I've got several boxes of new control arms waiting to be installed in the rear suspension of my 1987 300D. I'm clearly going to have to get both rear wheels off the ground for this, and I have searched around for best practices and come up some admonitions not to jack under the diff, but haven't been seen anything WRT where I -should- jack.

So, where should I jack?

For support, I was planning to put jack stands under the pads at the jacking ports. I trust this is kosher.

Any other tips from those in the know?

Thanks!

Pretty please? Is this common knowledge or a question without a good answer?

I don't know the 124, but this should be OK, as long as car is on a hard surface and front wheels are ABSOLUTELY chocked. After the jacks are set and before you go under, give the car a good shaking like your life depends upon it, because it does!

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

Drive the rear wheel up on a couple of short lengths of 2X6 boards stacked 2 high. This will give you enough room to place a bottle jack under each pad. I use a 3"X3"X3/4"piece of oak between rubber pad and jack, or, place a ramp under each of the four wheels, and drive it up. This should give you enough room to crawl under the whole car.

Ramps are by far my preference when working under a car, but the rear wheels are going to have to come off for this operation..

That's what's giving me fits, since I need to lift both sides at once and set it down on a pair of stands without doing something potentially damaging.

The car came with a Class II trailer hitch installed. IIRC the tongue weight is not to exceed 750 lbs, but is there some way I can safely utilize it as a center-line jacking point?

why on earth would you have to lift both sides at the same time? Do one, then the other.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

If I use the factory jack to put one side on a stand high enough to work under, then, when I lift the other side, won't the geometry of things change enough to put a bit of a sideload on the jackstand already placed?

I suppose I could put the rear on ramps first, but I'm not sure what the max extension of the factory jack is.

Sounds like I might be more paranoid about putting a car on stands than you are.

I explained how to utilize the rubber pads under each of the 4 jack holes. It's not rocket science, or theory, I've done this many many times, and it works every time!

Are you suggesting working under the car while it's supported by bottle jacks? Sorry if I misunderstood.

Simply go buy a floor jack, or maybe 2. They are not much. Got my two at Sears. You can safely jack under the rubber pads , but you need to put a shim in the jack pad so that the rubber pad doesn't drop in too far and damage the lower cladding. I have heard that a hockey puck works well.

You can also use the floor jack under the differential, but it tough to get to
if you only have on floor jack. Use jack stands for further safety.

I'm not arguing with bottle jack approach, but to me the base of a bottle jack is no where near as stable as a floor jack.

Steve

I will not work under a car unless it is supported by the tires or jack stand. I have a 3 ton pair and a 5 ton pair. They have a wide footprint at the base and an adjustable, cast iron cradle on the top. Also, I usually use a redundant support with a rolling floor jack, set to just bear a few pounds at a third point. Believe me, I'm as paranoid as the next guy - what did he say about me??

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

I really appreciate all the responses. I'm still stuck on the issue of what to do when my jacking points and my jackstand points are the same points.

The wheels have to be removed for this operation, per the service manual, so I can't put it on ramps.

Like Pete, I'm particular about the conditions under which I'll make a concrete-me-car sandwich.

Since my garage priviledges are being revoked at the end of the month, I'm just gonna have to get out there and make something work. I'll report back and let y'all know what I broke.

I wasn't suggesting you use a bottle jack to support the car while working on it. I was suggesting how to raise the car while you add additional support.

I always throw the tire I removed under the car (just forward from the pad, or as close to) while jacking higher in case the jack slips the car will fall on the tire.

You could put on top that wheel a tire without a rim, and some shims, and lower the car on to that, both sides. If careful, the load wont harm the underclading.

You are looking for alternative ways of supporting the car, but yes, a floor jack would be best to lift, but if careful, a bottle jack can work too. Ideally, this job is done best at a repair garage with car lift utilizing the four point (pads) lifts, but in your case, you need to support the car in two locations at each corner of the car.