestly unsure what you're asking. "campaign"?

 

Forgive me -- I was still on my first diet Pepsi. I actually meant my question to the Original Poster. My mistake!

 

We basicly had the same debate about "The Braking Problem" before the software update. With basicly the same arguements. With those that have "never experienced it"--with those that have, but think it's acceptable and simply part of owning a Hybrid. And those that have experienced it and had a problem.

Clearly on Gen 3, I heard how it WASN'T a problem and then Toyota themselves implemented a software update to the entire line on the assembly line...then offered a recall.

My feeling, and it's only a feeling...not based on experience...but my feeling is that we can debate forever...because to an extent everyone's experience is correct. I think you can own a Prius, and maybe your driving conditions and style could lead you to drive for years without really experiencing the sensation. Conversely, I think more agressive drivers, or 1st time Hybrid owners are more likely to notice the difference...or it could be as simple as living in an area with more or less improved roadways. In anycase, those that claim to have never experienced it? While I believe you, it doesn't mean it isn't happening and it doesn't even mean it won't happen to you someday.

After reading numerous accounts and numerous threads I believe it's primarily the nature of the beast. I think it's a combination of a system that employs numerous tools to stop the vehicle, including all of them, friction, regenerative and stability control.

Is it a flaw? Well it depends on how you want to look at it. Seems a majority of experienced Prius drivers are willing to say it's something they are aware of and can adapt their driving and braking approach to accomadate.

I can't offer a specific opinion on this aspect because I don't own a Prius.

But to discount all other opinions and accounts from people, just because you have personally decided that A: It doesn't really happen OR B: It happens but is minimal and within the scope of "Normal" Hybrid Braking...isn't really fair.

Even for the original OP, whom seemingly loved his Prius and scoffed at reports of braking problems....it isn't a problem for anyone until the day comes when you aren't looking ahead, when you aren't prepared and for whatever reason you need to brake quickly on less than an ideal surface and you end up with a automobile that isn't responding to almost subconcious automatic expectations.

Can this happen with any automobile? Certainly. Bad road conditions, and ABS and other factors influence all automobiles, but I think there is evidence enough that given the addition of stability control and regenerative braking...it is more problematic for Prius drivers, especially first time drivers of the system that are lullled into complacency by a system that responds "normally" most of the time.

The truth is, Toyota might have to go back to the drawing board and work on improving the consistency of brake feel and reaction...because that's not an unreasonable expectation for owners to have, especially as Regenrative Braking and Hybrids become more and more mainstream.

The other truth is, the system as it exists, might not technically be flawed, or broken...just different enough to sometimes be dangerous.

 

Your experience was very similar to ours. We are not Toyota bashers (have owned them for 42 consecutive years) After a low speed brake failure on a smooth dry road which resulted in a crash, and $5000 damage to our car and total write off of the other car, we would not drive the car again (2009 with 16000 KM). We took it to the dealer who was most helpful. 5 hours and $1500 later the dealer owned the Prius and we owned a 2008 camry with only hydraulic brakes. We had excellent insurance with no prior claims. Therefore $500 deductible and minimal increase in insurance.

I now realize that trying to convince most people on this board that the Prius has a brake problem is a waste of time. However I think you should report your accident to NHTSA .

 

That's right. You are so great that you are complaining about pedal feel and the lack of rear brakes...

 

We've all experienced the brake problem but some of us are not aggressive drivers who blame Toyota after causing an accident. The Prius drivers here tailgate other cars and drive extremely close to other cars.....of course they will rear end the other car and then blame it on a non-existing brake problem.

The ramp has a exit lane...the OP was traveling 40mph close to the stop point, I bet 100% this guy was speeding on the exit lane and used regenerative brakes until the very last moment where he slammed the brakes well past the stop point. Easy to blame toyota. They want Toyota to fix the damage.

When I first got my Prius, I noticed that the brakes were very different and that you really did need to have enough distance to stop. Just today, I almost hit another car because I hit the brakes too late going downhill. This is purely driver error, not toyota.

 

I agree with your description of the problem. But neither of our analogies are really correct.

When a baton is passed, it never stops. The idea is for the second runner to get up to speed before receiving the baton from the first runner, who doesn't stop until the baton is passed. Losing brakes for ~1/2 second would be the equivalent of the first runner stopping and waiting for the second runner to catch up. The flaw is in handling that handoff, which apparently other hybrids can handle.

Where do you get that? I have never complained about "pedal feel" or lack of rear brakes. I have complained about the lack of any brakes during the handoff period.

Again, most people can probably train themselves to adapt once they've experienced the failure. But the first time it happens is quite a shock -- the sudden lose of deceleration really does feel like acceleration -- and I can see the OP or someone else getting into an accident because of it.

I just think Toyota designed the handoff poorly and that it should be transparent to the driver.