How do I adjust rear ride height and what tools are necessary?

While wer're on it, how exactly does the sls work?

You've got the hydraulic fluid operating a level controller attached to the sway bar but then you also have hydraulic shocks...does the hydraulic fluid supply both the level controller and the shocks and to what effect?

shawnster,

This info pertains to the rear hydraulic suspension not the 4 corner hydraulic suspensions (rare).
1) The rear springs support the vehicle when unladen
2) The sls is only utilized when weight is added to the wagon.
3) Raising the rear of the vehicle with the control linkage
will shorten the life of the accumulators.
4) If the rear is low, springs and or bump pads are needed.
5) When the control rod is properly adjusted a pin can be
inserted thru the actuator arm into the control valve.

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Paul

I had new shock mounts/bushings replaced about a week ago. Mechanic said that he "flushed and refilled" the hydraulic fluid but that I'd have to handle re-adjusting ride height.

It's quite a bit lower than previous to the work.

Is it possible that it requires bleeding air out using the bleed screw?

Would I do the following:
loosen the screws on the turnbuckle on the torsion bar, then
insert a pin or small screwdriver through the lever and into the hole on the side of the controller body, then
tighten the screws on the turnbuckle.

or do I shorten or lengthen the lever?
how do I pop off the lever on either side?

chicken vs. egg routine here:
if i would remove the controller lever and never do another thing with it, the car, while unloaded, should be at "normal" height which is maintained by the shocks and springs.

its NOT that the level controller applies force to the torsion bar to change or maintain ride height.

it IS the additional weight of a load pushing down on the torsion bar which activates the lever controller to pump more fluid into the shocks and therefore adjusts for load.


Am I right? (please tell me I'm right)

shawnster,
Now you understand

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Paul

OK, here's the deal. Both very soft and very hard rides can result from failed accumlators, the suspension should be the finest in the world, no holds barred, it should be firm but smoothe, absorb bumps silently and smoothly, keep a level vehicle regardless of weight and you should be able to run over a brick with just one rear wheel, going around a corner and still cut a diamond in the back seat... OK a bit extreme but not far off.

First you need to know how the system works. You have a belt driven hydralic pump, the pressurized fluid passes through a line to the leveling valve. This valve has an actuating lever attached via an adjustable rod to the sway bar. When the rear of the car is depressed, the valve opens and forces fluid through the accumulators and into the "Shocks" which are actually hydralic rams, these raise the car until the lever is again level and valve closes. The accumulators simply absorb the shocks with compressed gas. Now look at each seperate system.

Leveling. Since the "shocks" are simply rams which raise the vehicle, and fluids do not compress this system is very hard without the accumulators. To check the system, shut the vehicle off, measure from the ground to the wheel arch and write it down. Now place weight in the rear, try opening the trunk and having two people sit on the rear. Measure the didtance again, it should be less with the weight. Now with the weight still in place start the engine and run it at about 1500 rpm for a minute or two...The rear should raise to the original level, if it does not, there is a problem - regardless of the accumulators.

Next raise the vehicle and look at the valve, it has a lever with an adjustable rod connected to it, the other end of the rod connects to an arm attached to the sway bar with a clamp (this clamp can slip lowering the vehicle). Disconnect the rod from the lever on the valve and rotate the lever upward to about 45 degrees. Lower the vehicle to the ground and again run the engine at 1500rpm, as soon as you notice the rear begin to rise, shut the engine down (as not to hyper extend the leveling rams) - OK it it went up then the valve, pump and rams all work. If it did not go up then you need to go into the system more carefully - let me know and I can explain, but since this is rarely the issue I will skip ahead.

The rod can be adjusted by turning the center and shortneing or lengthening the rod. Each two turns shorter raises the vehicle about 1" each two turns longer lowers the vehicle about 1". Keep at it until you get it level and there you go.

Shock absorbtion. Since the leveling system is hydralic and fluids do not compress, if you hit a bump, it will feel like the rear is solid. So the fluid runs into a sphere which is devided by a membrane, on the other side of the membrane is gas presurized to about 1700psi, when the vehicle hits a bump the fluid is forced from the ram and down the line into the oil filled side of the accumulator and from there to the valve, which should be shut because the vehicle is level. The only place which can give is the gas filled side of the accumulator, which it does and just as rapidly the gas expands and forced the ram back to its original position - Just like in a gas filled shock absorber. Get it? the "shock" is actually just a ram which raises or lowers the rear end, the accumulator is actually the "shock"!

If you have a very hard rear end when driving, OR if the rear seems to "wollow" or be very soft on the road then most likely you have bad accumulators but don't take my word for it, test them. The simplest way I know is to unscrew the hose going from the accumulator to the "shock" - BE VERY CAREFUL - the fluid is under a lot of pressure and will spray abut a coffee cup of oil everywhere. With the line off slide a small punch into the end of the accumulator, it should go no more than about 1/2 inch in, if it goes 3 to 4 inches in, the diaphram is gone and the accumulator is worthless and must be replaced.

Do not simply gut the hydramatic system and replace it with springs and shocks, you would be replaceing a remarkable system with a very basic one. Once working you can load the car down and have a level ride, you have a system which works better than just about anything on the road and you have no shocks to go bad.

If you need more info let me know and I will help as much as I can. I have a 1989 560 SEL, looks and runs like new with just under 200k...With hydramatic suspension.

Chris

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1971 Porsche 911 Targa RSR rep.
1968 BMW R60/2
1981 BMW R80GS-PD, dual plugs, 1000cc jugs, 10 gal "Gaston" tank.
1982 BMW R80GS-PD, duplicate of above.
1988 Neoplan/Mercedes 40' Bus
2002 SLK32 AMG
2013 Smart Electric

Chris,

What tires' brand & type do you have in the 560SEL ? I have the Conti Contact CH95 on mine and they seem a little harsh.

I resolved the rough thump when traveling down a speed bump with newer rear shock bushings.

Any other things to be considered for the ride quality ? I've only been to a few 560's with worse suspension then mine so don't really know how good is a good suspension supposed to be.

cheers,
Frank.

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'86 560SEL | Silver Ext. / Blue Int. | 201K miles (Apr. 05) | 204K miles (Feb. 06)

What is wrong with your suspension???

What are the symptoms?? Be as specific as possible, ince the system is understood is is fairly easy to repair and no where near as expensive as it was in past years, perhaps I can help.

As for tires.... I have studs on right now and as soon as the weather lets up I will probably track down come 18" Monoblocks and maybe run mich's

I don't really want a Ghetto Sled or a Drag car, just a nice 4 door comfort car with enough power and no one does that like Mercedes. Personally, I think the 560SEL was the last of the great Mercedes (sure to catch flack for saying so), it was designed to set a hallmark for all other manufacturers, the styling is classic and refined, the build quality is second to none, at close to 300hp it has more than enough power for anyone over 25 driving on the street.

__________________
******************************
1971 Porsche 911 Targa RSR rep.
1968 BMW R60/2
1981 BMW R80GS-PD, dual plugs, 1000cc jugs, 10 gal "Gaston" tank.
1982 BMW R80GS-PD, duplicate of above.
1988 Neoplan/Mercedes 40' Bus
2002 SLK32 AMG
2013 Smart Electric

Shawnster,
"A rear end which is low in curb weight condition should never be set higher by adjusting the connecting rod of the level controller."
"Therefore, if the vehicle is too low in curb weight condition, corrections on rear springs are required."
Excerpts from 40-310 checking vehicle level on vehicles with rear level control.

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Paul

I first want to thank Chris for his great description of how to diagnose and adjust the self levelling system. That's really useful information!

I also want to disagree with him just a little. Replacing the self levelling system is not such a bad move if you can do it. Although the sls is pretty effective when you put a load in the car (I have a wagon), it does not optimize handling the way a good set of springs/shocks/sway bars and bushings can. I have never changed out an MB sls yet but I have done it on my BMW 735il. The results were great on my 735. It handles like a dream.

I was wondering, with all due respect to Chris, has anybody out there changed their rear sls over to standard springs and shocks. In looking at the rear of my 92 300TE, the problem I see is the shock mounts. The mounting brackets are kinda weird looking on the bottom and I don't know if you can find a Bilstein or Koni shock to fit. When my components do wear out I may make a switch. So if anybody has done this, I would really like to hear how you did it.

William H
92 300 TE

__________________
prop up the faith,
whutchens

Regarding switching to standard suspension...

For a SEL you can get all the required parts from a 420SEL with standard suspension, be sure to get the blockoff plate for the pump as well. There are several threads here, one called "adios self leveling suspension", I considered this before I repaired my system.

As far as ride... A 560SEL is a large car and weigh close to 4k, it was never designed to handle like a sports car and even with the addition of standard suspension it will be found wanting in the performance handeling department. I suppose if you lowered the car (lowering the CG will decrease roll), mounted low profile tires (less side wall = less flex), and beefed up the sway bars, you might be able to get the corning of an overweight hockey puck you desire, however, changing the front sway bar (heavy engine up front) would require a massive amount of work. I would suggest that if it is handeling you desire, you simply but a smaller 2 door car rather than a Luxury 4 door the size of a small battleship.

As far as the ease of converting a BMW compared to a Merc...Apples and oranges.

As I ask all my clients; What do you want to do with your car? If you want a performancee car look for a small 2 door with a low center of gravity, 50/50 weight distribution, 4 wheel disc brakes, few power accessories, good power to weight ratio, manual transmission, etc. If you want to carry a load, a pick-up of a station wagon depending on the size of load. If you want to carry people...How many? If you must carry 9 then buy a minivan (and don't come here for repairs), if you need to carry 3 kids+, buy a Mercedes wagon with the 3rd seat. If you NEED 4x4 then buy one, if you just "like the way they look" think about maintaining 2 sets of drive train and payng for the fuel for 2 cars.

I guess what I am sayine is this. Vehicles are tools, designed for a specific purpose (this the exception of the PT Cruiser) and trying to make a luxury sedan handle like a Porsche 914 (one of the best handeling track cars ever made), or trying to make a 914 handle like a 560 is a kind of foolish endevour. If you don't like the SLS, buy the bits from a 420SEL and be done with it, but if you imagine that you can make a 4000 pound car, 17 feet long with a 112in wheel base handle like a pocket rocket......

__________________
******************************
1971 Porsche 911 Targa RSR rep.
1968 BMW R60/2
1981 BMW R80GS-PD, dual plugs, 1000cc jugs, 10 gal "Gaston" tank.
1982 BMW R80GS-PD, duplicate of above.
1988 Neoplan/Mercedes 40' Bus
2002 SLK32 AMG
2013 Smart Electric

I want to partially agree again with Chris. You are not going to make a 560 SEL handle like a sports car. I am talking about my 300 TE wagon and the same thing applies; it's not going to handle like a sports car. Chris obviously knows what he is talking about in regard to working on MBs, so I'm not really wanting to argue this point too much.

What I am talking about is a good shock versus the "actuators" on the MBs. I just don't believe that the quality of damping provided by the actuators is equal to that provided by a HD Bilstein or an adjustable Koni. Perhaps I am wrong, but I think that I am right. However, Chris, don't worry I am sticking with what I have for now. My 300 TE is in beautiful condition with only 87k original miles and the self levelling system is in great shape. So, no modifications are currently in the works there.

By the way Chris, have you ever played around with any sway bar changes on your MBs? That's one thing I was considering doing at this point. I wanted to put a little beefier bars on both ends in order to lessen the roll of the chassis. I have done this with other cars and the result was that there was much less body roll without compromising ride comfort much at all. I have not yet quite figured out what the ideal ration between front and rear bar diameter should be, but hope to do so in the near future. The stock difference is about 14mm.

Whutchens

__________________
prop up the faith,
whutchens

Chris,

When I put in new Bilstein comfort in the front about two year ago, I realized that the ride quality in the front is much better than the rear - it had a hideous thump when going over a speed bump; not on the way up but on the way down - it felt like the rear tires just hit the road real hard, no matter how slow I was driving.

Read in some MB boards that on there has been a redesign of the rear upper shock bushings - I went ahead and changed them out (total cost is less than $20 since I did it myself - a banana job). All I could say is WOW!!! The SLS now eats all road imperfections for breakfast

It was not too long till I felt that the front suspension now becomes inferior comparing to the rear (yes, I'm anal ) In some road conditions I still feel the roughness in the steeringwheel - not much but enough to keep me annoyed. I've changed out the lower ball joints (torn rubber boots - joints had some slacks) but to no avail. Could it be the flex disc that's getting too old ? How feasible is it to change it out ?
or is there something else that I should check (any other bushings that could improve ride quality )?

Thanks,
Frank.

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'86 560SEL | Silver Ext. / Blue Int. | 201K miles (Apr. 05) | 204K miles (Feb. 06)

On my 560 SEL thr front sway bar is just about impossible to get out without taking the whole front end apart, but on MANY other cars I have changed to HD sway bars with excellent results. Sway bars, Eurothane bushings, upper and lower braces, rear braces, larger rims with low profiles, limited slip diffs, all these things will improve handeling depending on the application.

Strut braces and large rims with low profile tires seem to be abused today, fitted to every otherwise stock honda on the road along with exhaust tips the size of an oil drum wrapped in carbon fibre contact paper. What has happened to the car culture in this country???

Why run 22" rims with zero profile tires on a street driven car? Every time you change lanes and hit the "Dum-dum" bumps you bend a rim. Every time you pull into a Safeway you ding the air damn and oil pan. I get a few of these in my shop and I charge a half hour "rack fee" because we have to put the car on ramps just to get the lift arms under. I probably raise more cars than I lower - especially Porsches. You can't drive a car if you an't get a credit card under the air damn and if you hit a wallow in the road going around a corner the front tire bends the fender. Short of a track car I really do not see the advantage? Are people really worried that an air cushion will develop under the car while commuting in heavy traffic and flip the car? Do they really pull 6g turns pulling into blockbuster video?

How about the trent to put 4" exhaust on a stock engine? Can you say "no back pressure", it is like designing a snake with a mouth the size of a pea and a rectum the size of a grapefruit! I have a V8 Juice can wrapped in fake carbon fiber with 1 1/2" pipe brazed to the back witha hose clamp on it, when clients ask about BIG exhaust I pull it from under the counter and offer it to them for $300

Just my ranting.

I, as well, would be very interested in knowing of a better sway bar for the SEL. I know that Bergwerks carries some at http://www.bergwerks.com/sway_bar.jsp but I have had so few requests in my shop that I have not really researched it.

Chris

PS. Has anyone seen a Benz fitted with an aluminum wing, air damn with window screen in the vents, rice rocket exhaust tips, 22" rims, HUGE autometer tach, limo tint, curb feelers, etc. I would really like a pic.

__________________
******************************
1971 Porsche 911 Targa RSR rep.
1968 BMW R60/2
1981 BMW R80GS-PD, dual plugs, 1000cc jugs, 10 gal "Gaston" tank.
1982 BMW R80GS-PD, duplicate of above.
1988 Neoplan/Mercedes 40' Bus
2002 SLK32 AMG
2013 Smart Electric

Chris,

You've gotta take it easy on the caffiene. I love what you're saying. I think you understand where I am coming from. I'm not interested in turning my MB into a kidney pounder, just creating a little more controlled handling. I love your rants, I know exactly what you mean about the slam em down, coffee can guys.
They're all about visual aesthetic (ugglly to me) and nothing about what is appropriate for the engineering of the car in terms of its component parts.

__________________
prop up the faith,
whutchens