Problem with Air Body Control suspension
 

Dear forum-members,

I need your help with the next problem. Recently I got my new W213 with Air Body Control suspension and I'm really excited about this car. However there is a problem that completely suppresses the positive feeling, and that is the almost always present restlessness in the chassis.

On seemingly flawless flat road surfaces the suspension passes (very) small bumps disproportionately hard into the interior. As a result I can almost constanly feel irregular vibrations in the car which seriously affect the comfort. It is not a question of manhole covers or other bumps of which it is well known that the air suspension has troube with sometimes, but it is a matter of very small irregularities on the road surface which are not clearly visible. We have very good roads in the area but in about 80% of the road surface I feel vibrations. This is very uncomfortable and I find it somewhat amazing because I had the impression that I had chosen the most comfortable suspension.

Since it is not a regular vibration I do not think it has to do with imbalance in the (non runflat) tires. I have tested several configurations before my purchase but in none of the test drives I could detect this phenomenon. Moreover I notice that the suspension generally feels firmer than during the test drives.

Now there is an appointment at the dealer coming and I want to prepare myself well. Therefore I have a question for all W213 drivers with air suspension: do you recognize this problem? Or is it a technical issue with my car only.

Thanks in advance for your contributions!

In my opinion, all the new 205/213 cars exhibit this behavior on all but the smoothest pavement, it's a function of the very stiff suspension the car has in regards to bushings and mounts. What you feel is not the vertical motion that is damped by the strut, but the rearward hit when the bump first contacts the tire, transmitted into the body via the control arms. The problem is, we have 4500lb cars being asked to feel very "sporty", and using super soft bushings in that application will remove the sharpness of the steering and feel on such a heavy car.

Have you compared a steel spring car on the same roads to verify that it is just the air springs causing the change? I'd wager, assuming I am understanding you properly, that what you are feeling affects all of the cars regardless of suspension.

You mention non-runflats, what size tires are on your car, and what model? Smaller diameter wheels with taller sidewalls tend to GREATLY mitigate the very small bumps, as the tire will absorb them before even transmitting them to the wheel/suspension and onto the car. But again, for style and dynamic driving reasons, we have gone to short sidewall tires that are inherently stiffer, even in a non-runflat, and do much less damping.

Only suggestion i can make is tyre pressure?

My air suspension is excellent on good surfaces and rarely displays the hard judder on sharp edges though it occasionally occurs. I am lucky that the majority of roads i use are in excellent condition (north west france).

However despite the acoustique pack i am disappointed with the road noise on some surfaces. New smooth tarmac is stunningly good but surface dressed roads vary from audible to a horrible roar.

i have 17inch wheels 225/55/17 tyres non runflat.

Wonder if the system sensors are faulty and tge system is under too much oressure and therefore hard. Be interested in the outcome. Good luck.

I have test driven "normal" steel suspension on 17 en 18 inch and air suspension on 17 and 20 inch and none of these cars had this problem.

It's a W213 E200 and my rims are 17 inch, so a much more "forgiving" size is impossible I would say ;-)

And for the tyre pressure: I have varied between 2,2 and 3,0 bar and it hardly makes any difference.

I also have the acoustic pack and I am very satisfied with the sound level. What brand tyres do you have? Mine are Pirelli Cinturato P7 in the same size as yours.

I have the same tyres which i believe have an acoustic treatment too. On good smooth tarmac it is really good but on those where loose chippings have been laid noise levels climb drastically obviously related to the size of road chippings and their depth into the original tarmac or adherance material.

I do feel the car probably provides the best that i can access for my money and probably my expectations were unrealisticly high.

Have you reported this to your dealer and if so, how did they react?

Good to hear that. So you don not have the problem to the extent that I do. I have these vibrations most of the time (more than 80% of my driving).
Nice looking car you have by the way!

You do realize that a convertible will have some vibration in the body due to it's compromised construction? Very few convertibles are immune to this.

M

Hi I also have the sound pkg. describe the problem more. do you feel the bump inside and if so where do you feel it? feet, butt... or is it you hear it inside ???

I feel it everywhere in the car: in the steering wheel, armrests, floor etc. It would call it "vibrations". There are no sounds, I can only feel it.

Ive been having a similar issue since day one, thought it was the tires, suspension, brand of tires, made me go nuts... its been in service a few times - never fully fixed.

I do not have airbody control, and it is noticeable on better highways, I feel it in the steering wheel and the pedals, usually when coasting . can feel it right around 40mph and anything above 80+ the car feels like im driving fred flintstones car haha

The dealer did an alignment for me an also replaced the back brakes, made it a little better but I just live with it now.. Ive also driven around 4 different e300s during the times it was in service for weeks at a time. I say most of them reacted the same way... not sure if it is design flaw or it is because they think it means a more sporty ride...

I drove a 5 series a month or two ago and the steering wheel would just constantly have feedback/vibration - i hear they did this because bmw drivers complained that the prior model felt to numb...

Long story short - my e300 still feels like i am driving on a bent rim, but the roadforce balancer proves that it is not...

Could this be brake regeneration or other regeneration when you are coasting?

That is exactly what I established during my test-drives with the BMW 5 series and that is also why I ultimately choose the W213.
Sad to hear that you still have the problem and your dealer could not fix it. I still have a little bit of hope that a software-update of my air suspension could change things. But with steel springs there is not much adjustment possible. I wonder, has your dealer tried other wheels/tyres to fix the problem?

I tried to get them to throw on a fresh set of wheel/tire from another e300 to test if the problem would be resolved... they said that time wouldn't be billable back to HQ, so they wouldn't do it for me... found that pretty offensive, but what can I say.. i think im at the point where I can declare it as a lemon, due to the time it spent in service.. but not sure what car i would jump into next then..

Get rid of the RFTs.

This. I am very seriously considering selling my RFTs with 600 miles and buying new regular tires.

I've decided on the A8 due to, in large part, mercedes' stupid decision to get rid of normal tires.
That said imho it'd be silly for you to get another car as the cost for depreciation and to get into another car is well worth trying a different set of tires.

Id start with the tires first.

What's really ridiculous is the weight penalty for RFT: they each weigh upwards of 8 lbs more than normal tires (source, Tire Rack). That is ROTATIONAL mass. Big deal, that.

Very few people will defend RFTs.

The problem is automakers and their fuel economy ratings. And most customers are too stupid to push back.

I'm not defending RFT's, but I'm also not disappointed with them either. Maybe I've been rolling around on them so long now, they just seem normal and I don't find they adversely effect the ride on either the E400 or E450. I do like that they won't just blow out and I can safely drive on one completely out of air for up to 60 miles. We're virtually never far from a Mercedes dealership.

I had at least 3 or more Benz with RFTs, never caused an issue in terms of ride quality. The only bad part is if you get caught with a blown RFT on a weekend... the dealerships dont open until Monday morning and no local store carries them. I got caught on a Saturday evening a few years ago, couldnt get the car serviced till the following Monday morning!!! had to stay at a hotel lol and they only tow once up to certain miles....