I parked my car in the driveway the other night to take some stuff out of the trunk at the front door (garage comes in on basement level), and it was on the relatively gently slope of the driveway (maybe a few degrees ... 6 or 7?). I'd done some relatively hard braking, so I thought it couldn't hurt to park the car in gear with no parking brake so the pads wouldn't warp the rear rotors.

Well, as I swing my leg out the door, the car slid forward an inch. Then a few seconds later it did the same thing. It felt like it could be slipping on the transmission teeth.

A.) Was it the tranny teeth?
b.) Did I do any damage, or is this normal? Perhaps parking without the brake should be reserved for near-level surfaces?

 

Which gear? I'll bet you used 4th or 5th gear. You should have used 1st or Reverse because those gears have a higher (numerically) gear ratio.

No. The inching forward you noticed was the engine turning over. Each time a piston went past Top Dead Center the car rolled forward until the next cylinder in the firing order came to its compression stroke.

You did no damage. It is normal.

Always use the hand brake. If you can't use the hand brake, use wheel chocks.

 

Thanks, Daniel. It was definitely 1st gear. Always 1st or Reverse. I'll be sure to use the brake from now on. I usually do, but my recent brake warpage started changing my mind.