Brakes grabbing

<div class='quotetop'>QUOTE(lowspeed @ Jul 3 2006, 05:58 AM) [snapback]280465[/snapback]</div>

thanks lowspeed. i knew it was the regen to friction transition, and i guessed it was "normal" prius engineering / behaviour.

and maybe this helps explain? i called my dealer this morning, and they say the regen to friction braking "transition" (lag) time gets a bit longer as the brakes wear. they claim there's little or no lag in a new car, and then a gradual increase in the lag time as the pads and rotors wear. if you have the car from new, you might not notice the gradual change so much. they claimed the lag time would decrease with fresh pads, and the cycle starts over.

and thanks all for this reaaalllly long but useful thread. i read every word of your sage advice. drive on.

 

In general the transition is much smoother if you keep your brakes
*clean*, and do the friction-only-stop chicken dance every so often
especially on damp days. Otherwise, that is indeed the way it is.
.
_H*

 

<div class='quotetop'>QUOTE(cagemo @ Jul 3 2006, 05:09 PM) [snapback]280641[/snapback]</div>

brake pad and rotor wear? haha!

DH scrubbed an area of our rotor with some kind of rough thing way back when and oh, over 5k later that mark is still 100% visible.

there is virtually no pad and rotor wear in this car.

after 16k ours still has the original rotor machining marks.

well anyway i've been driving conventional cars lately (one part of visiting the hometown that i HATE) and will see if i notice a lag time when i switch back to the prius.

 

When my car was new I noticed a lag at 8 mph but now it seems to be gone. But I do notice it at faster speeds braking, when the dynamic braking stops early.

Sometimes this is because a wheel slips, but other times I have no idea why it stops the dynamic braking.

Getting used to it though.

 

<div class='quotetop'>QUOTE(tomdeimos @ Jul 4 2006, 07:55 AM) [snapback]280942[/snapback]</div>

I'm starting to get that moment before stopping jitter again... Wth. Why didn't the 2004 model have this problem ?

 

<div class='quotetop'>QUOTE(lowspeed @ Sep 5 2006, 11:25 AM) [snapback]314544[/snapback]</div>

Don't know if this is what you're talking about, but I find that I can't 'smooth' out the last 4 or 5 mph by slowly lifting my foot off the pedal like I can with other vehicles. It's feels more electronic than say a smooth cable release of the brake. Hope that makes sense.. The brakes release a small amount, but suddenly, rather than smoothly.

 

<div class='quotetop'>QUOTE(Jonathan @ Sep 5 2006, 09:20 PM) [snapback]314888[/snapback]</div>

This is just before the car comes to a stop, so i'm probablly at 1-2 mph the brakes release and then grab again. (it's all very quick release and grab.)

 

Has anybody been able to demonstrate this problem to a Toyota techie ?

I went 3 times spent 15 minutes driving with a tech and each time i couldn't duplicate this issue.


I'm surprised this thread is dead because this issue really bugs me.

 

I have only tried once, but have not been able to make this "grabbing when trying to come to a smooth stop" appear with a tech in the car. I did have an offer from a local dealer that if I was able to demonstrate it, they'd be more than happy to "hook up the analyzer to the car" and measure what's happening when it occurs.

Good luck on that, I suppose, but I hope I can get it to show up at the right time some day.

I know of 3 other local Prius owners who are similarly attentive to their car, and none have noticed this effect. It happened once when one of them was in my Prius, and they agreed their Prius had never done anything similar and are confident they would have noticed it.

I am wondering if brake pad composition has something to do with this? Granted, all Prius have the same brake pads, but there's sure to be some variation from car to car, or varying properties of the rotor for that matter.

I've considered non-OEM brake brade replacement as an experiment, but haven't tried that yet.

For anyone who has noticed this, do any of the following ring true for you?

(A) tends to happen more on colder days (55degF or lower in my case)
(B) tends to happen more on wet mornings, i.e. foggy (true for me, but also tends to be cooler on those mornings)
('C) do you regularly drive in a dusty environment? (I live on a gravel road, maybe 300 yards worth)
(D) has it ever behaved like this while stopping in Neutral? (once for me)
(E) tends to happen more in the rain (not for me)
(F) tends to not happen for awhile after doing some Neutral braking (typically true for me)
(G) does the car ever shimmy side to side a bit when it happens (a few times for me, kind of subtle)

I keep trying to find a correlation between some environmental thing (temperature, foggy, dusty) and the grabby problem, but it hasn't been obvious yet. I have noticed on a couple of occassions that city driving on a clear warm day (in California) tends to be trouble free, which kind of lends credence to the thought that it's just muck on the rotors or pads that gets cleaned off with a fair amount of friction braking -- which leads me back to wanting to try some non-OEM brake pads to see if they deal with the possible muck better.

I've chased most of the plastic rattles out of my Prius, this is the last nagging nag about the car, except for my dissatisfaction with a not-so-adjustable driver seat. I wish I could just live with it, but apparently I'm not wired that way.

Mike

 

This thing seems to be so random... it usually happens when you least expect it.


so far i have yet to find a pattern but for the fact that it never seems to happen when a tech is in the car



I'm going to have to sell the car on ebay ... (get the joke ? )

<div class='quotetop'>QUOTE(SebMike @ Oct 9 2006, 06:57 PM) [snapback]330284[/snapback]</div>

to answer the questions see my comments after

So we have F and G in common.


I would also add that i think it happens more when the ICE is off.

 

<div class='quotetop'>QUOTE(lowspeed @ Oct 9 2006, 04:14 PM) [snapback]330287[/snapback]</div>

Did you intend your reply to have comments after each thing I described? I wasn't sure what "to answer the questions see my comments after" meant...

Mike

 

<div class='quotetop'>QUOTE(SebMike @ Oct 10 2006, 03:05 PM) [snapback]330768[/snapback]</div>

I put them in the parenthesis like you did after the questions..

 

This thread died because item (F) is, and always has been, the right
answer, as detailed months ago. Your brakes are self-cleaning! As
seen on TV! Take advantage of it.
.
_H*

 

10,000+ miles on the car. Still happens sporadically, no pattern connected to temperature or drive time.

Still unable to duplicate at the dealership (been there twice about this when I went in for 5K and 10K service).

 

I have had the same problem. At very low speeds 2-3 MPH it tends to grab-release-grab-release before coming to a gradual stop. And thats only when i tend to release the brake pedal lightly. The vehicle stops with 2 small jerks. Its embarrasing when i have to answer co passenger queries regarding that. I have started experiencing this behaviour since last 1000-1500 miles currently 10,000 miles. Never experienced that before. Talked to dealer only to get 'its normal' answer. Havent got time to discuss it with tech. I am planning to take it on one saturday and spend some time there. I have been able to reproduce the problem 'or charachteristic as some may say' whenever i need. hope i can reproduce it when tech is next to me.

 

<div class='quotetop'>QUOTE(AAWADKE @ Nov 1 2006, 11:07 AM) [snapback]341970[/snapback]</div>

I think your problem is a loose nut behind the wheel.

What's up with you guys anyway? There is no "problem." This is the way the brakes work in this car. The transition between regen braking and friction braking is acting as designed. No amount of trips to the dealer or nit-picky complaints will change that. So many things about the Prius are different, why is this issue one you can't accept?

If you're "embarrassed" of how your car brakes, then don't brake and see how you feel.

 

<div class='quotetop'>QUOTE(McShemp @ Nov 1 2006, 01:26 PM) [snapback]341989[/snapback]</div>

I know ur problem....u simply do not want to understand...or probably a loose screw in your head.....I am pretty much aware of the regenerative braking and mechanical breaking........and happen to have read many posts on how it works and stuff.....but why is so difficult for you to understand that there could be something else....and for your information i have driven my cousins prius and have not found similar occurences. rather even my car behaved differently before.......its certainly not the regenerative to mechanical transition thats for sure..........

 

<div class='quotetop'>QUOTE(McShemp @ Nov 1 2006, 01:26 PM) [snapback]341989[/snapback]</div>

What's your problem ?

Actually that's exactly the problem... people like you. I get the same freakin attitude at Toyota service.

 

FYI, this is from another thread on the same subject, but thought I'd post it here for anyone who finds this thread instead of the one where lowspeed is trying to take VINs from anyone who cares to pursue the occurrence:

Understood, for many, it's attributable to it just being the way it is, but several of us unrelenting types, we can't let it go... I could probably let it go if it weren't for the fact that coworkers with the same car have never noticed it, and in fact have noticed it in my car and wonder "what's up with that?". Anyhoo...



QUOTE(lowspeed @ Nov 2 2006, 09:22 AM) *

I really think this happens in a very limited amount of cars. maybe less than 1%, and i think only 06's

I want to start a VIN# collection. Maybe we can find a pattern.

Please send at least your VIN # and name to [email protected], you may also include a phone number, but that's optional.

If we get enough people participating i will be able to at least contact Toyota's president office to get this escalated.
Thanks!
P.S only cars that have the "before stop stutter"... AND PLEASE read the entire thread to make sure your problem matches these symptoms.

 

Thanks SebMike,

Here's the other thread:
http://priuschat.com/index.php?showtopic=16922


This thread though has 2 topics, one the stutter and the other is the different feel when the car transitions between regenerative/mechanical to purley mechanical.

So if you are bothered by a stutter problem right before the car comes into a stop, email me:
[email protected]

So far i have 5 VINs. This will be the last post on this thread as the other thread serves it better.