dcarlinf1

OK, but why? What is it going to hurt?

Chromeshadow

I look at the "gain-risk" of using the differential. If you distort the housing by 5 or 10 thousands, you can risk shortening it's life.
You are also supporting the car in the reverse direction- normally the weight of the rear of the car is on the wheels and transfered to the springs, compared to jacking on the diff puts the entire weight of the rear of the car on the joint where the axle housings connect to the diff. Kinda like using a crowbar on the axle housing. There are other good locations to use that have no risk. What do you gain? You save a few minutes by not putting the jack in a better location.

xkape

Theres a thread over on fnsweet (forget the posters name).. he came up with something.. I didnt understand it til I had to jack my car up this weekend but, excellent idea for under the car stuff. He made, basically, a ramp out of wood to drive up. He gives the exact dimensions of the wood and a complete how-to to put it together so that your bumper does not hit at the low heights of our cars. If you are changing wheels, it wont help much but, if you are under there messing with the exhaust or driveshaft or anything else, this is pretty nice and very inexpensive.

808muscle

I built some drive up ramps too. 18' then another board..did 3 layers using 2x12 wood. And if that's not high enough I have another 18' board I can use but you gotta use the jack to get that in there. I can drive on these ramps forward or reverse onto them. I also made some wood blocks when I need to get the entire car in the air. 2x12 24' long stacked 3 high. Even when using stands I like to have something under the wheels.
I jack from the pumpkin but have a rubber ended jack.