If you put the front end on ramps and then jack up the rear, you need chocks to stop the front wheels rolling off the ramps. The transmission and e-brake only act on the rear wheels - as soon as they're off the ground, the front end can roll, and so can your jack. If you're lucky, that will just shove the jack handle where you really don't want it, as 3400 pounds of car comes back down the ramps. Possibly a lot worse.
I mention this because the link in Post #3 doesn't.
Oh, sorry, just noticed dmax mentioned this too. But it's specially important if you're on ramps at the front.
Engineers do it with a torque wrench
Last edited by Wolrab; 10-16-2012 at 04:48 PM.