Car lurches forward when shift from park to reverse

[ToyotaCarFan]

I have a 2007 Camry XLE V6 with the infamous 6-speed automatic. I'm concerned about two things I noticed related to the "park" feature of the transmission:

1. If the car is put in "park" while on an incline (front of vehicle pointing uphill) and allowed to be held by just the transmission (i.e., the emergency brake is not engaged), then when I shift from "park" into "reverse" there's a thunk sound from under the hood and the car lurches forward an inch or two before going into reverse. This happens frequently, but not all the time. Is this normal?

2. When I jacked up the front end of the car with the transmission in "park" to change a front tire, I found that the wheel turned freely! Interestingly, when I turned one wheel one direction, the other front wheel rotated in the opposite direction. Is this normal?

Thanks for any insight from people who've noticed this on their own car or who are more familiar with the mechanics of this car than I am. Side note: My car's original transmission was replaced a few months back due to the 3-4 gear shift flare problem.

[gdanaher]

Originally Posted by ToyotaCarFan

I have a 2007 Camry XLE V6 with the infamous 6-speed automatic. I'm concerned about two things I noticed related to the "park" feature of the transmission:

1. If the car is put in "park" while on an incline (front of vehicle pointing uphill) and allowed to be held by just the transmission (i.e., the emergency brake is not engaged), then when I shift from "park" into "reverse" there's a thunk sound from under the hood and the car lurches forward an inch or two before going into reverse. This happens frequently, but not all the time. Is this normal?

Pretty normal to verying extents with most cars with an automatic. The weight of the car is resting on a single set of pins/fingers. You can get the same thing out of a Ford or Chevy.

2. When I jacked up the front end of the car with the transmission in "park" to change a front tire, I found that the wheel turned freely! Interestingly, when I turned one wheel one direction, the other front wheel rotated in the opposite direction. Is this normal?

The differential moves as it should. Put one tire on the ground so it can't move and report back.

Thanks for any insight from people who've noticed this on their own car or who are more familiar with the mechanics of this car than I am. Side note: My car's original transmission was replaced a few months back due to the 3-4 gear shift flare problem.

[sigmund]

Not trying to flame here but why are you parking on an incline without using the parking brake? What do you think the parking break is there for? To take the pressure off the transmission and to keep the car from moving especially when parked on an incline. I would suggest you use the parking break when parked on an incline.

[CamrySExxx]

^many people never use their parking break. For the gen6 i hate using the parking break in the autos ...id love to have the e-brake with the handle over the pedal. HAlf of the time i park i just put it into park and let the tranny hold the car

[lammydi]

Originally Posted by CamrySExxx

^many people never use their parking break. For the gen6 i hate using the parking break in the autos ...id love to have the e-brake with the handle over the pedal. HAlf of the time i park i just put it into park and let the tranny hold the car

I am the other way around...I love the pedal e-brake and hate the handle e-brake. Each to their own!

[eledan]

Perfectly normal for automatic transmission on a hill. Since there aren't many hills in my town, I haven't practiced ways to lessen the load on the tranny when shifting...But I imagine keeping the e-brake on while shifting would help.

Personally, I like the pedal e-brake, only because it's what I am used to. Handbrakes are good for drifting though...

[sigmund]

IMO the best way to park on a hill and lessen the load on the transmission would be to do the following:

1. Apply the brakes.

2. While keeping pressure on the brake pedal apply the parking brake.

3. Shift car into Park.

4. Release foot from the brake pedal.

For starting off on a hill:

1. Start car and apply foot on the brake.

2. Shift car into Drive.

3. Release parking brake & go.


That's how I do it anyhow and I've never heard any "thunk" or had any problems with the car lurching.

[touringcamry]

^
For slow maneuvers on a hill such as parallel parking or starting from a hill, I find that it's useful to use both feet to drive an automatic. With the car in gear, either D or R, hold the brake pedal with your left foot and use your right foot to hold the throttle down slightly so that the engine is at maybe 1000-1200 RPMs. Then modulate the brake with your left foot to control movement of the car.

BTW, how do so many of have the pedal type parking brake when most Camrys have handle type next to the shifter.

[ToyotaCarFan]

Originally Posted by sigmund

Not trying to flame here but why are you parking on an incline without using the parking brake? What do you think the parking break is there for? To take the pressure off the transmission and to keep the car from moving especially when parked on an incline. I would suggest you use the parking break when parked on an incline.

Normally, I use the parking brake. However, when I want to enter a destination into my navigation system (which requires that the car be stationary during entry for "safety purposes"), I back the car out of the garage and put it in "park" on my slightly inclined driveway while entering data. This avoids filling the garage up with fumes while punching in the data. Sometimes I just gently release the foot brake during the process if it's taking awhile. Then, the "thunk" occurs upon subsequent shifting out of "park".

[ToyotaCarFan]

Quote originally posted by gdanaher: "The differential moves as it should. Put one tire on the ground so it can't move and report back."

Thanks for the info. So, the parking pawl is evidently located upstream of the differential, in the transmission itself, and effectively locks the engine's propeller shaft rather than the wheels' axles. Interesting. This would imply that if someone jacks up the rear of their car (e.g., to change a tire), the car body could rotate about a point midway between the front wheels, even when in "park". Yet another reason to chock those wheels when working under the car...

It would seem that only one wheel is effectively resisting motion when the car is in "park" -- the other one is allowed to rotate, right? So, if one wheel is on a patch of ice and the other is not, the grippy wheel will rotate and allow the car to move while the slipping wheel will spin forward on the ice, right? This doesn't seem like a good design, considering that emergency brakes have minimal holding power. (Yes, I know about pointing the wheels into the curb when parking on an incline, but the reality is that many people don't bother with that.)

[thoots]

I just can't even begin to comprehend people who refuse to use their parking brakes. They might as well put a bumper sticker on the back saying, "I don't give a sh!t about my car."

I have always used mine, 100% of the time.

And, I'm really quite happy with the parking brake pedal -- how elegant to get the darn "hand brake" out of the otherwise very useful console area! I really think it gives the car a touch of class.

[CamrySExxx]

Originally Posted by touringcamry

BTW, how do so many of have the pedal type parking brake when most Camrys have handle type next to the shifter.

IIRC... gen6 AUTO have the foot pedal while the manual have the hand break