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Old 05-09-2000, 09:32 AM
Posts: n/a
Here is a posting from Listers that explains what might be causing the sagging:


Date: Fri, 28 Apr 2000 11:48:59 -0500
From: Stuart Steele <>
Subject: RE: [MB] 126 rear shock & spring R&R DIY'er?

Hello, Christopher and List:

Alas, I have nothing of my own to offer, except that I know where to look! -
Stu Ritter has provided just about all that a person can know about this
subject in a few pithy posts, which I have copied below.

Stuart Steele

Christopher Wright asks:
> Rear end is sagging a bit. Is this a pretty good DIY'er?

>> here we follow with Stu Ritter's posts on the subject <<

Stu Ritter writes on 2/14/1998 10:03:00 AM, in a message entitled
"[MB] Sagging in the rear 126 chassis":

On the 126 chassis, the first place to look when the rear end is sagging
is the differential mount. The mount collapses internally and is very hard
to see. Most MB mechanics don't recognise this problem. The entire
rear subframe is mounted at three points. The two forward big rubber
mounts and the mount at the rear of the differential. When the differential
mount collapses it changes the rear ride height and the rear end sags.
It is a very rare case when springs sag on a Benz. It is almost always
the mounts (lone exception, my father-in-law's 300SE, of cource). I
think I have replaced two sets of rear springs in 27 years and hundreds
of rear differential mounts.
Gas shock absorbers do not control or maintain ride height. The purpose
of the gas in the shock is to prevent the oil from foaming when it gets hot
under hard usage. You can compress the shock with about 70 pounds of
push. That doesn't go very far in holding up a 1500 pound corner on a
3700 pound car.
Considering you have an 83 126 chassis, if the rear mounts have not been
done yet, I would replace both the rear subframe mounts and the differential
mount. You will be amazed at how the car will feel when this is done. It
will feel very new. As the rear rubber mounts collapse, over time, they
allow the rear wheels to start steering the car. It makes the car seem a
little nervous and darty. With new rubber mounts the car just settles down
and becomes very relaxing to drive..

Stu Ritter writes on 4/9/1998 12:17:00 PM, in a message entitled
"Re: [MB] [MB Digest]rear spring seats":

> Stu, my car, rear height, is too low. I measured the height at the
Did you measure the spring height before it was installed and compare
it with the height of the spring that was removed. Did you do the spring
replacement yourself?? When we did replace a set of rear springs, we
compared the uncompressed height of the spring from the car with the
new one and were surprised that the new one was about .5 inch lower.
We then put the springs on a scale and measured the distance compressed
for a given force and the taller, used springs moved three times as far
under the same weight as the new springs. We were sure the old ones
were collapsed and we were correct.
>>From the lower edge of the upper steel cup, down to the upper surface of
>trailing arm and parallel to the spring, I get 7.5 inches. Both sides.
>'81 300 SD measured 8.25 inches. One would conclude that the springs are
>short. These are new, OE springs.
My experience has been, on the whole, that: when the rear of the car
is sagging, both the rear subframe mounts and the differential mount
have collapsed into themselves and have altered the ride height.
I have only replaced one set of springs on a 126 chassis in the past
18 years and have replaced innumerable subframe and differential
mounts. 107's and 126's seem to show the degeneration of the sub-
frame mounts the most by sagging quite a bit. New mounts and they
just pop right back into place.

> The only parts I have not changed are the subframe mounts, left and
>They look good. Flexible and the rubber is black and glossy.
> I guess I could put a thicker seat in, if available. That is like
>the springs out all over again, though.
> Any thoughts?
> Much appreciated.
> Rick Hesek
as above...the rear mounts..

Stu Ritter writes on 1/13/1999 7:40:00 AM, in a message entitled
"[MB] How low is too low?":

All measurements of the chassis and all height adjustments are done
with the engine off. If engine torque load is causing the rear end to
sag, there is a good chance that the rubber mounts for the rear
subframe and the rubber mount for the differential are sagged and
should be replaced. You car is 9 years old and Manilla is quite hot
if I remember. I would think that the rubber mounts (which help
determine rear axle position and therefore ride height) have served
their time and could be replaced. This will probably help..

Stu Ritter writes on 1/13/1999 11:50:00 AM, in a message entitled
"Re: [MB] How low is too low?":

>Thank you for your reply. I will check the subframe and differential
>mount first thing in the morning. Stu, My previous investigation shows
>that there are three pieces of rubber mount stack together on the subframe,
>is it okay to add one more?
The rear subframe mounts are one-piece mounts. You cannot "stack"
anything else in to change the ride height. That is determined by the
spring height. The engine does not have enough torque to compress
the springs..more than likely, the rubber is compressing and allowing
the ride height change.
I also forgot to mentioned that when in
>Reverse, the rear will suddenly rise by couple of inches. One more thing,
>ride height is okay when engine is shut off, however, when there are one
>two passengers at the back, the car's rear will sag significantly, more so
>when it is on drive. Are the springs and shock absorbers due for
The shock absorbers do not affect the ride all..
The only way to check the spring is to remove it, compress it with
a known force and measure the distance and compare that to the
manual. I have known one other 300SE 1989 model year that had
sagging rear springs that we replaced. Normally a Benz never needs

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