Poll: Are Prius brakes a problem?

[bwilson4web]

A few new data points:







There were a few reports that I was not able to find via Google 'street view.' I'll take 10-15 minutes but I can't post what I can't find.

Bob Wilson

[bwilson4web]

Originally Posted by duraace

That may be the cause. I wonder if there is a solution? If the regen braking goes off, shouldn't it make a smooth simultaneous transition to the regular brakes? The car really lurches forward when it hits this spot. It might cause someone not expecting it to overreact in some hazardous way.

This remains an interesting question. When we test drove a 2001 Prius with less than 100 miles on the clock in 2001, I could detect the regen transition just under 5 mph at stops. But by 2005 when I picked up our 2003 Prius, I couldn't detect it in a car with 49,000 miles.

I've never felt the regen transition with out 2010 (ZVW30) Prius. As for the braking anomaly, I've found one pot hole that has a momentary, very fleeting, effect that I can detect but not quantify. In fact, if it weren't for the braking threads, I wouldn't have even noticed it. I continue to try and replicate the symptoms.

Without some way for everyone to be able to replicate the problem, it remains an 'intermittent' problem. These are maddening to address because the engineering team (even NHTSA) can't apply normal engineering practices to diagnose it. "Shouting" is not a symptom ... it takes rubber on road.

So far, all of the reports are beyond my day-trip comfort zone. So far, I've not been able to find a road rough enough with the right pattern to replicate anything but a momentary, fleeting impression. I'm not doubting the reports of others but reporting I can't replicate it, yet.

Bob Wilson

[mbarrows]

Originally Posted by bwilson4web

This remains an interesting question. When we test drove a 2001 Prius with less than 100 miles on the clock in 2001, I could detect the regen transition just under 5 mph at stops. But by 2005 when I picked up our 2003 Prius, I couldn't detect it in a car with 49,000 miles.

I've never felt the regen transition with out 2010 (ZVW30) Prius. As for the braking anomaly, I've found one pot hole that has a momentary, very fleeting, effect that I can detect but not quantify. In fact, if it weren't for the braking threads, I wouldn't have even noticed it. I continue to try and replicate the symptoms.

Without some way for everyone to be able to replicate the problem, it remains an 'intermittent' problem. These are maddening to address because the engineering team (even NHTSA) can't apply normal engineering practices to diagnose it. "Shouting" is not a symptom ... it takes rubber on road.

So far, all of the reports are beyond my day-trip comfort zone. So far, I've not been able to find a road rough enough with the right pattern to replicate anything but a momentary, fleeting impression. I'm not doubting the reports of others but reporting I can't replicate it, yet.

Bob Wilson

Bob,

I agree with everything you said above (except the part about a G2 Prius not having a lapse of regenerative breaking under 5 MPH - my wife and I both have felt this on occaision in our 2005 when we had it) as I've only had one experience in our new 2010 that I think is even close to what others are saying and for me it was a non-event. I'm going to keep trying to get the car to do this when I drive it (usually on weekends).

Mike

[enigmaticfox]

Originally Posted by TonyPSchaefer

In my opinion, most of the people complaining about this are those who practice "free-fall breaking" in which they wait until the last second to break and pray nothing goes wrong. Most who coast to stops (or coast to avoid stopping) and break long and slowly rarely encounter it.

I'm coming in a little late to the discussion, but I don't think this is always the case. I practice extremely conservative driving, slowly coasting to long stops, and I have also experienced this sudden loss of braking while going over a bump. In my case, I was coming down a neighborhood steep hill (slowly) and doing my usual long slow braking for the intersection at the bottom. About 10 ft from the bottom of the hill and the intersection, there was a sudden sharp bump from a pothole, and abruptly my brakes weren't braking any more.

I was able to regain braking control by releasing the brake entirely and then slamming back down on the brakes again, but it was quite startling, and I'm just glad that I figured it out in time to miss sliding out into the intersection!

Take care,

--Sherri, otherwise happy 2010 Prius owner

[bwilson4web]

Hi Sherri,

Nice first post:

Originally Posted by enigmaticfox

I'm coming in a little late to the discussion, but I don't think this is always the case. I practice extremely conservative driving, slowly coasting to long stops, and I have also experienced this sudden loss of braking while going over a bump. In my case, I was coming down a neighborhood steep hill (slowly) and doing my usual long slow braking for the intersection at the bottom. About 10 ft from the bottom of the hill and the intersection, there was a sudden sharp bump from a pothole, and abruptly my brakes weren't braking any more.

I was able to regain braking control by releasing the brake entirely and then slamming back down on the brakes again, but it was quite startling, and I'm just glad that I figured it out in time to miss sliding out into the intersection!

Take care,

--Sherri, otherwise happy 2010 Prius owner

By now I hope you've seen Toyota is planning to distribute a fix. My suggestion is to document where you've seen the problem; test that it is still there before getting the fix; and testing it after the fix is in. I've been collecting Google and Google Street View and photos of places where this happens:

We've got over 20 and counting locations and images. If you want to add one or more that would be good with me.

Thanks,
Bob Wilson

[hitechboy]

Its happen to me 3 times only over the 5 months that I owned the car. 1 of them was quite scary on the highway.

To reproduce the problem, you have to travel at a constant speed not too slow and the brake have to be applied slightly and continuely (Slowly slowing down). There must be another car closely in front of you in order get the out of control feel. When you go over the potholes your car will lost the brake for a split second and you will feel like you dat forward and going to hit the car in front.

[hybriddriveguy]

I will say after working in the auto repair industry for over 30 years that new technology is always un-nerving for consumers and technicians.
When ABS brakes were first introduced in the US, we had a constant stream of customers, who did not trust their dealer when they were told the brake pedal was supposed to push back at them and they shouldn't be able to lock up the brakes. We spent many hours of our time re-educating our customer to trust the technology. Since the late 70s, ABS feel has changed very little from one make to the next, even though the methods have varried greatly.
When I first began studying the Gen3 Prius, I was immediately impressed that someone was finally trying to do away with all the noise and pedal pulsing associated with an ABS system, but I also thought, "here we go again" on re-educating our customers. We have talked to many since the news media and our government has taken aim at Toyota and not one has failed to stop their car as expected.
I think the sensation of feeling like the car is not doing anything creates an immediate sense of panic, but is probably not causing the vehicle to stop any slower than it could normally.
With the old system, the solenoids would immediately give you feedback in the pedal that something was happening before the brake pads were engaged, but we have lost that feedback with the new design.
I think this is a good thing, but it will certainly take some getting used to.

I am also concerned greatly with the level of attacks being leveled at Toyota given the scale of their failures and their quick response. Are we trying to "level the playing field" a little?
GM had a big problem with brakes on their front wheel drive cars starting in 1980 that would cause the rear to lock up and send the car into a skid. This continued to be a problem for at least 10 years, even though there had been many accidents and deaths associated with the failures. During that time, the media and the government were pretty quiet about it.
I guess we lived in a different world then, but it is food for thought.

This is just my opinion and I am not trying to dismiss or disrespect anyone over this issue.

[scottle]

Has anyone tried replicating this scenario but not changing the pedal position when it happens. Both times that it's happened to me instaict takes over and I hit the pedal hard. It would be interesting to see what happens if the driver didn't do this, would the brakes still reapply???

[qbee42]

Originally Posted by hybriddriveguy

I will say after working in the auto repair industry for over 30 years that new technology is always un-nerving for consumers and technicians.
<snip>

Thanks, hybriddriveguy. I think your post provides a lot of needed perspective. Our world has become more polarized, and less tolerant to anything not perfect. Many of us now think that we live in a theme park where everything is clean, safe, and beautiful. My wife and I see this all of the time with sailing and rock climbing. There are a lot of people who think that the government should control the weather and make sure that rocks don't fall. Life just isn't that clean or easy. Hopefully we all do our best, and try to do the right thing, but at the end of the day a lot of s__t happens.

There are some bad apples; people and companies that try to cheat. They deserve to get smacked. However, for the rest, we need a little more tolerance and a whole lot less hysteria.

Tom

[enigmaticfox]

Originally Posted by bwilson4web

Hi Sherri,

Nice first post:

By now I hope you've seen Toyota is planning to distribute a fix. My suggestion is to document where you've seen the problem; test that it is still there before getting the fix; and testing it after the fix is in. I've been collecting Google and Google Street View and photos of places where this happens:
(sherri edit: image snipped because I don't have permission to post links yet)
We've got over 20 and counting locations and images. If you want to add one or more that would be good with me.

Thanks,
Bob Wilson

Hi Bob,

Yep, I realized after posting and then reading the entire thread that I'd jumped the gun a bit (as well as bringing back a mostly dead thread...sorry about that, all). What a first impression to make! Thanks for being understanding despite my newbieness.

I will have to see if the pothole/bump is still there; this happened months ago, and I really just chalked it up at the time to "interesting albeit spooky Prius quirk" and have just been watchful since then. It was only yesterday when I started reading about the investigation that I said "Oh wow, that sounds exactly like what happened to me!" and decided to go to PriusChat to see if others had seen it too. I didn't realize that it was such a polarizing topic!

Trust me, I'm not a Toyota or a Prius hater. I love my 2010! Makes our summer drive to North Carolina from snowy New England more fun again. I do wish that this investigation didn't hit at the same time as their other massive recalls, Toyota is going through a very hard time right now.

Take care,

--Sherri