I've been working on the problem of the low ride height in the back of the SDL for the past several months.

All dimensions will be made from the road to the inside of the fenderwell in the back.

Prior to any modifications, the vehicle would typically have a ride height of 24.50-24.75 inches. This is a pronounced squat in the back.

I changed subframe bushings and differential mount. This increased ride height to 25.50 inches. A small improvement, but not enough.

Then, last Thursday, I changed rear springs. The ride height increased from 25.5 to 27.50 as soon as the vehicle came off the jacks. The camber on the rear wheels went from 1" negative (measured on the tires) to about 1/4" positive. So far so good. I am assuming that it will settle down a bit.

It sat for three days, without moving the vehicle, and the ride height eased down to 27.25". The vehicle looks about perfect.

I take it for a ride for the first time yesterday. 100 miles.

It looked a bit funny at the midpoint of the ride, but, I had no tape measure.

Measured the ride height this morning:25.5"
Camber: 1" negative

So, does anybody have any possible reasons of how the rear suspension can compress by 1.75" by simply taking it for a drive? If I didn't see it myself, I would not have believed it. It seems almost impossible. What can allow the body to drop by his huge amount???

The springs are German and manufactured by Meyle.

I'm baffled by this. It almost seems like the springs are defective. But, I can't fathom how a test drive would cause the springs to compress more than they did after three days of sitting in the driveway??

I'm now quite frustrated by this whole deal. Nearly $300. in the back end and hardly any improvement as compared to where I started.

I think that the wire size used may be the cause of this..
How does the size of the new compare to the old ? Mercedes is very particular about this... making the springs and THEN measureing and classifying them....

Brian, is there any way that the springs could have rotated in their seats during that 100 mile drive. If they could, they would -

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

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

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

I don't think they can, Pete. They are under some huge friction loads. Once you place them, that's where they are going to live. They contact a rubber pad on the top and the friction is very high.

Did you measure the height immediatlt after lowering the jack...or did you move the car back and forth to let it settle...why? off the ground the track will be narrower than it will loaded..it will bee restricted from settleing by the tires inablilty to slide outwards to meet equi;librium....thats the nature of a independent rear suspension...or the front one too.....straight off the jack is not an accurate measurement.

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Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

Ok, that explains the increased height when it came off the jack. I did not move it back or forth, whatsoever, in the three days that it was sitting there.

So, the measurement off the jack, 27.25", is not relevant.

Thanks for the clarification.

I agree with Pete also...unless there is a physical stop keeping the end of a spring from moving it is certainly possible for them to rotate.... they are just using the ramp model of trying to escape their load... and they will follow ' down hill' if they can... this is particularly true with the constant aggravation of movement which a suspension experiences.
But you need to measure the spring wire size...

"....straight off the jack is not an accurate measurement."

Thus the reason for having to move the car forward to measure and set the toe in accurately...tires can hold a lot of kenetic potential...from getting to the suspension...

The lower spring perch has a slight shape to it. The very end of the last coil is designed to rest against a small stop in a bit of a depression. For the spring to rotate, it would have to rotate "uphill". This is not likely. If it did happen, the ride height would increase.

I'll probably put it up on a jack and take a look around, but, I'm not optimistic about it.

Oh, I know the friction is very high, but so is the vector seeking rotation, and I think that rubber is more resistant to compression than torsion. That's the only thing that comes to (small) mind here .

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

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

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

On cursory inspection (no hard data) the wire appears to be identical.

How can the spring sit for three days under load and then give up 1.75" after working it, unless it is defective? Two defective springs?

I have a 82 300D and it had a 2" sag in the back. I went to the dealer and got the thickest rubber spring pads I could 19mm. so removed the springs and put the rubber in,and reinstalled it . the car was only 1/2 inch higher so I got a set of stationwagon springs and tried that still the same hight. then I went to pepboys auto and got the 1950's fix for $7.00 thay are a set of 4 spring spreaders. it's a sqiare block with a machined ramp in a spiral across the face. the block is only about 2 inches wide and you jack up the car and tap it in between a coil near the top and use a 1/2 inch ratchet to screw it in. I only used 1 on each side then let the car down. it satup exactly the same as the front and its been the same
height for 2 months now and did not change the ride of the car at all.

in my experience those type of blocks did affect ride negatively. in addition to making it stiffer it limits the normal travel some.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Brian, i have a 85 300D and want to replace the springs and shocks all they way around. i know you had purchased custom springs for your SDL, but can you help me find the right measurements for my car. i want to order them also, but am not an expert when it comes to the degree's and chamber. what height do you recommend i get so that the rear does not sag.

thanks,

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Grey '91 350SDL 214k Dad's car
Beige '81 240D 4 Speed 254k SOLD
Blue '82 300D 225k SOLD
White '95 E300D 46k SOLD
Blue '87 190D 2.5 Turbo 315k SOLD
Brown '80 240D 4 Speed 716k SOLD
Beige '80 300D N/A 119k SOLD
Blue '85 300D Model 186k T-Boned

With the W123, I don't believe that there should be any difficulty with the stock replacement springs. The need to go to the custom springs, IMHO, was simply due to the fact that the extended body of the W126 will sag with a moderate load in the trunk......even with brand new springs. So, I simply decided to get slightly longer springs and be done with it.

How do you know the springs are bad?

Usually, that body does not abuse it's springs at all. Shocks and differential mount will raise the body at least one inch in the rear.

I just replaced the rear shocks on the SD. Totally shot. No gas resistance whatsoever.

PM me for the source for shocks if you don't already know.