Poll: Are Prius brakes a problem?

There is major street repair being done on my route to and from work and almost everywhere I go. It has been totally torn up and repaired but there are some major bumps and a huge pothole. When I hit the pothole that is when I experience what I call the weird feeling which I guess is the brake/traction. It does not seem to make me lurch ahead or make it take longer to brake. It just "feels" strange. It only happens when I am going in one direction and this is the only place it happens. It really is a huge hole in what is not even a piece of paved street. I can't wait for them to fix it and then I am sure that they slight change I feel will go away. I find the brakes on my Prius to be the best brakes I have ever had in a car. When I need them they are there and they are firm and stop the car without any sway whatsoever. and they are fast. I am delighted with my Prius and do not regret my purchase. It was bought in late Sept, but I am not sure of the manufacture date. I will say that my cargo net was correctly installed so it had to have been made after that issue was discovered and corrected.

Thanks for the poll- Great idea.

 

It took me 2 1/2 years to experience the problem. I've encountered it about twice since then - over a 5 month period. It is definitely a scary experience the first time. I'm on the fence as to whether it's a safety issue or not. In my situation, I've only encountered it during speeds under 35 MPH and not with a critical consequence looming.

Regardless, brakes shouldn't stop braking when you're applying the brake pedal.

 

I have a place where I could consistently make it happen that is right around the corner from where I live. Now that I have replaced the OEM tires, it isn't consistent anymore. In any event, it is no big deal and I think it is just a quirk of the Prius brake system.

 

I chose scary, safety issue but I wish there was a scary, _potential_ safety issue option. I've read the thread and for me it comes down to what ibmindless said. Brakes should keep braking, period, even during transition from regen to friction.

Bob, there is a rough patch near my home where I was able to recreate it when I tried last week. I may go over there tomorrow with a camera and then try it repeatedly and see how many times it happens out of 5 or 10 tries.

I agree with an earlier poster that it should be investigated, and it may be determined that it does not increase braking distance, and if that is the case AND there is no way to get rid of that loss of braking sensation, so be it.

Again, I want the Prius to be wildly successful but this issue can only hurt Toyota, the Prius, and hybrids in general.

I read some posts where the driver was unsure if they had experienced this. If you are unsure if you have experienced this issue, there is no question that you have not. You will know it when it happens!

 

This^^^^

This is probably why I've never experienced anything like this sensation in 4 yrs and 139,000 miles of driving my '05. I never brake hard at the last minute unless there's an immediate hazard and then the brakes are the best I've ever experienced.

I coast to a stop almost all the time and try to time the lights and traffic as a game ( I've always done that for 40+ yrs of driving ). Most of my driving is suburban and rural highways so there isn't much need for constant stopping as a general rule. But I've spent enough time in Boston, NYC, Phila, DC, Norfolk, Richmond and the traffic corridors of I95 to be well aware of heavy stop and go traffic. But I've also spent most of my business life in those very corridors so I also know what to expect.

 

I would have to agree with this as I have never felt the sensation either (5,000 miles) and I avoid the quick braking. I will be prepare though, that is for sure.

I have had the reverse, grabby thing once.

 

Yes, I fully admit the one time I know I felt it, I was driving by myself (which often tends to have me driving a bit more aggressively) and I was speeding into a stop sign a bit quicker than typically, and I hit a bump where there was a pavement seam/match. It was dry - no wet pavement or anything. I have driven this bump many, many other times in a less aggressive fashion and felt nothing. And what I did feel went away quickly with a bit harder press on the pedal. If you know what can occur, and how to react to it, the panic-inducing surprise will be much less of an issue, or even non-existant.

 

The poll was a little confusing to me and I wasn't sure how to answer so I picked:
2004-09 Prius - about once per week
2004-09 Prius - no big deal, not a risk

It's tough for me to say as I alternate between my Prius and my Z and now my commute is real short so the frequency is probably between once a week and once a month.

When I worked in Sunnyvale, CA, if I were to drive my Prius every weekday, I can trigger the skid light almost consistently at one spot and if I were to brake there, I'd hit the "issue" for sure.

I can't provide pictures of the roadway anymore but the spot is at san aleso and n mathilda ave, sunnyvale, ca - Google Maps.

To repro, get off of 101 and go southbound on N Mathilda Ave in the rightmost lane closest to "Mo Sys" before San Aleso Ave. You should hit it just slightly before the traffic light at that intersection.

edit: It's likely due to this broken/cruddy pavement at http://maps.google.com/maps?f=q&sou....395272,-122.028896&spn=0.00007,0.004292&z=19 (thanks to Google street vew). I'm usually in that rightmost lane in order to turn right into Mo Sys (even though I want to go left) due crap left turn traffic light timings.

 

I've only had my Prius a month now, but I drive over some pretty rough roads and a parking lot with speed bumps and haven't encountered the problem yet. I drive conservatively and usually coast with gentle braking, so maybe that's why. the one time I did brake hard I was surprised by how responsive the brakes were!

 

Here's a Google Street View of the rough pavement spot where I will get the brake "cutout" every time I roll downhill to the stop sign. Google Maps I found it startling the first time it happened but I don't feel bothered by it now. However, if I have someone in my car at the time they get quite weirded out! I also get the grabby brakes, about once a month, usually when backing out of a parking stall. Neither of these problems feel dangerous, when you know to expect it, but it would be nice to see a fix.

 

i dont thing there is a problem at al
or all cars with traction control ESP,TC and what ever name's there are for it have the same problem
i drove a new 2009 car..not a hybrid last year and i got the same problem.
its just a feeling..where the cars take's control for more safety what a human experience is loss off that control..

 

I posted this in another thread and copied here as well.. Thanks
Hello All,

I've been lurking around this site since purchasing my first PRIUS back in sept 09. A prius 3 with nav and solar roof.
After reading about this braking issue for awhile now I wanted to throw in my 2 cents.
I am the systems designer for an alterative energy company that specailizes in Solar and Direct Exchange Geothermal. I find that in this market that a large percentage of people can be quick to find fault in something they do not truely understand. Many times I hear and I qoute " My old gas furnance didn't do that ". Well, simply put, this is not your old gas furnace.
In the same sense, the PRIUS is not your old car. The PRIUS is so far away and different then a traditional car it should be expected and understood that it will behave differently. Does this mean there is a safety issue? Well, I did some testing and you be the judge.
My wife and I live off a mile of unpaved road and the state of NC sometimes seems a little less then purdent about its up keep. I experence this loss of braking sensation often on this road. With that in mind I did and experiment yesterday with my new PRIUS, my wifes 2009 Corrolla with anti lock brakes and a friends 2004 Corrolla with out anti lock brakes. I tested at varius speeds and gentle to panick stops with each car and below are the results.

2004 Corrolla no ABS.
Normal speed for my road and gentle braking produced a secure and safe braking feel.
High speed and panick braking sends the car into a skid and loss of straight line stabilty.

2009 Corrolla with ABS.
Normal speed for my road and gentle braking produced a secure and safe braking feel.
High speed and panick braking engages the ABS but the stops were well controlled, straight line stabilty well maintained and felt safe and secure in all tests with this car.

2010 PRIUS.
Normal speed for my road and gentle braking produced a secure and safe braking feel.
High speed and panick braking produced the loss of braking sensation which rattles your confidence in that safe and secure feeling, however straight line stabilty was well maintained.

My conclusion is this. The braking sensation is unnerving because it is diffirent then the traditional. Things occur that you are not use too. Is this a safety issue? Again, you be the judge because the Prius in every test stopped an average of 8 to 12 feet shorter then either Corrolla. In the 04 Corrolla with out ABS had I not let off and began pumping the brakes and steer into the skids, I would have been in the weeds.

 

I found the poll format a little confusing, and I think other respondents may have as well--I gave two answers under "second answer" and none under "first answer."

I've experienced the sensation twice, and I'm anything but an aggressive driver. Both times I was driving normally at a slow speed, and braked while going over something in the road. One the first occasion the ABS kicked in, so there must have been a momentary loss of traction caused by the object in the road. The other time I was turning a corner and there was a metal plate on the road. I think I would have been alarmed, but thanks to having read about it on Priuschat, I wasn't upset. Personally, I'm not inclined to believe that there is a safety problem here. I'll be happy when it's officially investigated, but I just don't think it impairs braking in any way.

 

This is not occurring while braking "aggressively", since it only happens while in regen braking, which by definition, means gentle braking. Hence, this is not occurring only to "aggressive" drivers. Actually, I bet aggressive braking is one way to avoid the cut out, since you would be in friction braking from the beginning of your stop.

 

brakes will not brake when the tire(s) is/are airborne or slipping. it doesn't matter what car you have - a Prius with traction control, abs, etc. or a Ford Model T.

also, abs is designed to stop braking, and actually let the tire(s) roll... and not lock up, assuming you will have better control of the car while it's rolling and not skidding.

has anyone noticed that all these "the Prius brakes are a danger" threads have popped up during the winter time, from people living in bad weather conditions?

when i lived in munich, my Jetta with abs sucked because abs doesn't work well in snow and ice... to the point where it would shut off in those conditions. my Honda Prelude also sucked in the snow and ice.

 

Bob, Your poll isn't going to get very meaningful results, imho. I'm not a pollster, but I've had some experience writing them for post-occupancy evaluations of buildings and have had a class in doing so. For instance, your own response was incorrect. You stated you had the issue happen once, yet you picked "no experience". This is an incorrect response and would indicate, based on poll results, that you've never had the issue when, in fact, you state you have.

The poll should really have a response for those of us, like myself, who only clearly recall it happening once. It's not a concern for me any longer because I'm prepared for it should it happen again. It IS a concern for me as regards others because I still feel it will result in someone getting hurt down the road (no pun intended). People do dumb things when in a sudden panic mode. If that panic mode is brought about by the Prius's odd braking issue, then I do think a jury would side in favor of the Prius owner.

My bigger problem with the whole issue of counting heads and opinions is that this issue may not be present in EVERY Prius out there. Some may never experience it. Others seem to be able to replicate it at will. So, I would think that if you want to figure out if people think it's a problem, that you immediately discount any who have not experienced it as their Prius may not be effected by it. Their opinion may not matter. It would be like taking a poll to see what you think rabbit tasted like, and allowing those who've never tasted rabbit to vote. To see a count of people who've experienced it and if THEY think it's a potential safety issue or not would be more meaningful imho.

Even so, at about 7% of users in the poll who now say it's a safety concern, I think that's significant enough to warrant Toyota to approach it as such.

I appreciate wanting to get some measurements on this matter, but get some that are more meaningfully obtained.