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

sorry duke
 

but what is a 4x4 plan form?

tom w

I have a adapter with a rubber pad on my 4 ton floor jack an use the diff as a lift point al the time...but I sit it down un jackstands under the control arms ASAP so dwell time is minimal.....not broken anything yet.....but who knows....maybe Whunter is right. He's been doing this (working on Benzs) far longer than I have. And I do trust him when he says something.

I have found that the bottom of the diff sits nicely in the jack puck and the puck doesn't seem to contact the fins in a way that would damage them..............but...........I really should check more carefully.

Plan form is the "view from the top" - like the floor plan of a house, so if you cut off a 4" (actually 3.5" as you said) piece from a length of 2x4 lumber the plan form is "4x4", actually 3.5 x3.5.

Duke

I will not take my car there...
 

Coming from a dealer? I will not let those guys touch my car with a ten foot pole.

The rear diff housing is mounted on rubber mounts with bolts. I guess shearing it off is of no concern??

For safety sake, You must only raise the car on its chassis frame.

You can always replace the diff but not your life.

Maybe there should be a thread/DIY article with pictures on the proper and safe way to raise an MB. That because I am a safety nut.

I raise the rear of my W126's by sticking the jack under the rear shocks. Use some wood so you don't dent the sub frame. Then a jack stand is placed under the rubber jack pad.


You see those 4 rubber jack pads that are under every MB? Those are where you support and lift the car from, the dealers lift grabs those four points.

On the front of most MB's their is usually a frame rail in from the jack pad a bit. If you want to put a jack stand under the pad that rail is a good spot to lift from. However I have only lifted W126 and W140's this way. So if you don't have one of those figure it out.

AS per MB for the 126.

Thought there was a TSB followup to that one?
 

Thought there was a TSB followup to that one?

Went thru the TSB titles here and didn't see anything contrary to what was published by MB.
http://www.alldata.com/TSB/35/84352004.html

There is a 1982 TSB for electric hoist adapter; but that's about as close as I saw. I used 1984 300SD as reference.

SORRY GUYS I DONT KNOW WHAT YOU DO FOR WORK,but it is safe to lift a car buy differential,unless it is a car that has a diff coo;er on it.Than you shouldnt,.couse it wil damage it if youare not carefull.

Yes i know i am talking against our Modurator but sorry to say but it is just fine to lift it on the diff,,Hey we get icbc car in all the time with no wheels ,so where are u going to put the jack.All diffs are conected to the subframe ,which is bushinged to the body.And yes the diff has 3 bolts ,but they are big enough to take the weight......Ok if you have aluminum diffs,they willl still take the weight,unless i sayed do not do it with the diff cooles like on the AMG's

Well, the pdf file makes it perfectly clear that MB recommends lifting from the differential. But common sense tells me not to. The differential is not designed to carry the weight of the car -- it's disigned to withstand torsional twisting.

Even if Wilhelm Maybach speaks to me from the grave -- telling me it's OK -- I'm still not going to jack my 201 from the differential.

But, hey... that's just me.

Jeff Pierce

You are expressing a differing opinion.
 

What is an ICBC car?

ICBC - Insurance Corporation of British Columbia
www.icbc.com

Where does bait car funding come from?
http://baitcar.com/where_does_bait_car_funding_come_from

Note:
You are not attacking a Moderator, as I understand the definition of attack.
Attack requires a violent and/or personal component.
You are expressing a differing opinion.

I disagree with your broad statement that it is safe on all vehicles.
Concours d'Elegance: restoration shops that I know, would terminate employment, and sue for damage, if you lifted a Rolls-Royce or Bentley by the differential, lifting a Rolls-Royce Silver Shadow by the differential wrecks the sub frame no exception to this fact = $3,800.00 USD damage.

Please consider that many of these cars are ten, twenty-five or more years old, this can mean serious corrosion in structural areas, what was acceptable on a NEW car will damage or destroy a rusty old car.

I paid $75 for my new diff mount last fall and after looking over it I decided I didn't want to risk damaging the rubber. So since it is extremly easy to slip the jack under the rear sub frame I jack it from their.

I posted the question over on MB.org, (Mercedes Digest, Vol 2, Issue 127)

Der Diesel Doktor sez.... "Absolutely ok with cars with dual half axles"

Ok Whunter ,what i meant is all MB ,an ok if you are dealing with concours cars than i would maybe try and find a different spot.But nobody sayed anythink about show cars.It was just asked where to lift typical cars,for fast and easy raising of a vehicle or that is what i got out of the question.Most cars like 123,124,126,129 the diffs are made out of cast iron,so they are reallly sturdy and they weigh about 50lbs.So they are strong enough to withstand the weight of the vehicle.

For my shop work, mostly repair and maintenance on my own 3 cars, I invested a whopping $40.00 or so for 2 WalMart cheapo floor jacks. To raise the rear of my 380SE, and my Mazda 929 (which BTW has the same rear end setup, bushings, subframe and all), I position the jack pads under the rear subframe bushings, and position each jack stand under the adjacent subframe arm. I let the weight down on the stands and leave the jacks in raised in place. I found that the differential is too awkward to use when trying to pump up the floorjack.