Brakes grabbing

My new 06 has the same release-grab behavior described by Paul. It is not a warped rotor pulse. It is an abrupt reduction in breaking followed by an immediate re-application at a slightly reduced pressure. It occurs when gently releasing the brake pedal at low speed (under 5 mph for me) and very low pedal presure. I believe the brake by wire release mechanism/valving simply lacks human finess. Still it's very annoying as it counteracts my attempts at making smooth stops. I have not tried bedding my brakes as suggested by Hobbit.

 

Yup, same here for sure. To me it feels like the "creep" battling it out with the brakes. Almost as if creep is trying to come on too soon, and needs a bit more delay for when I'm REALLY off the stop pedal.

 

Just standing up to be counted here.

My 2006 with 1500 miles has it too. It definitely is not a warped rotor, and it definitely wasn't on the 2004 I test drove, although it seems that a lot of 2005's have it. My first thought was that the pads just need breaking-in, but after having bedded them a fair bit, I'm convinced that's not it. Modulating improves it, but it is really difficult to get a very smooth stop.

I guess that's good news from stevehj that Toyota is aware of it, but how do we collectively amass enough wieght so that a TSB gets made? I.e., does just complaining to the dealer about it wind up with Toyota hearing about it and acting on it?

Dave

 

Just standing up to be counted here.

My 2006 with 1500 miles has it too. It definitely is not a warped rotor, and it definitely wasn't on the 2004 I test drove, although it seems that a lot of 2005's have it. My first thought was that the pads just need breaking-in, but after having bedded them a fair bit, I'm convinced that's not it. Modulating improves it, but it is really difficult to get a very smooth stop.

I guess that's good news from stevehj that Toyota is aware of it, but how do we collectively amass enough wieght so that a TSB gets made? I.e., does just complaining to the dealer about it wind up with Toyota hearing about it and acting on it?

Dave

 

Actually, my 05 has this when new. I don't know when, but this brake release feel below 7mph is gone. Rough estimate is around 5k miles. My car now has 20k miles.

 

I have an 05 Prius w/ 5500 miles on it and I too have been experiencing the same sudden grabbing sensation, making for a sudden and noticable uneven decline in speed. It happens when the vehcile is at low MPH and approaching a stop. It is an annoyance. I intend to ask about it at my next service..BUT, I am not overly optimistic that I wil receive an informed and honest response. Time will tell.

 

Well I tried the "smooth-stop-in-Neutral trick" today, and my initial observation is that it DID make a difference.

My Prius is loaded with salt right now, and no doubt so are the rotors...I was experiencing the sudden grabbing sensation, BUT I tried the "smooth-stop-in-Neutral trick" and it seems to have provided relief. We'll see how long the relief lasts.

 

I have the same exact problem. I'd really like to do something to fix it.

 

I think we all need to email Toyota with this issue. If you accept the Toyota service person's answer that it is normal and don't pursue it any further Toyota will do nothing. I plan on sending an email. :lol:

 

As per my earlier post, I do intend to discuss this with the service manager and then the sales manager at the two dealers in my area. Usually you can get further with the sales manager in my experience. But, I do think this should be a service bulletin on the vehicle and Toyota should have a fix for it. However, without pressure it won't occur.

This affinity group is the perfect group to take up such an issue. We all love the vehicle and swear by it, but also believe that with all the incredible technology the car does possess, the brakes should perform perfectly.

Any ideas on how to proceed? :mellow:

 

we have this in our 06 as well. i can't stand it. i think you can work around it sometimes when you get used to it, but it happens when you least expect it.

it would be awesome to make it a TSB and have someone just look into what could be causing it or just have a real answer from toyota themselves on why this happens.

 

I just wanted to add my input...

I believe this thread has 2 distinct "problems"

My problem is when i try to come to a stop ... just before the car stops sometimes it stutters... applying the put in N and grinding the brakes did help for a while, but now its back.

I didn't have this problem on my old 04 prius. Whats up with that ? when i went to the dealer Murphy's law on my side i couldn't reproduce the effect

I just thought that maybe 04 had discs that were more resistive to rust.


P.S

Now i have an 06 prius (HI package)

 

I picked up '06 just last Thursday, March 8th., and I am noticing this problem also. Wondering if this is the way Prius behaves, or is there any resolution for this problem from Toyota? With less than a week old, it is kind of bad that the brakes behave this way. By the way, it's been raining a lot and wondering if that contributes to this problem. By the way, I love my Prius B)

 

I'm considering putting a complaint with the NHTSA, I don't think its dangerous per say but it is distracting.

I wish my dealer was a little more concerned. or even pass the info to the Toyota reps so they be aware of this problem.

 

This response is assuming that the "issue" is when coming to a "normal" stop and the mechanical brakes are used. I say normal as in "I'm slowing down at a reasonable rate and now I have to stop."

Anyway, I saw this mentioned in this thread (I think). Reducing pressure on the brake pedal causes the pulsing/grabbing described. If you keep steady pressure on the pedal the grabbing won't happen.

The controls in the 2006 may have changed from previous years. I know my Prii both engage the electric motors at low brake pedal pressure when at a stop and at low speeds. I can lightly rest my foot on the brake and still see the energy flow to the motor on the MFD. Pressing a little harder stops this.

I think the issue people are experiencing is the car alternating between braking and driving when they are slowing to a stop (< 5mph). Under the right circumstances - low speeds and light braking - the mechanical brakes and electric motor can working against one another. Evidently, the controls of the car allow simultaneous inputs from the brake and accelerator pedals up to a point. There could be many reasons for this.

<<<<<<<<< Personal Rant Alert >>>>>>>>>>>>
Wanting a TSB or reporting it to the dealers and Toyota is going overboard. There's nothing wrong with the car! It's doing what it was programmed to do. It's up to the driver to learn what inputs are necessary to get the desired result. Some people don't seem to get that or think it applies to them.

This car doesn't work like your previous car(s) - even for earlier Prius and hybrid owners. Changes in driving styles may be required. Get over it and learn! Oh, enjoy your Prius driving experience.

 

The amount of braking force required to have no grabbing is too much in my opinion. Yes, one could brake in that manner to always avoid the grabbing. My other car is a 1998 Nissan Altima with 112,000 miles and the brakes do not grab at all at low speeds. What concerns me is that it appears to be grabbing mostly from the driver front side.

I can also modulate the brakes (like you say above) and by doing so, the grabbing is much less frequent and when it does occur it is only 1 or 2 grabs versus 3 or 4.

Anyway, why should I have to modulate the brakes for such an advanced car? My 1998 Nissan Altima has ABS and I don't have to modulate anything.

I understand that the Prius has normal brakes and the metal will rust due to low usage. My main question is why is it concerntrated on the driver side?

If I bought any other car and had this brake action I would complain.

 

lowspeed, where are you out of? [pm me if you don't want to say
publicly] if you're anywhere nearby, I would be happy to take a
closer look at this issue and try to determine what's really
going on. You've gotten me curious, if for no other reason than
how this thread refuses to die.
.
_H*

 

Your Nissan isn't a complicated hybrid with multiple means of propulsion. Balancing that with a robust control strategy puts the Prius in a different league from practically every other production vehicle in existence.

There's no rust problem with the brakes ... unless you drive through hub-deep water daily.

I didn't say modulate the brakes. In fact, I said the opposite. Keep steady pressure on the brakes until coming to a complete stop. Don't let off at the end until you're stopped. I don't believe ABS has anything to do with it. Nor do I think its brake pad break-in ... nor rust build up ... nor funky brake fluid ... nor warped rotors ... nor anything else. I think it's working exactly as designed by Toyota.

The car "sees" light pressure on the brake pedal below a certain speed and decides to engage the electric drive - even with your foot off the gas. then it "sees" the brake pedal again and disengages the electric drive. We've confirmed that this grabbing doesn't happen above a certain speed. Likewise, we've confirmed the grabbing doesn't happen with more brake pedal pressure when below a certain speed.

You probably feel it concentrated on the driver side because that's the side you're on.

Adapt to the car and change your driving style ... or don't. Maybe the 2006 Prius isn't for you. Have you considered a 2005 or earlier model? Or some other hybrid?

 

I don't think he should consider another car.

Toyota shoud and can fix it.

 

Erm, lemme rephrase that, since more people appear to be noticing
this stuff. I've learned quite a bit about the brake system in
this car, and how it should or shouldn't behave. For readers around
the boston area, I'd be happy to meet up, compare notes, do test
drives, etc. to determine if it's just the usual, or of there's
something really wrong.
.
_H*