R230 Rear Suspension Problem.

[Graham Tricker]

My 2009 350SL is suffering from a rear suspension problemy. I have owned the car for 3 years and it has always had a tendency for the rear of the car to step sideways when driving over a bump or a rough road surface. Its worse on the nearside than the off side. The car is low mileage, as in 23,000 miles from new. Recently I had a garage change all 4 dampers for new Bilstein OEM types, and in doing this it has made this problem much worse. On a straight flat smooth road the car behaves well including round corners, but as soon as the road surface is rough or if there is a manhole or pothole the car lurches towards the side of the road where the poor surface is. It does the same on both sides but the near side is much worse than the off side. The car is in excellent condition and I am a little mystified about this problem on a car with such little use. I had a similar problem on an E46 M3 about 10 years ago. Three BMW garages could not find the problem, but a suspension specialist found the problem to be a faulty bush in one of the rear wishbones which was only apparent when the wishbone was removed. Because of this I am suspecting that it could be one of, or a few of, the rear suspension bushes, or even a subframe bush(s), but this is strange on such a little used low mileage car. Has anyone else encountered this problem and if so, what was the solution? Forgot to say my car is the sports version with 19" AMG wheels. The tyres (Continental ContiSportContact 6) are relatively new, having only done about 2000 miles. I would welcome any advice...

 

[sausage]

I was reading a similar thread this week - have a look below:

https://forums.mercedesclub.org.uk/index.php?threads/sl350-loose-rear-end.136448/

Ooops - sorry Graham, I see you have already found that post.

 

[star]

I would have kept oe suspension, changing it could and has made it worse. How old are the tyres in years? Did you have geo checked after replacing struts etc?

 

[Graham Tricker]

I would have kept oe suspension, changing it could and has made it worse. How old are the tyres in years? Did you have geo checked after replacing struts etc?

The suspension is OE. Bilstein is a supplier to MB and these are listed as OEM parts. The tyres are 2 years old and with about 2000 miles on them. I checked this morning and there is no detectable wear to the rear tyres. I have not had the alignment checked yet as this issue is more than any alignment would be able to resolve. This is some sort of failure of a part (bush) within the rear suspension. I was going to get the alignment checked/adjusted after this problem is resolved. BTW there is no wear detected on the tyres.

 

[star]

I’ll open a can of worms here, oe aftermarket is not always the same as factory fit oe. Definitely get geo checked and the tyre compound might be hardening.
my good lady’s old 350 jumped sideways on a certain bend first thing into a drive, after that no problems.

 

[Graham Tricker]

I’ll open a can of worms here, oe aftermarket is not always the same as factory fit oe. Definitely get geo checked and the tyre compound might be hardening.
my good lady’s old 350 jumped sideways on a certain bend first thing into a drive, after that no problems.

OK understood. The Bilsteins are much better made than the OE parts that came off the car. The car also rides beautifully except over rough surfaces where it pulls to the left and right depending on the surface. Note: the car has always had this problem but now it is more noticeable. It can't be how these cars are, especially the higher powered versions like the SL55, SL63 etc where going round a corner under load where the slightest undulation causes the car to move about like this would have been noted in reviews and road tests etc. There must be some play somewhere in the rear suspension which is causing this to happen.

 

[star]

Better made? But made it worse? My good ladies SL55 doesn’t jump but my S600 does tramline on certain surfaces. I doubt there’s any play at 23k miles.

 

[Graham Tricker]

Better made? But made it worse? My good ladies SL55 doesn’t jump but my S600 does tramline on certain surfaces. I doubt there’s any play at 23k miles.

I would suggest it has just highlighted the problem more as it was there originally, or at least from 16000 miles when I bought the car. Maybe it is how the car is and that alignment might make it better, but having driven high performance cars for nearly 50 years, it just doesn't feel right. I had the same thing with my E46 M3 about 10 years ago and a suspension specialist fixed it purely by chance by taking off one of the rear wishbones, where one of 3 bushes had failed. This feels like it is a similar problem but this is a multi link system, so a lot more than just one wishbone.

 

[sausage]

^^ I agree Graham and I think there is a good chance you are correct in your assessment of why this is more noticeable after you changed the dampers. With the lack of any help here (currently) it might be time to go to a MB specialist and see what they say. Ideally it would be a specialist who really knows about suspension. I also think that those sub frame bushes are worth being looked at.

Some years ago, I had a front splitter fitted on my 911. With the splitter fitted, when driving at speed sometimes the handling could be truly alarming. At one point for no reason the car jinked from the right lane to the left, and scared the heck out of me.

I had 4 different garages give opinions on the cause. Both my local Porsche main dealer and the owner of a garage who is a friend of the family and has nearly 60 years experience in the industry from Austin Chummies to F40s were adamant that I should change my tyres as they suspected tyres to be the root cause. Not an insignificant cost and one I was reluctant to commit to doubting what I was being told and suspecting it was either the fault of the custom splitter or suspension. However, no one could find any issues within the suspension set up. Eventually I did change the tyres and the improvement was massive.

Now, with the SL and what we have read so far, again I would be reluctant to look at the tyres unless they are very old/worn. You can identify the year of manufacture of your tyres from the information on the tyre wall - it is probably worth checking that they are not too old (whatever is too old??). Even though you bought them just two years ago, if they are old stock, you might have ended up with very old tyres that are exacerbating the issue. Another time after I put some new tyres on and later visited the Austin Chummy mechanic he pointed out that my tyres were 10 years old, and I had no idea this was the case having bought them from what looked like a well set up tyre place.

I would however think hard about the person that set up the new dampers and whether the set up needed to be re-checked for correct fitting, and at the same time have someone look over the rest of the suspension and the sub frame. If this was a Porsche, Centre Gravity(CG) in Atherstone would be the place people would recommend, they are reputed to be the best set up company in the UK for Porsche geo/set up, but my own experience with them when I had them do a free health check gave me a list of 11 things to do, and the reasons they needed doing. CG were almost entirely incorrect on every item. Yet the Porsche community swears by Centre Gravity and the sycophantic fan boys on 911uk.com will not allow for a bad word to be said about them and will argue to they are blue in the face about how good Centre Gravity are. Not in my experience, not at all.
So, the salient points: Is there an MB specialist near you who really knows about this stuff? Secondly, trust your own judgement and instinct as even the lauded experts can get it 100% wrong across a lot of items.

To extend that a little more. One thing Centre Gravity told me is that my car had a fast road set up and that was causing the premature wearing of the inside of my rear tyres. Yet only a couple of months earlier I had my local Porsche main dealer do a full geo set up. Centre Gravity's comments about this led me to go back to the main dealer and discuss it, it escalated and I ended up in quite a heated discussion with the dealer principle over the matter, with him claiming I was trusting a back street mechanic's word over their Porsche trained techs. He also said that CG wouldn't have the proper Porsche machine to check the geo. Well, his opinion on those points was wrong, as mentioned CG are considered UK experts and do have the proper equipment to do a correct geo set up. Eventually the principle agreed to recheck my geo and showed me the print out and it was absolutely bang on correct, 100%. This left me with egg on my face, humble and apologising and probably lost me a little credibility with the dealership. Yet, all those people on 911uk.com still swear that CG are supernaturally good at what they do. (I cannot tell you how sick I was of all the BS related to Porsche ownership after 10-11 years of it and I doubt I would ever buy another).

On another note, this unsettling handling characteristic you are asking about, could this just be a by product of the fact that the car is a big heavy convertible, scuttle shake or similar?

https://forums.mercedesclub.org.uk/index.php?threads/scutle-shake.38108/

It could be worse, there are few things worse than a Jeep Wrangler in Death Wobble:

Or maybe there is something worse: https://www.reddit.com/r/funny/comments/pn876r

 

[LostKiwi]

If you suspect a suspension problem go to a suspension specialist such as Wheels in Motion in Bucks.

My SL does similar on occasion (though not enough to bother me and it doesn't do it when 'making progress').
I've always put it down to the staggered setup and the difference in the way the fronts and rears encounter bumps due to the added rear tyre width coupled to suspension bush compliance.

 

[Graham Tricker]

Re Sausage: Thanks for the reply. I have owned a few Porsches myself including a couple of RS's (964RS & 993RS) and I know what you mean about certain companies and their fans. Back in the early 2000s it was almost obligatory to fit a K&N air filter to the 964 & 993 engine. I am not a fan of these air filters and prefer the factory paper type. I guess if you get the engine remapped to account for the extra air that the K&N flows then you might see an advantage. However, very few did this as it involved taking it to an expert, so the upshot was that the engine sounded throatier at high RPM, but one of the best characteristics of the 964/993 engine, as in good low down torque was severely lacking when the K&N was fitted, but most ignored this in favour of the extra induction noise. Having a wealth of automotive experience I know when things are right or wrong, and have found over the years that what ever modification some company offers, there might be a plus side, but there will always be a downside, probably a few, but these are never discussed.

I also had an E46 M3 which had a very similar handling problem. It felt absolutely dreadful. I took it to 3 BMW specialists, all supposedly experts in the M3, but none were able to find the problem. Then a company in Northampton (Northampton Motorsport) were offering an Eibach handling kit for the M3 at a very good price. So being suspension experts I left the car with them to fit the Eibach kit in the hope it would fix the handling issue. In taking the suspension apart they called me to say the had to take off one of the rear wishbones due to an installation problem. On taking off the wishbone they discovered that one of the 3 main rubber bushes was completely disintegrated. They replaced the bush and when the car came back it was perfect. They said that the bush was the cause of the handing issue. Thing is, that with the wishbone held in place by the 3 bushes it was not possible to feel the fault buy using jemmy bars to identify excessive play, but with the wishbone removed it was clear and obvious what the problem was. Since then I have taken several cars to NM and always had an excellent experience. It would be them I would take the SL too for a full alignment check.

Anyway, when you think the R230 chassis had many high performance models (500SL, SL55, SL63 etc) they couldn't possibly have produced cars like this if the handling trait I have experienced was how the car is from the factory! It begs the question if MB used different rubber compounds in the bushes for the more sportier models like the SL63?

 

[star]

I would have changed the tyres first, rather than shocks, far cheaper. Tyres do go hard, especially the newer compounds.
I am a merc indie with over 30years experience and I have never seen shocks or bushes wear on a merc at such low mileage, unless it’s been abused. Good luck.

 

[peterws1957]

Re Sausage: Thanks for the reply. I have owned a few Porsches myself including a couple of RS's (964RS & 993RS) and I know what you mean about certain companies and their fans. Back in the early 2000s it was almost obligatory to fit a K&N air filter to the 964 & 993 engine. I am not a fan of these air filters and prefer the factory paper type. I guess if you get the engine remapped to account for the extra air that the K&N flows then you might see an advantage. However, very few did this as it involved taking it to an expert, so the upshot was that the engine sounded throatier at high RPM, but one of the best characteristics of the 964/993 engine, as in good low down torque was severely lacking when the K&N was fitted, but most ignored this in favour of the extra induction noise. Having a wealth of automotive experience I know when things are right or wrong, and have found over the years that what ever modification some company offers, there might be a plus side, but there will always be a downside, probably a few, but these are never discussed.

I also had an E46 M3 which had a very similar handling problem. It felt absolutely dreadful. I took it to 3 BMW specialists, all supposedly experts in the M3, but none were able to find the problem. Then a company in Northampton (Northampton Motorsport) were offering an Eibach handling kit for the M3 at a very good price. So being suspension experts I left the car with them to fit the Eibach kit in the hope it would fix the handling issue. In taking the suspension apart they called me to say the had to take off one of the rear wishbones due to an installation problem. On taking off the wishbone they discovered that one of the 3 main rubber bushes was completely disintegrated. They replaced the bush and when the car came back it was perfect. They said that the bush was the cause of the handing issue. Thing is, that with the wishbone held in place by the 3 bushes it was not possible to feel the fault buy using jemmy bars to identify excessive play, but with the wishbone removed it was clear and obvious what the problem was. Since then I have taken several cars to NM and always had an excellent experience. It would be them I would take the SL too for a full alignment check.

Anyway, when you think the R230 chassis had many high performance models (500SL, SL55, SL63 etc) they couldn't possibly have produced cars like this if the handling trait I have experienced was how the car is from the factory! It begs the question if MB used different rubber compounds in the bushes for the more sportier models like the SL63?

I take it the integrity of the subframe itself has been checked and is OK? You are right about the R230 chassis - I had a go in an SL65 and the owner insisted I pressed on a bit. No skipping or jumping whatsoever even on pretty uneven roads and our piddly little 350 exhibits no such problems. Clearly summat wrong with yours which is proving hard to sort. Hope you resolve.

 

[sausage]

I take it the integrity of the subframe itself has been checked and is OK? You are right about the R230 chassis - I had a go in an SL65 and the owner insisted I pressed on a bit. No skipping or jumping whatsoever even on pretty uneven roads and our piddly little 350 exhibits no such problems. Clearly summat wrong with yours which is proving hard to sort. Hope you resolve.

I am not convinced that something is wrong. It would depend on how severe this is compared to other cars that people claim to be OK. The post I linked to above on scuttle shake certainly suggests that some element of this is to be expected.

 

[Oldspanners]

I'd go with Star on this check the rear tyres, everything from pressures hot and cold to not just when you fitted them but when they were made.
I'd a set of Pirelli which turned hard within six months and made handling "unpredictable" to say the least.

 

[Graham Tricker]

I would have changed the tyres first, rather than shocks, far cheaper. Tyres do go hard, especially the newer compounds.
I am a merc indie with over 30years experience and I have never seen shocks or bushes wear on a merc at such low mileage, unless it’s been abused. Good luck.

Thanks, I did change the tyres and they are about 2-3 years old and have done about 2000 miles. I changed the dampers as I thought the car has been sitting on them for 12 years it was time to replace them as seals degrade and so does the oil within the damper over time.

 

[peterws1957]

I am not convinced that something is wrong. It would depend on how severe this is compared to other cars that people claim to be OK. The post I linked to above on scuttle shake certainly suggests that some element of this is to be expected.

Except that the OP says the car steps sideways and lurches. Nothing like our SL350 which we've had for 5 years or the SL65 I drove.

 

[sausage]

Except that the OP says the car steps sideways and lurches. Nothing like our SL350 which we've had for 5 years or the SL65 I drove.

Which is very close to what was said to be normal in the thread I linked to. On the scale of "lurch and sideways steps" how severe do you think the characteristics of the OP's car is ? Is it at the high end of the scale, or the low end? If for "driver A" they believed the "lurch and sideways steps" to be normal behaviour they would put it at the low end of the scale. "Driver B" might judge it completely differently.

The OP, like me has had a E46 M3 (mine was a cabriolet) and it didn't do this at all, then the "lurch and sideways steps" would seem more, unusual, unnerving, more important and therefore would likely be marked as a more pronounced "lurch and sideways steps" on the scale.

Different people view the severity of symptoms in different ways, and would judge that severity differently. It is not possible from this thread to determine the severity and we KNOW that the SL DOES suffer from EXACTLY these kinds of behaviours due to the design. Therefore, I think it could be a case of the car being fine, i.e. not having a problem, and that the OP is measuring it against a car that did not ever do this kind of thing.

Not only that, one persons fast driving is not the same as another, and the kind of roads the car is used on could be in different states of repair. There are a lot of factors that could affect this, and be different in your experience to the OPs. I know a lot of people at TIPEC Porsche in the E. Mids who think they are very fast drivers, but they are absolutely nowhere near as quick as me when we go out on the track - their "fast driving" is completely different to mine. Similarly if we go out for a drive, their early morning start is 10am, mine is 5am. My "taking the car out for a spin" is 200 miles, theirs is 30 miles which to me is barely getting car warm. different people have different measures they apply.

Or to put it another way, based on the description, I believe that it is not helpful for me to go around telling the OP - "OOOO yeah you have a serious problem", when it might be perfectly normal. Not only that, would I infer to the OP his car is broke, substandard, and demonstrating serious flaws? Personally I would not appreciate people condemning my car with only such a cursory description of the fault being given. We have never seen it or experienced it's behaviour, and have no idea of the way the OP describes or perceives things. I try not to tell people they have the worst case scenario when I do not have all the information required for a diagnosis. Especially when there is information from multiple sources to suggest it could be absolutely fine.

 

[sausage]

Re Sausage: Thanks for the reply. I have owned a few Porsches myself including a couple of RS's (964RS & 993RS) and I know what you mean about certain companies and their fans. Back in the early 2000s it was almost obligatory to fit a K&N air filter to the 964 & 993 engine. I am not a fan of these air filters and prefer the factory paper type. I guess if you get the engine remapped to account for the extra air that the K&N flows then you might see an advantage. However, very few did this as it involved taking it to an expert, so the upshot was that the engine sounded throatier at high RPM, but one of the best characteristics of the 964/993 engine, as in good low down torque was severely lacking when the K&N was fitted, but most ignored this in favour of the extra induction noise. Having a wealth of automotive experience I know when things are right or wrong, and have found over the years that what ever modification some company offers, there might be a plus side, but there will always be a downside, probably a few, but these are never discussed.

I also had an E46 M3 which had a very similar handling problem. It felt absolutely dreadful. I took it to 3 BMW specialists, all supposedly experts in the M3, but none were able to find the problem. Then a company in Northampton (Northampton Motorsport) were offering an Eibach handling kit for the M3 at a very good price. So being suspension experts I left the car with them to fit the Eibach kit in the hope it would fix the handling issue. In taking the suspension apart they called me to say the had to take off one of the rear wishbones due to an installation problem. On taking off the wishbone they discovered that one of the 3 main rubber bushes was completely disintegrated. They replaced the bush and when the car came back it was perfect. They said that the bush was the cause of the handing issue. Thing is, that with the wishbone held in place by the 3 bushes it was not possible to feel the fault buy using jemmy bars to identify excessive play, but with the wishbone removed it was clear and obvious what the problem was. Since then I have taken several cars to NM and always had an excellent experience. It would be them I would take the SL too for a full alignment check.

Anyway, when you think the R230 chassis had many high performance models (500SL, SL55, SL63 etc) they couldn't possibly have produced cars like this if the handling trait I have experienced was how the car is from the factory! It begs the question if MB used different rubber compounds in the bushes for the more sportier models like the SL63?

You have had some very lovely Porsches. I drove a 993 RS 'recreation', the only difference to the factory RS was the V5 document. I hope you sold them at the "right time" Lovely cars. I also drove a few 964s and other 993s, amongst many others. I very nearly bought this in 2007, bare metal respray inside and out, re-upholstered, engine and gearbox rebuilt, new suspension and a new wiring loom and all done at a Porsche indy. It was £15,995 at that time ! I was a little wary, not knowing enough about the cars, and being unsure how much business travel my new client would inflict on me. Could I trust the old car? In the end, I bought something much newer and faster, but a lot less charming. I liked the black 911 below that much, and still lament not owning it so much that 14 years down the line, I still have one photo from the advert. Less than two years later I sold up and bought a yacht and went sailing for three years. So, the 911 in the pic would likely have been bought as a keeper, but then sold anyway and that could have been a more lamentable story. Not only the pains of saying good bye to such a pretty car, but also the change in value from 2007 to today would be a little like an unhealed wound too.

It sounds like you have some reasonable experience with the current kind of problem. As advised above, this could be the natural (albeit negative) characteristics of the car, but possibly made worse by tyres or other items wearing. Unless I was 100% sure, I would get the information from the tyre wall and ascertain the year of manufacture. Then at least you can rule in or rule out the age of the tyres for certain. Just because they were bought 2 years ago, does not mean they are 2 years old. Also the comments on the Pirelli that only lasted 6 months support the idea that old tyres could exacerbate this behaviour. It could well be symptoms are being made worse by a multitude of smaller items.

With the higher performance models, I wonder if the ABC suspension reduced the lurches and sideways steps. Most people say that the ride on the ABC cars is far superior, this could be a factor. But yes, at the same time, the engines may well have different mountings and bushes providing less lurching.
If you want to meet up and we can try each others cars (I have a 2009 SL350) and compare, then we could work something out. There is another member on here who I am due to go and see as well. Although he is local to me in Loughborough, but having three SL350s to consider might be helpful.

 

[peterws1957]

Which is very close to what was said to be normal in the thread I linked to. On the scale of "lurch and sideways steps" how severe do you think the characteristics of the OP's car is ? Is it at the high end of the scale, or the low end? If for "driver A" they believed the "lurch and sideways steps" to be normal behaviour they would put it at the low end of the scale. "Driver B" might judge it completely differently.

The OP, like me has had a E46 M3 (mine was a cabriolet) and it didn't do this at all, then the "lurch and sideways steps" would seem more, unusual, unnerving, more important and therefore would likely be marked as a more pronounced "lurch and sideways steps" on the scale.

Different people view the severity of symptoms in different ways, and would judge that severity differently. It is not possible from this thread to determine the severity and we KNOW that the SL DOES suffer from EXACTLY these kinds of behaviours due to the design. Therefore, I think it could be a case of the car being fine, i.e. not having a problem, and that the OP is measuring it against a car that did not ever do this kind of thing.

Not only that, one persons fast driving is not the same as another, and the kind of roads the car is used on could be in different states of repair. There are a lot of factors that could affect this, and be different in your experience to the OPs. I know a lot of people at TIPEC Porsche in the E. Mids who think they are very fast drivers, but they are absolutely nowhere near as quick as me when we go out on the track - their "fast driving" is completely different to mine. Similarly if we go out for a drive, their early morning start is 10am, mine is 5am. My "taking the car out for a spin" is 200 miles, theirs is 30 miles which to me is barely getting car warm. different people have different measures they apply.

Or to put it another way, based on the description, I believe that it is not helpful for me to go around telling the OP - "OOOO yeah you have a serious problem", when it might be perfectly normal. Not only that, would I infer to the OP his car is broke, substandard, and demonstrating serious flaws? Personally I would not appreciate people condemning my car with only such a cursory description of the fault being given. We have never seen it or experienced it's behaviour, and have no idea of the way the OP describes or perceives things. I try not to tell people they have the worst case scenario when I do not have all the information required for a diagnosis. Especially when there is information from multiple sources to suggest it could be absolutely fine.

No one has suggested that the OP has a "serious" problem, only that from his description there may be a problem, and presumably the reason he was concerned enough to raise the issue here. Seems a strange approach to suggest that forum members shouldn't point out potential issues when OP's raise a subject of concern though. Some highly experienced members have suggested courses of action - it's up to the OP to decide what to do.