Is it always safe to use the rear differential as a jack point.
 

I am going to lift my slk. Is jacking the Slk using the rear differential as a jack point safe for the car and me?

In general is using the rear differential safe?

thanks

blau

No
 

NO.
I can not state it more directly than that.

whunter is almost always more articulate than myself, but in this case I can answer the question better than him. My answer is:

NO

Not only can it be precarious making it dangerous for the person lifting the car, but you can easily destroy the rubber mounts that hold the differential to the subframe on most models.

Good luck,

Adding to the two previous responses,,, we just saw a Honda CRV that had been jacked up by the center section of the differential and the aluminum was so thin on the bottom of the case that one raised portion of the floor jack put a hole in the case. :eek:

thanks guys. I got the message NO
 

Thanks guys,

I got the message NO.

That's curious - the Haynes 124 manual says "To raise the rear of the vehicle, position a block of wood on the jack head and position the jack underneath the final drive unit. Lift the vehicle to the required height and support it on axle stands positioned underneath the rear rubber support blocks, which are located directly underneath the vehicle jack location holes in the sill." The Haynes manual is normally so good.

For those who say "no" - what do you suggest is the proper way to raise the rear of the car?

I no expert, but I jack up the rear of my 124 with a floor jack on either side at the rear jack pads. Then of course jack stands for safety.

Steve

So if you use the rocker panel lift pads to raise the rear (I also assume you use two jacks and need a helper to jack both sides simultaneously), where do you place the jackstands?

Though many warn against it, I've jacked the rear of my 201 up by the diff. carrier countless times and have never caused any damage.

I always use about a 4" long section of 2x4 between the jack puck and carrier, then gently drop the rear onto jackstands placed under the rear rocker panel lift pads.

At the front - same method under the front cross member, then drop it gently onto jackstands under the forward rocker panel lift pads or the outboard portion of the front control arms.

Duke

Haynes too recommends that method for the front.

I've raised all of the W126's via the differential countless times. The load path is through the diff into the subframe and through the differential mount into the body. The only possible weak link in this chain is the differential mount and the rubber in the mount looks very capable of handling the load for a short period of time.

I don't see the possibility of any damage to any components unless the vehicle remains on the jack for an extended period of time (several weeks or more).

Every time I do work on the rear brakes (which seems to be every month on the SDL:o ) it is raised by the differential without any apparent problems.

I can't speak for the capability of an SLK to perform in a similar manner.

A Service Advisor and a seasoned tech at our local MB dealer advised me that jacking under the differential of 124 cars was fine. For what it's worth I've done it occasionally with no problems.

I did my 83 300d and now my 86 300e under the diff the 300d I did it this way for 14 years never a problem

I've done the same thing without the use of the wood in the back. It appears that the jack puck fits the carrier very well and the steel base of the carrier should have no problem with the load.

I need to start using the wood in the front, however. The concentrated point contacts are damaging the rust preventative coating on the cross members. How's the stability of the 2x4 along the axis of the vehicle? Is the 4" (actually 3.5") contact width sufficient along the jack puck?

as long
 

as the ground is level a two by four is fine. i have also used small squares of tick plywood.

when jacking under the s classes be careful of the fins on the bottom of the diff. (this is a general warning, brian, i know you know about them)

tom w

It depends on the size of your jack puck, but a 4x4 plan form will distribute the load and using soft wood will allow the wood to deform and fit the contour of the jack puck and lifting surface. Just use good judgment.

Duke