HELP Prius "rocks" while in Park??

Nope, that's just the slack where the parking pawl sits in the "tooth" in the gear. Nothing to worry about.

Dave

 

Yes, it's normal. But you do use your parking break too, don't you?

 

You should always use the emergency parking brake!!

the Park feature on any automatic transmissions is not a solid mechanical linkage that restricts the motion of the car. While 99.99% of all circumstances will not override the Park feature you never can tell when the gear or the servo controlling it may fail.

Also, the use of the E-Brake will keep the linkage free of dirt and debris and working properly. I've know people that have not used their brake for a long time then they get into a position where they need to use it and it either does not function or it refuses to disengage.

 

What’s the use in setting the emergency brake while parking on level ground? No way am I going to go through that useless motion every time I enter and exit the car! Manual transmission, sure . . . but not in an automatic with a parking pawl and on flat ground!!! :roll: What a waste.

[This would actually make for a fun Site Survey (poll) . . . "Do you set the Emergency Brake on flat/level ground?" . . . but unfortunately the current Site Survey is rather new.]

Not to confuse people . . . but that is about as useless as pushing the Parking button [P] before pushing the power button when you are turning the car off. If you don’t believe me, be bold and only press the power button and watch the parking button light-up . . . signifying it has been actuated by the computer.

Yes, the rocking is normal . . . and no harm will come to your car sitting on flat ground because the emergency brake was not set.

 

<div class='quotetop'>QUOTE(Sufferin' Prius Envy\";p=\"80090)</div>

To stop the parking pawl being sheared off if someone backs into your parked car?

 

Never using the P-Brake can cause other problems.

 

I always use the parking break and the emergency break when I park. I still get the rocking but have never though much about it since one of my old trucks did it also.

Why use both? As an engineer why he uses a belt and suspenders. If one should fail then the other acts as a back up.

It takes me a whole 1 sec to engage the emergency brake while I hit the power button and vice versa. It is only a useless motion until something happens and you needed the emergency brake engaged. But to each his own.

 

Well, it's called a "parking brake" for a very good reason.

I have seen and - even more fun - *heard* problems with a parking pawl in an automatic transmission. In some cases the pawl hangs up and doesn't fully engage or disengage: it ratchets as little slivers of metal get shaved off and circulate through your transmission.

In many cases, parking on an incline is a *great* way to bugger up a parking pawl. My 2000 GMC Sierra had plenty of warnings about "torque lock" and how you would need a push to take the pressure off the pawl.

As Kam mentioned, even a relatively minor low-speed bump from another car can bugger up the pawl. What usually happens is the pawl really seats into the notch and you can't get out of Park.

On every vehicle I have ever owned or driven, I've used the parking brake.

 

<div class='quotetop'>QUOTE(Devil's Advocate\";p=\"80084)</div>

While I agree that using the parking brake (particularly on an incline) is a good idea, I've never heard of an automatic transmission build in the last 30 years that *doesn't* have a solid mechanical linkage restricting the motion of the car.

I'm not sure how much more solid you can get than a heat-treated 1/4" thick steel parking pawl engaging a similarly strong toothed gear.

In fact, most problems people have with not using parking brakes are due to the parking pawl doing its job *too* well.

 

yep, ratrent the "pawl" is a solid mechanical tooth that engages, but it engages "AUTOMATICALLY" which, while I love technology, and even one as proven as the automatic transmission, Automatic has a bad tendency to not be very Automatic at the worst possible times, where as when you step on the E-Brake you know it is engaged instead of "assuming" it has engaged. And yes even the E-Brake can fail so it is not completely 100% trustworthy (maybe something like 99.9999999999999987%), but not using it leaves you at 0% ineffective

 

If someone taps my bumper while playing bumper tag parallel parking, I for one would want my car to give a little rather than sacrificing the bumper while the car acts like a pliable brick wall with the parking brake applied.

I know it was a figure of speech . . . but 99.9999999999999987% ??? Not even aircraft wings are manufactured to that level of reliability PER FLIGHT HOUR!!! I’ll trust my Prius on flat ground with 100% ineffective parking brakes (not applied).

Correct me if I am wrong, but doesn’t the emergency/parking brake only apply the rear brakes?

If someone were to run into your bumper with enough force to damage a 1/4" thick steel parking pawl, it will make little difference if the parking brake was applied or not! The front wheels will be moving, and therefor the pawl will receive a jolt, but the car would probably be totaled before the pawl is damaged. I’ll take my chances with protecting the bumpers from a more probable slow bump at the risk of damaging the pawl in a more severe crash.

Hills are a different story. Curb the tires, but without loading the tires with weight on the curb unless you want tire damage. Stomp on that parking brake while your foot is still on the regular brake pedal, put car in neutral, slowly release normal brake, then turn car off. This maneuver will keep the pawl from being loaded with pressure and allow for a smooth release. When you return, start the car. Keep your foot on the brake and shift into gear. Release parking brake. The pawl should have released just fine.

 

Your analogy with the Power button would only be accurate if the computer set the parking brake as well. ALL automatic cars are supposed to have the parking brake set when leaving the car, for safety and to prevent transmission damage. It says so in the owners manual and I learned it in drivers ed, on my driving test at DMV when I was 16, etc. etc. etc. Just because something isn't needed very OFTEN doesn't mean it isn't needed. Safety and security are based on multiple redundancies. Getting close to 100% means overlapping systems that might not be used much, if ever.

The Prius probably rocks more since it's design isn't like a regular auto trans and is possibly easier to damage when parked since everything stays connected and "park" is electronic, not mechanical. I try to remeber to set the brake, I live in a city and don't like the car moving when people touch or bump it when parked on street. Usually, I forget but am tryign to get a system... it was easier with a manual trans and the brake located where the armrest is, but I am very happy to have the nice console there instead of the brake.

Your choice not to use it is your own, and probably you will never have a problem. But calling it useless and an eye roll is inaccurate & misleading.

 

The Prius's parking mode is not electronic, it's mechanical. There's a nice big parking pawl just like on any other automatic transmission.

 

I engage the the parking brake before putting the car in park. i feel this may help with wear and tear.

The parking break is the last thing i take off too. This way i have no worry about rolling at any time.

 

I should have been more specific. In this instance, I was trying to say:

Electronic meaning "a device controlled electrically" as in electronic transmission (electric control but gears are mechanical).

Mechanical meaning "fully operable with no electricity" like brakes & steering (without the assist, ABS, or other electronic components).

The mechanical effects of parking remain even after the electronic contrller is disabled. Getting the car into/out of park wouldd be very difficult w/o the computer, setting/unsetting the brake is independent of the rest of the car. It is very common for electronic systems to have backup mechanical controls as failsafes. I don't expect to see complete by-wire controls for steering or brakes anytime soon. Even though electonic systems are very reliable, they have all the potential error of mechanical, plus a few more (sometimes unpredictable).

On another note, leaving my manual trans car in 1st gear yielded a similar roll to the Prius. Almost everyone with a stick uses the brake, even though in gear it was unlikely to move and someone would have to hit it hard to cause damage. I got into the habit b/c I found it unsettling for it to roll even a little. I never expected my car to be damaged when I forgot, nor do I expect the Prius to be either, but I won't be the test subject either. The PSD on the Prius parked is more like a manual trans in gear with an the addition of parking pawl since engine, motor, and wheels stay connected.

 

The service manger at Saturn Dealership (my last car) suggested either ALWAYS using the brake, or NEVER using it. He said not ever using it, then setting it one day years later is asking for a world of repair bill hurt.

 

Well, actually, no. When the car is off, the motors are freewheeling in the Prius (and thus the engine has no torque on it either), just like a regular automatic transmission (though in a traditional auto tranny it's because the torque converter has ~zero coupling at zero RPM).

The only difference would be manufacturing tolerances and the fact that the parking pawl on the Prius is before the final drive assembly whereas on most traditional trannies that I've seen it's after. This would tend to make it stronger (for a given amount of steel... so probably lighter in practice) but sloppier.

This, of course, is assuming there is such a difference... I have had a lot of auto tranny cars and don't see the Prius as all that much sloppier.