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2008 S550 with 135K miles and it's not smooth over bumps. I feel a lot of the imperfections from the road and know that the ride should be better. The ride height is fine; back in the Fall I had to replace the level position rod in the rear of the car and had someone with the Xentry get the level right, and the car height looks fine. The shocks don't deflate after a couple days, the height stays fine. What else could cause this rough ride?
check that you’re not in sport mode on either the transmission select button (c-s) or the sport button underneath the raise lower car button.
If you’ve got both in sport mode, that might also cause a harsher than normal ride.
you’ve already confirmed that your tires are good and that your air springs aren’t deflated to where you’re riding on the bump stops.
did you take a look at the bottom of the strut units at the shock part and look for any leaking fluids?
Check tire pressure. I have mine at 29/32 PSI (front/back) and the ride is sublime (not perfect though). My relative’s W211 (with springs) rides horridly compared to the W221.
Unless you’re hauling 5 passengers with a boot full of bags, stick to 29/32.
For a while I ran them at 33/39 (road trips with 3-4 passengers and cargo, and when I was alone it felt grippy but so did every bump on the road, was harsh.
The next thing to make sure you’re doing is the C mode (assuming you’ve got a pre- facelift), S and M engage sports suspension by default.
Also like others mentioned, make sure there are no stored/current faults through OBD, as these could put the suspension in its hardest setting.
Lastly, drive it at the raised setting whenever possible.
Yeah, my 2022 GLC 53 has the Airmatic system and I've noticed it does make a slight humming noise when the suspension kicks in when taking off from a stop. Never been a major issue for me, but I've had the occasional weird creaking sound, only when the roads are super rough.
Check tire pressure. I have mine at 29/32 PSI (front/back) and the ride is sublime (not perfect though). My relative’s W211 (with springs) rides horridly compared to the W221.
Unless you’re hauling 5 passengers with a boot full of bags, stick to 29/32.
For a while I ran them at 33/39 (road trips with 3-4 passengers and cargo, and when I was alone it felt grippy but so did every bump on the road, was harsh.
The next thing to make sure you’re doing is the C mode (assuming you’ve got a pre- facelift), S and M engage sports suspension by default.
Also like others mentioned, make sure there are no stored/current faults through OBD, as these could put the suspension in its hardest setting.
Lastly, drive it at the raised setting whenever possible.
You are aware that the system adjusts ride height according to road speed? Over a set speed it drops regardless of the switch.
Also driving it raised, even at lower speed raises the centre of gravity which adds unnecessary loads to the rest of the suspension and tyres.
Sure, exercise the system and raise it for rough tracks/driveways, but not as a permanent feature.
You are aware that the system adjusts ride height according to road speed? Over a set speed it drops regardless of the switch.
Also driving it raised, even at lower speed raises the centre of gravity which adds unnecessary loads to the rest of the suspension and tyres.
Sure, exercise the system and raise it for rough tracks/driveways, but not as a permanent feature.
Yes and hence my suggestion to keep it raised. Average speed around town is in the mid 40's kph anyway, and the rough roads (sometimes with water pooling during winter) demand the higher ride.
Yes and hence my suggestion to keep it raised. Average speed around town is in the mid 40's kph anyway, and the rough roads (sometimes with water pooling during winter) demand the higher ride.
A higher ride is made possible by increasing the pressure in the air spring, which in turn would make the ride harder. The spring is essentially stiffer.
With regards to the height setting, at highway speed all modes drop down to -20 mm regardless of what your automatic comfort or sports setting is…I think it’s over 100 or 120 km/h when it drops to -20 mm of the set calibrated reference point regardless of what mode you’re in. And you essentially get the softest spring combined with whatever damping rate you have commanded with the transmission C/S and automatic comfort/sport buttons.
Sport goes to the -20 at 80 km an hour or somewhere thereabouts. It’s all in the WIS I should probably dig it up. There’s some good info.
Last edited by Max Blast; Mar 24, 2026 at 10:31 AM.
A higher ride is made possible by increasing the pressure in the air spring, which in turn would make the ride harder. The spring is essentially stiffer.
With regards to the height setting, at highway speed all modes drop down to -20 mm regardless of what your automatic comfort or sports setting is…I think it’s over 100 or 120 km/h when it drops to -20 mm of the set calibrated reference point regardless of what mode you’re in. And you essentially get the softest spring combined with whatever damping rate you have commanded with the transmission C/S and automatic comfort/sport buttons.
Sport goes to the -20 at 80 km an hour or somewhere thereabouts. It’s all in the WIS I should probably dig it up. There’s some good info.
Based on my 6k km driving the w221 elevated, I can’t say I agree with the statement that the suspension response is stiffer. If anything it’s a notch more wobbly and only on uneven surfaces.
The only time it felt stiff and uncomfortably so was when there was an airmatic error due to dirt in the front LH strut connector, cruising at 80kph on the highway felt like bouncing a baskball underneath, but that got cleared after cleaning the connector with Liqui Moly Pro-Line Elecronic Spray (which I highly recommend).
Lastly, drive it at the raised setting whenever possible.
you are not meant to use the raised ride height for normal vehicle use - to do so would be crazy - it will ride like a joke - either for air-tragic or ABS the user manual is very clear
you are not meant to use the raised ride height for normal vehicle use - to do so would be crazy - it will ride like a joke - either for air-tragic or ABS the user manual is very clear
Yes and roads here are rough, think poor speed bumps, potholes, dips and raises that one cannot avoid, On the highway where it’s better (often on one lane only as well), it goes to normal.
they really meant the "Raised" feature is to gain additional ground clearance (you may want driving on rough roads) - just like the additional clearance so snow chains don't chew the rear wheel arches
it is nothing to do with ride comfort or safe vehicle handling
You are aware that the system adjusts ride height according to road speed? Over a set speed it drops regardless of the switch.
Also driving it raised, even at lower speed raises the centre of gravity which adds unnecessary loads to the rest of the suspension and tyres.
Sure, exercise the system and raise it for rough tracks/driveways, but not as a permanent feature.
What“adds unnecessary loads to the rest of the suspension and tyre” driving in the raised position cause?
The only thing I know it makes handling a bit worse for the higher center point of gravity, but what extra loads does it cause to the suspension parts?
What“adds unnecessary loads to the rest of the suspension and tyre” driving in the raised position cause?
The only thing I know it makes handling a bit worse for the higher center point of gravity, but what extra loads does it cause to the suspension parts?
To raise the car’s level you will need to inflate the air springs at a higher pressure.
What“adds unnecessary loads to the rest of the suspension and tyre” driving in the raised position cause?
The only thing I know it makes handling a bit worse for the higher center point of gravity, but what extra loads does it cause to the suspension parts?
Raising the centre of gravity adds lateral load during cornering. That's why the handling goes to pieces. This extra load adds wear to the suspension and tyres due to the leverage from raising the centre of gravity.
It's also why the suspension drops over the threshold speed as the higher centre of gravity negatively affects stability at speed.
Raising the centre of gravity adds lateral load during cornering. That's why the handling goes to pieces. This extra load adds wear to the suspension and tyres due to the leverage from raising the centre of gravity.
It's also why the suspension drops over the threshold speed as the higher centre of gravity negatively affects stability at speed.
It's pretty basic physics😉
The lateral force comes from the speed and how tight the turn is. It does not come from riding height.
Increased in riding height makes the car roll more, but the lateral force is still the same.
More roll will put more load on the outside tires though, but in normal driving you get the same amount of left and right turns so it evens it out for the suspension parts.
The lateral force comes from the speed and how tight the turn is. It does not come from riding height.
Increased in riding height makes the car roll more, but the lateral force is still the same.
More roll will put more load on the outside tires though, but in normal driving you get the same amount of left and right turns so it evens it out for the suspension parts.
And yes, this is VERY BASIC PHYSICS.
What components do you think that extra roll applies to?
All forces on an object act around the centre of gravity. Raise that point and any centrifugal force is magnified as the moment is increased. And whilst the lateral force is not determined by height off the ground, it's effects are. Turning left or right X number of times doesn't cancel the effects, it simply equates to even wear, which is increased over driving at normal height.
Adding more air increases the pressure which is why the system fails when it isn't airtight.
You don’t know how the air spring is built.
Think about it. When you raise the car up by the about 20-25 mm you think that it is stretching the heavy duty bladder material that much with the increased pressure you claim is present?
No, the air bag is folded rubber container just the same as you see at the back of some trucks that have air springs. When car level is changed the fold of the air bag changes length and pressure in it stays the same, which is created by the weight of the car on that spring.
Think about it. When you raise the car up by the about 20-25 mm you think that it is stretching the heavy duty bladder material that much with the increased pressure you claim is present?
No, the air bag is folded rubber container just the same as you see at the back of some trucks that have air springs. When car level is changed the fold of the air bag changes length and pressure in it stays the same, which is created by the weight of the car on that spring.
your statement would be true if the airbag were allowed to expand indefinitely. But it is not; it has elasticity up to a certain point. So yes, the volume is increased by adding more moles of air into the closed system, but when the bag cannot expand any further, the additional mass of air causes the pressure in that closed system to rise.
your statement would be true if the airbag were allowed to expand indefinitely. But it is not; it has elasticity up to a certain point. So yes, the volume is increased by adding more moles of air into the closed system, but when the bag cannot expand any further, the additional mass of air causes the pressure in that closed system to rise.
PV=nRT
Does anybody in the forum have a cross section drawing of the front strut that shows how the air spring is built? I have not been able to find one.
Does anybody in the forum have a cross section drawing of the front strut that shows how the air spring is built? I have not been able to find one.
Found this picture from Arnott site. It is a bit difficult to see, but the rubber bladder is mounted between the two small yellow points wrinkled and folded above the big yellow bump stop. This is called, I think, a “rolled sleeve” design where the air bag changes length rolling over itself. This is used especially for not over stressing the air spring rubber material.
The cross section area of the spring does not change between lengths so the pressure inside the spring stays the same with all lengths (=car level). Adding air just makes the spring longer and pressure comes from the weight of the car on the spring.
Check tire pressure. I have mine at 29/32 PSI (front/back) and the ride is sublime (not perfect though). My relative’s W211 (with springs) rides horridly compared to the W221.
Unless you’re hauling 5 passengers with a boot full of bags, stick to 29/32.
For a while I ran them at 33/39 (road trips with 3-4 passengers and cargo, and when I was alone it felt grippy but so did every bump on the road, was harsh.
The next thing to make sure you’re doing is the C mode (assuming you’ve got a pre- facelift), S and M engage sports suspension by default.
Also like others mentioned, make sure there are no stored/current faults through OBD, as these could put the suspension in its hardest setting.
Lastly, drive it at the raised setting whenever possible.
I'm running 36 psi on all 4 tires, as that's what is stated on the tire. Mercedes says I should be at 33psi, I guess I'll lower it to 33 psi and see if there is much of a difference.
I'm running 36 psi on all 4 tires, as that's what is stated on the tire. Mercedes says I should be at 33psi, I guess I'll lower it to 33 psi and see if there is much of a difference.
do you have any stored or current codes?
If so, you need to clear them because that will actually put the suspension in the default hard setting. Other folks have said so and I wasn’t so sure about it but as it turns out, it is correct.: any failure of any sensor or valve will de-energize the solenoids and the adaptive damping system shock and you will have the hardest setting rebound and hardest setting damping.
(The deenergized valves referenced here are the solenoid valves on the shock, not the valves on the air Matic air spring.)
Last edited by Max Blast; Mar 26, 2026 at 10:03 PM.
do you have any stored or current codes?
If so, you need to clear them because that will actually put the suspension in the default hard setting. Other folks have said so and I wasn’t so sure about it but as it turns out, it is correct.: any failure of any sensor or valve will de-energize the solenoids and the adaptive damping system shock and you will have the hardest setting rebound and hardest setting damping.
(The deenergized valves referenced here are the solenoid valves on the shock, not the valves on the air Matic air spring.)
There are a few videos on YT regarding the repair of these valves. They're pretty much the only component that can be worked on without removing/destroying the strut.
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