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Discussion Starter #1 (Edited)
Having spent hours adjusting my AIRmatic height levels using SDS, only to find that after a couple of days they were back to where they were before I started, ie the car with a slight lean, I came across a posting by MB World Fanatic aleksandar1099 as to why. And note, if the AIRmatic does not leak, the levels should remain the same day after day.

You cannot just use the SDS "Actuations" to lower or raise the levels as the car's computer will not store the final values. You have to use the "Initial startup mode" in SDS and save at the final step.

The MB World article explains how; https://mbworld.org/forums/w211-amg/326084-star-diagnostic-how-diy-lots-o-pics.html

The level adjustments are meant to be performed with the car on a chassis alignment system and the inclination angles, as measured by a Romess CM-09606 inclination measuring instrument, entered into SDS just prior to saving the final values.

But the article relates to a W211 and not a W220.

The article states for a W211 the following inclination angles; LF 3.5, RF 3.5, LR -1.1, RR -1.1 may be used.

Further research shows the CM-09606 measures "the vehicle level (ride height) is gauged using the position of the transverse link on the front axle and the drive shaft on the rear axle as reference points", so I guess I could take a few measurements with an angle gauge and see what I get.

However it will be easier if anyone knows what a W220 would show for typical inclination angles as measured by a Romess CM-09606 inclination measuring instrument?

TIA,
Brian
 

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Having spent hours adjusting my AIRmatic height levels using SDS, only to find that after a couple of days they were back to where they were before I started, ie the car with a slight lean, I came across a posting by MB World Fanatic aleksandar1099 as to why. And note, if the AIRmatic does not leak, the levels should remain the same day after day.

You cannot just use the SDS "Actuations" to lower or raise the levels as the car's computer will not store the final values. You have to use the "Initial startup mode" in SDS and save at the final step.

Tes MB World article explains how; https://mbworld.org/forums/w211-amg/326084-star-diagnostic-how-diy-lots-o-pics.html

The level adjustments are meant to be performed with the car on a chassis alignment system and the inclination angles, as measured by a Romess CM-09606 inclination measuring instrument, entered into SDS just prior to saving the final values.

But the article relates to a W211 and not a W220.

The article states for a W211 the following inclination angles; LF 3.5, RF 3.5, LR -1.1, RR -1.1 may be used.

Further research shows the CM-09606 measures "the vehicle level (ride height) is gauged using the position of the transverse link on the front axle and the drive shaft on the rear axle as reference points", so I guess I could take a few measurements with an angle gauge and see what I get.

However it will be easier if anyone knows what a W220 would show for typical inclination angles as measured by a Romess CM-09606 inclination measuring instrument?

TIA,
Brian
Brian,

I just went through this few months back but my memory is shot right now. I am trying to remember and from what I can, the fronts were at 0 and the rear -1.9
All level signal sensors voltage should be between 2.00 - 3.00 volts usually around 2.7 volts but I am sure you already know that :)
Also this is what helped me to get it right with the SDS ...
Lower Benz Air Suspension with MB SD Connect C4 | OBDII365.com Official Blog
 

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Brian, search my posts for this information. I posted it for someone a while ago. I'll look for it tonight when I get home and post a link to it if you haven't found it by then.
 

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Discussion Starter #4

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Hi,

Personally, if I were doing a Re Cal, I wouldn't bother trying to use someone else's figures, you'd be as well plucking a relevant figure outta thin air :wink

TBH, If you are gonna do that, you might as well just bend the Height Sensor Linkages a bit until you get it right :big laugh:

Airmatic / ABC Module Calibration is basically Synching the Suspension Angle Vs Height Sensor Voltages, so the Module will then refer to various PID's and use Tables to set the Car at the correct ride height, based upon Height Sensor Voltage, Yaw Sensors etc etc :wink

I have gone into this in depth recently............

Basically if you can get access to a Pit on Level Ground, or a 4 Post Lift that lifts level in both directions, then all you need is a "Harbour Freight" Spirit Level Angle Finder, and a Pen + Note Pad to get the correct values to enter into an SDS CAL :wink

No need for Romess or Chassis Jig :wink

Oh, and remember, with Air Suspension, set that Airmatic Single Rear Height Sensor's Adjustable link in the middle before Calibration, and then you may tweak the Rear Ride Height to get your own preferred Vehicle Stance, you will get + to - 2" on that one adjustment :devil

HTH,

Cheers Dave
 

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Discussion Starter #7
Ride Height to Suspension Angle Converters

Hi Dean and Dave, Thanks for the help.

Using Dean's suggestions I now seem to be able to store the levels after fiddling with them via SDS. I was using generic angles until I thoroughly read Dave's reply above. It is certainly impossible to measure the angles with the car at the correct height parked on a concrete floor.

Unfortunately I do not have access to a four post lift or a pit so I have reverse engineered the suspension angles in a couple of spread sheets to give me a W220 Front Suspension Ride Height to LCA Angle Converter and a W220 Rear Suspension Ride Height to Half Shaft Angle Converter.

They seem to work well and it would be good if someone could test them for me with some genuine angle data. (But I don't really expect this as it is a fair bit of work.)

Below are two snapshots of the spreadsheets. BW will not accept XL files so if anyone is interested I have uploaded them to Dropbox. https://www.dropbox.com/home/Shared%20with%20BenzWorld%20Viewers

Regards,
Brian
W220 Front Suspension Ride Height to LCA Angle Converter.jpg
W220 Rear Suspension Ride Height to Half Shaft Angle Converter.jpg
 

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I have been messing with mine as well. After I replaced a height sensor on front right that was throwing the whole car out of wack, I then proceeded to getting it calibrated to proper height.
I don't have a pit or 4 post either so I went with the 4.8 on both front and -1.9 on both rear which I'm sure is the bare minimum of spec for this 2000 s500. And sure enough this car is sitting better than it ever has since I purchased it. I've replaced 3 air struts and 1 bad height sensor then typed those specs into SDS. I might move the specs to the higher side of the spectrum which is 5.5 on both front and -1.4 on both rear and see it will accept those figures.
But overall another DIY down, learned and knowledge stored into my brain for future work.
 

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When I have played with airmatic I have just put that value in mid of range star gives in the beginning. I have just made fine tuning, is that formula calculating right for 'insane' lowrider or 'jeep' type adjustment as well? BTW Brian can you send xls via PM? I requires registration in dropbox....
 

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I'll post some pics of when it's up and when it's down based on the values I used. I personally would probably rather have it in that mid range area myself so I might readjust it. I'm going to walk out to the car and I'll lost pics with the minimum range I used then pics of mid then pics of max and let y'all tell me what you think should be the best pick. This car I will be selling so I want it as close to factory range as possible for the next customer.
 

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Okay I like the speedsheets Brian, but I don't think you are accounting for the differences that are possible i.e. a ball joint that has been undone and the retightened a couple of times will hold the end of the LCA lower, if the LCA bush is moved either inward or outward to correct alignment this will change the angle.

The way I have done this is to setup ramps with a water level so that the tops of the ramps are level then use a engineers angle/level tool to get the angles.
All you need is a length of clear hose about 4m and some water. Place the ramps where you will be using them, clip the hose to them so they are not closed off and fill with water. At this point you can see which ramp is lower and pack it up with something hard enough not to be sqaushed when the car is on them. Once you have the car on the ramps a check to make sure they are still level is advised before you start measuring and changing the hieights/angles. There you are the wheels are on level surfaces you can measure from for both the heights you want and the angles needed.

With the hose if you use a longer one you can also check the guards are level the same way. I always make sure the I use 4 ramps and level them first. I'm also lucky enough to have a good concrete area to use that only needs a couple of thin pieces of sheet metal to get them level.
 

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Discussion Starter #14 (Edited)
Thanks for all the replies and great minds think alike Dean.

I had a brain wave in the middle of the night that I could test my spread sheet ride height to angle converters by putting the car up on my ramps and stands just as Dean described. And I have now spent the whole day doing just that.

As I only have two ramps, I set the rear wheels up on them and then adjusted the front height using my trolley jack. I used the stands under the front jacking points but just clear of them as a safety measure in case the jack let go. I discovered that the car pivoted around the stands if they took the full frontal weight and thus raised the rear a further 150mm. I got the car level by using the jack under the front central jacking point with about 10mm clearance to the stands.

I was then able to get under the rear of the car and measure the half shaft angles with a digital angle gauge and compare with my measured and calculated results as per the spread sheets.

The bottom line is that the results were close but not repeatable, ie measuring the ride height and calculating the angle just wasn't accurate enough and produced a different result each time I did it. (+/-1 to 2 degrees). BTW the angle calculated by measuring the distance above ground for two defined points a known distance apart on a half shaft was within 0.5 degrees of the gauge result. At least that was reassuring to know that the maths worked.

Consequently I will remove the spread sheets and annotate my post to that effect. (Later note: I discovered I cannot edit my post #7 as it must be too old. And apparently the link didn't work anyway. Here is the Dropbox link https://www.dropbox.com/sh/ue48dsf3mb63g4h/AADC7xoNhvOU4kBfBy8XArA8a?dl=0)

As Paul says in his post the SDS will accept any angle as long as it is within the specified range and so it is easy to pick a value mid range and just store that with any height adjustments which are the important parameters.

As I understand it, the stored angle values are used to predict outcomes for the stability control programmes so a bit of leeway should be acceptable. The specs are quite broad anyway.

I will now use Pinkster's method of raising the car enough so that you can get under it when ever I redo the height settings. Since I have now used the correct SDS procedure for levelling the car, the car's computer stores the values perfectly and doesn't lean after you have driven it.

Regards,
Brian
 
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