Poll: Are Prius brakes a problem?

Bob,

With all due respect, it might be impossible for us as owners/drivers to safely document the items you're asking for. I, for one, don't want to have to pull my car over and take pictures/measurements of a pothole I may encounter that might cause the effect. I don't want to encourage people do put themselves in harm's way by finding such metrics.

Also, based on the observations of many, I don't see how using casual methods readily available to the general public one can find much meaningful correlation between the events and the sensation. It's SO fleeting that unless you're somehow hooking someone up to an EEG machine that's synchronized with high speed frame cameras, I don't see how you can determine exactly where the sensation begins in relationship to hitting the uneven pavement surface. I say just leave that up to the experts and let us, as ordinary (or even the few extraordinary- you know who you are) drivers note our personal, subjective observations and let the experts take it from there.

It's still important observational material that should be taken into consideration by those experts.

 

I bumped this because it gave me a reason to reflect.
Here are my thoughts:
1. I do find the prius a completely different drive from the last car I owned. Perhaps I have gotten used to the way the car accelerates and the way it breaks so I simply don't notice the sensation?
2. If it is true that the car stops as quickly as any car on the road, then it must be the sensation that is unnerving. However uncomfortable and unnerving a sensation might be, it is only a perception of risk where risk does not exist.
3. If the car is as good or better at braking and it is the sensation created is the problem, then is it really something that should be fixed?
This in no way negates the fact that you feel a sensation of no brakes, but perhaps a few tests of stopping power would make you feel more comfortable with the brakes in the prius?

 

Bob, the lack of feedback on this thread falls under the "talk is cheap" category.

Tom

 

Here is a reproducible spot. Going east brake to slow as you approach a round-a-bout. The car lurches strongly as it goes over an uneven patch with a dip in it.

Enter this into Google Maps: W.19th and Laurel, Vancouver, B.C.

 

The patch that causes the problem here is only on the south west corner of the round-a-bout. It's slightly downhill, so you tend to brake going into it. That's when the car lurches strongly in response. I now use it as entertainment, like on an amusement park ride.

 

The spot is the left image at where the white line begins. Braking to slow at that spot reproduces the symptom noticeably. That is the only spot that does it. No where else on this corner causes the problem, so the second image doesn't apply.

 

bergen county NJ
fall
continuous line of leaves at the curb coming out about 2-3 feet
in NJ the home owner pile the leaves in the street for pickup. they can sit in the street for several weeks and in this downhill section they formed one continuous line.

rainy day

25 mph with traffic around me

the right side of the car was one the leaves when i started to break. at first it was like nothing was happening then a little abs action as i pressed even harder. as i came to the intersection i was headed straight toward the side of a car. my car entered the "intersection box" i turned my front wheel to the right to make the turn and they finally grabbed, because they weren't on the leaves anymore, a then i proceeded around they corner.


at first i was in regen mode but, i still question as to if i was out of regen into abs brakes before the "grab and turn"


it's hard to tell but it is downhill.

map from microsoft bing

 

I have this entered on another thread but had the regen brakes release over the two manhole covers for a fraction of a second and then the frictional brakes worked as I pushed. No perceptable increase in braking distance; no problem. See NHTSA thread for details.

 

This is the site of my most noticeable of two occurrences. It happened last fall and the road was dry at that time, it had rained a few hours before this picture was taken. The pot holes may not have been in exactly the same place at that time but they would have been close.

 

This is the second, less severe incident. I was in the right turn lane and the problem occurred somewhere around the manhole cover. The street is the same today except it was dry when problem occurred. Both this and the previous incident happened last fall and I have had no other problems in several thousand miles. I have tried to recreate the problem but have not been able to do so.

 

Here's the bump that put you on an amusement park joy ride, at W.19th and Laurel, Vancouver, B.C.

[ame="http://www.flickr.com/photos/claude_photos/4285458117/sizes/l/"]Flickr Photo Download: bump[/ame]

 

Any condition that will trigger the very-sensitive skid "sensor" (even very briefly) appears to turn the regen braking off for about a second.

 

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.