Grabbing Brakes and Rocking after stop.

I've experienced both. The rocking after park seems common in a lot of cars. I just try to release the brake slowly.

The grabbing thing happened to me once and is indeed weird. Taking the car out of reverse and then putting it back in reverse solved it for me the one time it happened. Seems like a system bug, and makes me feel a little uncomfortable about the brake management...

 

Boy, that's the understatement of the year! LOL! Happened to me the very next day after I brought it home from the dealer. I was backing out of my garage and brakes were grabbing like crazy! WTH? But after that one incident, it never happened again.....

 

I used to have the rocking on every level surface, including flat, until I made a point of pushing in the parking/emergency brake *before* letting off the brake and putting the car in "P" (instead of after). Hasn't happened since.

 

My car rocks a bit after being put into park, and I often have the grabbing brakes when trying to reverse out of a parking spot. Quite annoying, makes it impossible to back out smoothly. I'd been driving standard transmissions for a long time so I though maybe it was an just automatic thing, but I guess not?

 

Definitely not a normal part of an automatic.

I have a feeling we will be seeing a TSB on the grabbing brake issue, if not a safety recall, at some point.

 

thanks, I will give it a try, I was wondering why it would matter since my problem always occurs when I start the car. Does this car have some kind of "memory"

 

Wow, the grabbing brakes thing happened to me for the first time tonight. I have about 1,200 miles now and when I pulled out of the store parking lot (in reverse), the brakes really grabbed. So much so it was hard to gracefully come to a stop. I finessed it more than usual and was able to overcome it. After getting home, I tried backing up again and there was no problem.

With that said, the only difference in driving style was that I was sitting in the parking lot with the car "on" and with the AC on for about 12 min.

Peter

 

I asked my dealer about it today when I test drove my car which arrived today. He told me that it has to do with how HARD one hit's the brake, so maybe try a little different touch and experiment a little. When you press HARD on the brake is when it happens more he told me from his experience. I drove mine normal and tried that and it seemed ok (today) but I pick it up Friday so will see what happens then with more time.

Do you apply the Parking brake as well when parked at all???

 

Until you can get Toyota to fix this problem with grabbing brakes, try placing the car in park and then start over. So far, that has worked for me. The rocking issue does not concern me.

 

I don't believe what your dealer said at all. Now I will say braking has gotten much smoother since they have broken it. However this is the first time the grabbing has happened to me (1,200 miles now) and it was really noticeable. But like anything that happens on occasions, it is gonna be hard to convince Toyota something is wrong. Again, I was able to make my maneuver without incident but it was disconcerting.

I try to use my parking brake as often as I can remember to because I don't like to think about what the rocking is doing to the drive train.

Peter

 

Yeah, its definitely not an issue of brake pedal pressure...it feels like you just slammed the brake down when you barely touch it. Happened to me once and was very weird...hasnt happened since. At the time I just put the car in park and then back in drive and it went away...

 

I've experienced the grabbing brake problem but it was resolved on another thread somewhere. If you ALWAYS keep your foot on the brake when shifting into Reverse you won't have the grabbing brake problem.

 

Don't you always have to have your foot on the brake to shift period (other than Park)?

 

When you say "parked on an incline for some time" how long do you mean? Hours, days, weeks?

I think everyone has experienced brake grab in the first week or two of owning a Prius. It's common enough that it's made it into Prius FAQ's.

My opinion -- agreeing with the FAQ's -- is that it's related to rust/particles accumulated on the brakes during shipment. I've certainly experienced similar grab on every car I've ever owned, if I let it sit for a week or two. And the fact that the brake grab seems to occur once or twice early in the life of the car and then never again -- in my experience and in my reading on the forums -- reinforces that.

Remember, with regenerative braking you're only using physical braking below 8 MPH, or if you brake hard, or if you pop it into Neutral before braking. And, I'd assume, in Reverse. Is it a coincidence that brake grab is reported in the two of these situations where you'd be able to feel it: creeping in forward or reverse?

Again, most every car I've owned over the years will do this if you do not apply the parking brake before letting off of the brake. The Park gear is not applying a brake, it's dropping a pin into a transmission gear's teeth to prevent it from turning, but there's a lot of slack/tension in the entire drivetrain that you'll experience if you don't have a brake (either the regular brake or the parking brake) on to actually lock the wheels.

 

For any of you who may not have seen it, there is a long and active thread on this topic in the main 2010 forum:

http://priuschat.com/forums/gen-iii-2010-prius-main-forum/65875-braking-in-reverse.html

 

Hi All,

This is usually caused by rust on the brake rotors. The Prius as you know does most of its braking electrically. The brakes can go for a long time without getting hot and driving water vapor out of the outer layers of the metal. The water vapor will then start the rust action.

The common way to deal with this is on a slight downhill, to put the transmission in N mode (not to be confused with the legal definition of disengaging the mechanical gears as the Prius never does this) and pressing the brake so that the car runs down the hill at the initial speed. Its probably wise to do this below 40 mph, and to pick a long shallow hill. Then shift it back into D mode on the fly. When in N mode, the inverter electronics are static, and the Prius cannot brake electrically as a consequence. Pressing the brakes down the hill forces the friction brakes to be used, and the rust to be ground off of the brake rotors.

If your Prius has not been used for a few days, or its rained since the last time you used it, then its a good idea to perform this proceedure as soon as practical once driving.

One thing that helps reduce the frequency of this issue, if you park the car outside, and do not live in mountanous terrain, is full wheel covers. It still happens, but with the wheel covers, rain does not splash through the openings and wet down the rotors.

 

The grabbing that occasionally happens when backing is not caused by rust on the brakes. It is clearly the brakes over applying from slight foot pressure. It is sudden and only the low speed prevents it from being a dramatic event. Even so it can give your neck a bit of exercise.