Auto transmission in park

[Bitsyncmaster]

Today I helped an owner get his parking brake working. Got it fixed but when I jacked up both rear wheels in "park" I could turn the wheels (e brake is off). The other wheel turned backwards of the one I was turning as expected.

But should the auto in park, lock the wheels?

[David T]

The auto works just the same way as the 5-speed. If you raise both rear wheels off the ground and put the auto in Park, turn one wheel, the other will turn the other way. What you have to watch for on either is when you apply the parking brake (aka Emergency brake) BOTH wheels lock at about the same time. You do NOT want to pull the emergency brake and have only one rear wheel lock up. If that happens NOW YOU HAVE A REAL EMERGENCY, especially if the road is slippery like with rain, snow or ice!!!!!! The only way to lock BOTH wheels is with the E brake. One way to test the E brake is to get up to about 25-30 MPH and jerk the brake on. You should see equal length patches on the ground. Don't try this in traffic!
David Teitelbaum

[Rich]

But should the auto in park, lock the wheels?

Park position in automatics locks the tranny output shaft. Then the car won't move if both drive wheels are on the ground.

In Park the differential will allow wheels to spin opposite to each other if the e-brake is off and they are jacked up. Try it on any car without a limited-slip diff or all-wheel drive, you'll get the same result.

[Bitsyncmaster]

So the 5 speed would do the same? It funny I did not notice this before but maybe I never left it in gear when I adjusted my parking brakes.

Yes both wheels grab at the same point (number of clicks on handle). That is why I jacked up the rear wheels to test it. This car took more "clicks" then my car so maybe an adjustment or new pads would make it work as low as mine. But it does thoroughly lock the wheel.

Are there any auto adjusters on our parking brakes?

[DMCMW Dave]

Are there any auto adjusters on our parking brakes?

No. Just two manual adjusters on each side. The nuts on the cable and the large screw with the cotter pin through the top.

[David T]

Actually there IS an automatic adjuster for the E brake. They just do not work, never did and never will. They live in those little metal boxes. On the subject of the E brake, you must make sure both pads pivot freely on the pin/bolt and that they are equally adjusted. They must release fully or you will quickly wear the pads out. Make sure there is a cotter pin to lock the adjuster screw. It helps a lot to lubricate the cables. Especially if the car was ever in a lot of water. You should also exercise the E brake once in a while just so you know it works. It is more important to have a good working E brake in the 5-speed but even the autos should have a good working E brake "just in case". For those of you who park their 5-speeds in gear it is dangerous and you should at the very least also have the E brake on just to remind you in case you ever try to start the motor in gear.
David Teitelbaum