lifting, jacking, supporting 123 chassis - Page 2 - PeachParts Mercedes-Benz Forum

Brian Carlton · #16 08-02-2004, 02:03 PM

Greg,

I'm not concerned with supporting 1800 lb. with the differential. A static load of that amount, for a short period of time is surely not going to poke a hole in the bottom of the vehicle.

The shocks absolutely do limit the travel. But, with the shocks fully extended, the wheels are sitting about seven inches lower than the "third member". This results in very high half shaft angles. Could this damage the half shafts, or the third member, in some way? It certainly makes a crunch of the rubber boots, that's for sure.

leathermang · #17 08-02-2004, 02:34 PM

With a normal rear end... if you jack up the third member the force goes to the springs and to the normal places on the frame made to support the weight of the car... but not so on our cars...
So I would worry about it...

On the high angles when jacked up... keep the indicated speed on the speedo under 50....

#18 08-02-2004, 02:34 PM

On the 124 car you DEFINITELY do not want to lift the rear by the diff. There are very hard to replace rubber mounts that will eventually be ruined by this practice. Don't ask how I know that.

On the 123 car, however, I have raised them at the very least, a 100 times with no ill effect.

Brians first suggestion of lifting the front by crossmember behind the lower oil pan and the rear by the diff worked great for me in my 123 days.

For supporting the front with jack stands, put them under the portion that looks like rectangular tubing that curves upward toward the firewall. I don't remember ever supporting the rear with jack stands although I'm sure that I did. I would not feel comfortable on the subframe mounts. I don't remember if there are rubber supports under the rear of a 123 as there are on the 124.

I have a good memory, but it's just too short.

Good luck,

Wes Bender · #19 08-02-2004, 04:50 PM

Good post, Eskimo

I did the same search a few weeks ago (with the same results). I eventually did approximately what LarryBible describes.

The angles achieved, however, caused me to take the car up in two stages to keep the jackstands from slipping. I used blocks to keep from damaging anything on the 300D.

Those inserts for the normal jack points are intriguing (and probably made out of unobtainium).

Wes

Old300D · #20 08-02-2004, 05:13 PM

I'm new to these cars, but I have been jacking the rear of my W123 by the differential, just like I've done for years with my Datsun 280Z (independent rear drive). And I've been putting my jackstands under the lower arms, either at the pivot points or near the wheels. It seems stable enough, and I don't believe I've bent or broken anything yet...

DieselAddict · #21 08-02-2004, 05:44 PM

My W124 rear mounts were ruined by a tire shop that probably jacked up the car by the rear. However they were already quite worn prior to this and I think this tire change was the last straw. I once saw a tire shop jack up one of my W123's by the rear and fortunately no apparent damage occured, but I think next time I'll tell them not to do that again.

When I lift one of my cars I either drive it onto my Rhino ramps or jack up the front or rear with the Mercedes jack and support it with jack stands with small wooden blocks right under the jacking holes. However I haven't found a safe, cost-effective way of lifting the entire car.

rs899 · #22 08-02-2004, 06:05 PM

The differential or third member is bolted ridgidly and directly to the subframe and the subframe is secured to the body by the two front subframe mounts and the diff mount in the rear. I wasn't too concerned with jacking under my diff because my mounts are all new (as of two weeks ago) and my subframe is pristine but its pretty heavy back there. I wouldn't think jacking for a minute while you get jackstands under the sills would do much harm, but I wouldn't leave the jack there long.

I have a two-post lift but its always occupied. I leave my 70 Spitfire permanently up in the air over my 240D and its a bit of a chore moving all that iron (particularly when the British piece doesn't want to start).

A lift is a good solution for some operations (for example) rebushing the driveline), but not for others (subframe, shocks) that require support from below or removal of a heavy object that could shift balance.

CarolinaMBZ · #23 08-03-2004, 11:54 AM

Old300D: Just a thought, my 76 280Z along with about everybody else's with whom I am familiar has or has had a "loose" rear-end (some to the point of banging on shifts despite smooth clutch work). These cars were one of the first independent rear end cars where "joe at the corner garage" would have had a chance to lift it by its diff. (Beating the hell out of them didn't help either). My rear end mounts were replaced on my Z back in 1987 and the solid drive train feeling returned. Lifting by the diff won't kill the rigidity of the mounts instantly but I believe that it will certainly accelerate their loss of rigidity which will be noticed somewhere "down-the-road." I have also had this issue on my 300E's and my 240D suffers a little from this as well (prior owner's tenure issues).

Old300D · #24 08-03-2004, 12:07 PM

Quote:

Originally posted by CarolinaMBZ
Old300D: Just a thought, my 76 280Z along with about everybody else's with whom I am famaliar has or has had a "loose" rear-end (some to the point of banging on shifts despite smooth clutch work). These cars were one of the first independent rear end cars where "joe at the corner garage" would have had a chance to lift it by its diff. (Beating the hell out of them didn't help either). My rear end mounts were replaced on my Z back in 1987 and the solid drive train feeling returned. Lifting by the diff won't kill the rigidity of the mounts instantly but I believe that it will certainly accelerate their loss of rigidity which will be noticed somewhere "down-the-road." I have also had this issue on my 300E's and my 240D suffers a little from this as well (prior owner's tenure issues).

You might say I have been intimately involved with my 280Z. The mustache bar solidly connects the rear pumpkin to the unibody, and those bushings are polyurethane. The front mount has been anchored solidly to help stick those 1.9 second 60' launches - I drag race the thing. So I am totally confident of lifting that car by the diff. I'm going to look at my 240D again - it needs new mounts, and I should replace the diff with a 3.07 from a turbo anyway...

CarolinaMBZ · #25 08-03-2004, 12:44 PM

Old300D: What kind of power are you running in that thing? I don't see any harm if your using polyurethane, in fact it ought to be bulletproof. That stuff is unbreakable from what I understand. Even suspension bushes last forever, although I understand that its your dentist that really benefits though when poly is used in your suspension as he gets to replace all your fillings over and over.

On dropping a taller rearend in the 240D, I need to do that too. If and when you do it I sure would like to know how it goes.

Old300D · #26 08-03-2004, 12:49 PM

Quote:

Originally posted by CarolinaMBZ
Old300D: What kind of power are you running in that thing? I don't see any harm if your using polyurethane, in fact it ought to be bulletproof. That stuff is unbreakable from what I understand. Even suspension bushes last forever, although I understand that its your dentist that really benefits though when poly is used in your suspension as he gets to replace all your fillings over and over.

On dropping a taller rearend in the 240D, I need to do that to. If and when you do it I sure would like to know how it goes.

I dyno'd 313 rwhp and 419 ft-lbs torque (corrected to sea level). And it does ride a bit rough with poly bushings all around, but it still has factory sway bars, 60 series tires and progressive rate springs - it's not too bad.

CarolinaMBZ · #27 08-03-2004, 12:54 PM

We're off topic, so I'll pm you.

Eskimo · #28 08-15-2004, 12:04 AM

I put some of them into practice tonight for my first oil change on the '85 300D.

I lifted from the front crossmember, and then put stands under the front jacking points. I ended up indulging in a new pair of jack stands with "flat top" posts with rubber pads, and they seemed to work just dandy.

Again, thanks.

-- eskimo

CarolinaMBZ · #29 08-16-2004, 08:34 AM

Eskimo: With a little practice and familiarity with the W123 chassis and the location of the oil plug, you will find that you can change the oil without lifting the car at all, just taking a knee and reaching under with a 13mm boxend wrench is all it takes.

The best way to learn these cars though, is to spend a little time under them. Glad you met with success.