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Rear Ride Height

11K views 47 replies 12 participants last post by  Will W140 
#1 ·
Hello,

I had an interesting thought while viewing my neighbor's S600 as it sat at the dealer for a service (I happened to swing by to order the recirculation filter). His car seemed to sit lower in the back compared to mine - though his may have been sitting for a little while. I think it may have something to do with the ADS, and it may elaborate upon some of the difficulties Chris and I have had with our systems.

So, if you will, please post a picture of your rear ride height, at a 90 degree angle on flat ground if you have ADS, for comparison!

 
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#4 ·
Stock size, 235/60 I think?

Chris, do you have a link on how to do it? V12uberalles has something similar but the pictures are gone in the web archive so it's not very useful.
 
#6 ·
Chris, do you have a link on how to do it? V12uberalles has something similar but the pictures are gone in the web archive so it's not very useful.
The site was recently resurrected and the extension now is .org
Please update your bookmarks.

I also have pictures in my threads, for example:



Moving the lever up/down changes the height. Mark the current position and plat with it, just be safe and don't get crushed under the car (and watch for your fingers).

Good luck,
Steve

PS Just checked -- Brett's instruction and photos do load up:
http://v12uberalles.org/Self-Leveling_Valve/Self-Leveling_Valve.html?i=1
 
#8 ·
Unfortunately some of those picture links are broken on my end, but it is a simple enough thing to adjust the control arm. The tricky should be obvious from Brett's article, you don't have very much room to work. Steve's point is also true, don't get crushed!

Anyway, here's my current ride height, which I always felt was a little too low. Forgive the slight dirtiness, I need to do some detailing. :p

 
#9 ·
Unfortunately some of those picture links are broken on my end, but it is a simple enough thing to adjust the control arm.
Chris:
It is never that simple. I attach a PDF just created from the V12's page and some other official MB documents on the subject


Anyway, here's my current ride height, which I always felt was a little too low.
It does seem a bit low, but there was a measurement chart which I cannot find right now. MB gives you the factory ride height in mm, measured from the center of the star on the wheel to the wheel arch.

There were several different values, and IIRC the early coupe was supposed to be a tad higher than the sedan. Does anyone have those numbers?

Steve
 

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#11 ·
#12 ·
Our definitions of simple must differ, Steve.
Hi Chris:
One of the documents I attached earlier refers you MB 40-0310. Did you see it?
If not, please download it here:

http://www.w124performance.com/service/w124CD2/Program/Chassis/40-0310.pdf

This is simple, really...?

:))

I am sure those number were somewhere in the archives, but searching for "ride height" returns sooo many hits.....

Steve
That link solved how to fix this. Thanks for that. It appears when the new one was installed a few months back, it was adjusted with no load - or in the air. Now to decide on how much to lower it....(probably down to where it was when I got the car).
 
#13 ·
As a side note, it does seem simple to me if you're just adjusting a little up or down rather than going through the loading process. The prescribed height is optimal but playing around a little never hurt. And....hey. I never completely follow the instructions.
 
#14 ·
Well, folks, I can pretty easily conclude my suspension issues here.

One: The height was set to around 3/5-2/3 biased right from center, on the rod. I put it at 3/4 to the left at first, then adjusted to 2/3 after a short test. The ride quality is MUCH improved. I believe a strong bias to either side would be detrimental. Chris, take notice.

Two: My brand new SLS valve (something replaced along with my shocks a few months ago) was -not- secured to the sway bar. Yes, you read that correctly. The threaded part (supposedly hell to remove) was already conveniently missing the nut holding it on, and it was free-floating in its hole. I called the shop I had put in these components and he told me that I shouldn't be messing with the height and that the valve didn't need that nut. Well, he's good at doing stuff I don't want to, so I feigned agreement and hung up. On my way to a hardware store to get a nut.
 
#48 ·
Well, folks, I can pretty easily conclude my suspension issues here.

One: The height was set to around 3/5-2/3 biased right from center, on the rod. I put it at 3/4 to the left at first, then adjusted to 2/3 after a short test. The ride quality is MUCH improved. I believe a strong bias to either side would be detrimental. Chris, take notice.

Two: My brand new SLS valve (something replaced along with my shocks a few months ago) was -not- secured to the sway bar. Yes, you read that correctly. The threaded part (supposedly hell to remove) was already conveniently missing the nut holding it on, and it was free-floating in its hole. I called the shop I had put in these components and he told me that I shouldn't be messing with the height and that the valve didn't need that nut. Well, he's good at doing stuff I don't want to, so I feigned agreement and hung up. On my way to a hardware store to get a nut.
Hey not sure if you’ll see this message, but when I read your response about replacing the self leveling valve along with your rear struts, what was the main reason for replacing the self leveling valve? I bought one recently and I’m going to have it installed by my mechanic along with accumulators, fluid, lower rear strut mounts, etc. In your opinion, what are the benefit of replacing the leveling valve?

One thing that I have noticed is that my ride quality is variable. Sometimes the vehicle rides perfectly, sometimes it rides very rough. And I’ve noticed that it seems to be attributed to when the self leveling system is functioning properly. What I mean is I’ve noticed that when the vehicle is riding very smoothly and then I press on the rear end of the car I will feel it pushing back up against me. And when the vehicle is riding lousy, and I put weight on the rear, it will not be pushing up against me meaning that the self leveling system is not working at that time. It must have something to do with where the fluid is being directed and I’m assuming that’s why people replace the self leveling valve. Does that sound at all correct?
If anybody has any knowledge or experience with what I’m trying to explain. Please please let me know!
 
#16 · (Edited)
I'll have to try and find that measurement chart myself, something like that would be very useful when I get around to adjusting my SLS. If anyone has it, post it please!
Chris:
I've been searching for the past 1.5 days to no avail.
Found this, which could be of use -- several dimensions (front and back) that could be used to estimate to the factory designed ride height.

Good luck,
Steve

EDIT: the moderators may not like it, but this picture came from here
 

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#19 ·
james sharp; said:
how does the height setting influence ride quality?
The shocks will work best if they are at the "sweet-spot" for doing they damping job. If you think about it, the piston inside will have a limited travel if the car is sitting too high (overextended) or too low (overcompressed).

Of course, one should also want to factor in the suspension geometry, which changes as a function of the ride height.
Therefore the camber setting is given at very specific vehicle height.

A good alignment shop will make sure you don't have extra 100 lbs of stuff in the trunk and will check/inflate tires before checking the angles.

Hope this helps with your question.
Steve
 
#21 ·
Steve,

No biggie on your info. I get links from other sites, but do not try at peach parts, or mention other vendor links, and they will erase your post with no nothing.

Mr. Ark Latex,

I adjust the lever until it looks good.. These cars will always require a tweak every so often, and east coast cars with the road salt can weaken the lever from rust...

Martin
 
#22 · (Edited)
My W140 S500 rear suspension has never felt quite right. It has always felt crashy/harsh and poorly damped in the rear. Since I bought it, I’ve replaced both accumulators, replaced the ride height adjustment linkage (old one was rusted/seized so I couldn’t adjust), flushed/replaced the SLS hydraulic oil, and replaced worn rear lower control arm bushings. Unfortunately, none of these things have had much of an effect on ride quality. My old W126 300SE with conventional suspension rode much better, and honestly even a Toyota Corolla feels much better over bumps than my W140.

The only thing that has had a noticeable effect on rear ride quality of my W140 has been the SLS ride height adjustment. Raising the rear a little (such that the rear jack point was 3-4 mm higher than the front Jack point) made the car ride a bit better, but still noticeably worse than a Corolla. Raising the rear such that the rear jack point was 30 mm higher than the front jack point made the car ride acceptably (at least not much worse than a Corolla, but not impressively smooth either), but it was looking funny with the rear jacked up so high. Setting a “normal” ride height where the front and rear jack points are the same height (bottom of car is level when unloaded) resulted in a poor and crashy ride.

At least when the car is not moving, with the car at a normal/level looking ride height, the suspension feels decently soft in the rear when I put my weight on it, much softer sprung than a Corolla or Camry, and almost as soft as my W126’s rear springs felt. I don’t get why the car’s rear ride and damping feel so rubbish when I’m moving.

Is ride quality supposed to be this dependent on ride height? Any idea why my car rides harsher than a Corolla?
 
#24 ·
Hey Wizee,

With these symptoms it is highly likely that there is too much hydraulic fluid in your system. Extract some of the fluid. There is an “official” procedure for setting the correct amount of fluid, however YMMV as to its efficacy on ride quality. In my experience lowering a little bit below that point gives a better ride (again, YMMV).

Raising the rear above nominal “correct” height has never led to better ride quality under normal circumstances on my cars, so it’s definitely got something wrong.
 
#27 ·
I checked my SLS reservoir, and at normal ride height it was overfilled by around 100 ml, so I sucked out that much fluid. Sucking out the excess fluid didn't have any noticeable impact on the damping though, as I expected.

I noticed the fluid I sucked out was rather dark for my liking - I'm guessing my mechanic who flushed the hydraulic oil didn't play with the ride height while flushing, so stale fluid was left over in the struts and accumulators, and then that stale stuff intermixed when we later played with ride height.

Could it be that the dirty and stale old fluid in the accumulators and shocks from god knows when was the wrong viscosity, and that raising the rear brought fresh low viscosity fluid into the line and spheres, softening the damping? Lowering the ride height back to normal made the damping harsh again.

Maybe I should lower the ride height adjustment all the way down, then flush the system to try to get most of the old oil out, then raise it back to normal ride height.
 
#29 ·
In my experience, some old fluid remaining after a change doesn’t have a major impact on ride quality. Though, I also doubt it’d really show up in the reservoir - it’s possible that the fluid wasn’t changed at all, but was drain & filled.

How many miles are on your car? With over 100k, the bushings everywhere are ready to be replaced.
 
#33 ·
Oh, this is entirely my mistake - I assumed you had ADS. The SLS-alone system is quite different, if I recall. I can’t really help you out then.
 
#34 ·
The SLS system doesn't have the variable damping solenoid valves, and the front suspension is fully conventional with fixed dampers. The rear ride height is controlled by a levelling valve actuated by a mechanical linkage attached to the suspension. No electronics or sensors in the SLS system. The SLS rear ride height adjustment and self levelling works mostly the same as ADS (at least ADS I, not sure about ADS II). The level of damping is affected by fluid viscosity; the ZH-M fluid (same used by ADS) should have the correct viscosity for SLS to feel right.

Maybe at some point in the car's history someone put in some different hydraulic fluid - I don't know. Maybe some of the potentially wrong viscosity stuff is left over in the struts and accumulator spheres. That's my current guess as to why damping is harsh. I can't think of any other explanation.
 
#35 ·
Any noise from your upper rear shock tower mounts? Mine were shot and gave a clunk and rattle at about shoulder height. I cant say if it really changed the ride quality, but it was extremely distracting and instantly noticeable when i pulled the shocks, and completely gone after i put new ones on.
 
#36 ·
I don't think so but I'm not sure. I'll inspect them when I have a chance. Going over sharp bumps in the road, the rear damping feels 3x stiffer than the front, and the harsh impact causes the whole car's rear structure to shudder loudly. At a standstill, pushing down on the car, the front springs feel much firmer than the rears, as I would expect. However, when moving, the rear feels severely overdamped over sharp bumps/cracks/dips/potholes.

When I had the rear of the car set to a high ride height, damping felt softer/better (I'm guessing because fresh proper viscosity oil flowed into the dampers), though the overall effective spring rate felt higher when pushing down on the rear of the car. After lowering the rear back to normal ride height, rear damping became harsh again.
 
#37 ·
Way Way WAY too high front AND rear. Mine was too high too, and felt like it was riding on bricks. Hydraulic system spewed like a keg of hot beer when opened up. You have too much fluid else the system wasn't properly bled when last done and has air/foam. Easy mistake. My coupe is supple but firm on 18s after correcting ride height with lever AND fluid.

No real manual on how to set height - I bought original product brochures from US and Europe to look at new car photos and discern the proper height - it is lower than you think, with not much "visual" clearance standing beside the car at adult height and looking at the wheel wells. Maybe an inch. My coupe 18s literally tuck just barely under the rear fender visually. You will have more visual space on 16s with 235s, but you car is easily between 1 and 2 inches too high and that WILL absolutely kill ide quality. Not enough suspension travel as it's distended.

Your car looks LEVEL, which is what you want, but too high.
 
#38 ·
The MB spec for ride height involved measurement of angle of the axis of the drive axles. Unfortunately MB didn't make spec in terms of angle, but instead in terms of gradations on a plumb line 'beam' type special tool. Not helpful for posterity.

For SLS/ADS system the drive axles are almost horizontal in the laden (wheels on the ground) state.

The deviation from horizontal (angle) with the outer ends of the drive axles slightly down is a very small amount; 1/4 or less of that for the 'standard' suspension. I'd shoot for angle of 0.00°.

A little electronic level on the drive axles in the back would be one way to show if you're way off in leveling valve 'control point' setting. Unfortunately, you need a pit or ramps in the back and then jack up front till vehicle is level under the rocker panels.


Get the rear right first, then set the front to agree with the rear.

Having cited the electronic level approach, I should say that I never used it but I did use ramps and 6 or more iterations of adjustment.

Getting the leveling valve set 'correctly' is a bit of a pain when the set point adjustment has been altered without marking the initial position. That's usually where/how the trouble starts.
 
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