Is jack lifting under differential safe?
 

Is it safe to lift the weight of the rear of the vehicle by jacking under the differential using a block of wood between floor jack & differential?

This is on a '98 SL500.

My goal is to raise the entire rear end an then put jack stands under the lifting pads at the sides.

HI Not to be a smart A _ _ but if you have to ask this question I don't think you should be under a car.

Be sure to block the front wheels so it does not move. The emergency brake does not work on the front wheels .
Have another person quickly slide the jack stands in place. BE SAFE. Jack M.

By the way I see that you are in Santa Barbara, I am in the San Fernando Valley. Is the Camarillo Chaper Active? I see no listings of activities?

Thanks for the answer
 

I assure you that I have put in plenty of hours under a good number of vehicles.

It's better to be safe than sorry. On the earlier MBZ vehicles, the diff hsg is a cast iron structure. When I saw that this one was an aluminum casting, I wasn't sure if it was intended to support the more than 2000 lbs require to lift that thing up in the back. The manual does not help in this either as it cites liftling the vehicle on a lift using the support pads.

When the vehicle in on the wheels, the sprung weight is not supported by the differential, but by the force of the springs on the subframe.

On this basis, I did not think my question was silly or stupid.

Sometimes some people amaze me-

This is exactly the way I lift my 129.

I think you will be OK just have some helpers as to limit the support time needed to get the jack stands under there, use a good wide block to spread out forces,
just be safe

There is no such thing as a stupid question. Only a tragic outcome because you did not ask it.

PS. I have lifted mine this way.

stopped someone from using cement blocks as jacks once - not good - so yes no question is a bad question

I never liked the idea of lifting them by the diff. But I've been lifting them there for 35 years. Also the 1998 129 has an Iron diff. It's not the case I worry about but the shear on the rubber support bushings. This is especially true on the 107 model where the aft mount is in full shear. The 129's at least has two bushings captive in a blow proof fashion. Neither has ever given me a problem.

I agree about the stress on the Diff Mounts
 

Although it is very convenient to lift the whole rear in one play by lifting at the differential. On most of the older sedans, you can find jacking points to lift one side at a time.

With the 3-link design of the R129 rear axle, it's hard to find any such places on the car. The car is also pretty heavy. They look and drive 'sporty', but they are built like a tank in many ways.