I am going to cross post this for you Prius drivers who have more experience with these cars...

Since I am bringing my TCH in for service tomorrow to look into the gurgling sound behind the dash (seems like air in the cooling system after radiator replacement following deer collision), I wanted to ask them about the brakes. I wanted to hear from a couple of you and see if this is common.

I have noticed that when I decelerate to a stop (lets just say from about 50mph), I can slow down smoothly except for the final couple of feet. It feels like the disc brakes are grabbing suddenly, and it makes it feel like a semi-panic stop for those last couple of feet. It borders on embarassing when I have someone in the car riding with me. I can also feel a transition if I am creeping forward with the foot on the brake (kind of like a quiet "thump" I can feel in the pedal). I suspect this is the transition from regenerative to "pad" braking, but it seems VERY abrupt.

In addition, I have noticed that sometimes it seems difficult to keep the car from creeping forward at a stop light without applying what seems to be excessive pressure to the brake pedal. My foot can actually get tired. At the same time, when I am stationary, with my foot on the brake, I can have the energy monitor showing that the wheels are feeding regenerated power to the battery, and if I step on the brake harder (and hear/feel that subtle "thump" transition), the flow of power will stop. Obviously this doesn't make sense since the wheels are not turning.

DOES ANYONE ELSE SEE THESE SORTS OF THINGS?

Thanks!

 

Jeff,

Your system needs an adjustment as your friction brakes are sticking. The grab occurs at about 7 MPH as below that speed the regenerative braking becomes ineffective. You feel the transition to REAL friction brakes.

The transistion is normally detectable, but not harsh.

JeffD

 

Thanks, Jeffrey.

This is something that can be adjusted (in software) by the dealer, then?

 

I would suspect something else as the software is very unlikly to be the fault. I would expect a malfunctioning sensor to be the fault. Since it sounds to be reproducable and no doubt, you are still under warranty, just keep at them until the problem is solved . . . patience may be required. But after the second trip, ask for escallation.

Bob Wilson

 

I have had this happen to me as well in the recent months in my prius. i have also had a fuel injector problem and so far my brakes have not been 'grabby' , i am sure this is probably not related as I am clueless whn it comes to cars

 

I have put over 41,000 miles on my 2005 Prius, and have occassionaly noticed that my brakes get "grabby" from time to time, although it can almost always be attributed to wet conditions.
Remember that on a Prius, the physical brakes don't kick in until about 7 MPH under normal stopping conditions, so they don't have the same amount of heat/friction/time to wear the rust off of the rotors that occurs on all cars when it rains, making them stick more than usual. I have been following this situation since I first got my car, and can anticipate when it will happen. The Prius simply doesn't wear the rotors like a normal car because of the regenerative braking, so the rust doesn't come off as quickly. I have found that if you do a hard stop (20-0 MPH, obviously when no one is following/around), you can wear off the rust all at once and that has always eliminated the problem for me.

 

Good points on the rust. I might have to try the 20mph panic stop sometime.

Thanks

 

Jeff,

You can also just put your TCH in neutral (no regeneration) while moving and apply the brakes. No panic stop required to use the friction brakes.

JeffD

 

Thanks,

I hadn't thought of that either! On a side note, it is actually surprising how quickly that the battery charge decreases when you are in neutral (in a carwash on a hot day, for example).

 

Jeff,

Just shut off the AC and lights in the car wash to save energy (and later - gas).

JeffD