R230 Rear Suspension Problem.

[sausage]

I am perfectly OK with people suggesting things, but I do not think it is helpful to state something is clearly wrong when you were talking about chassis and subframe, especially considering you are only guessing, and specifically that we do not understand the extent of the issue, and even further, that the characteristics are somewhat normal to the cars although perhaps not as severe as in Graham's case, but that last factor is something you and I cannot determine.

Perhaps I put 2 and 2 and got 3; my interpretation of your posts was that you were talking about one of the worst case scenarios and you reinforced that opinion when you said something is clearly wrong, I assumed you were still referring to the subframe and chassis - sorry. Yes, these do need to be considered, but first things first - check the tyres, get professional advice from trusted traders. Had the OP interpreted your comments like I did (my fault) then potentially this leads to Graham visiting a trader and asking them to check subframe bushes and chassis, where there are cheaper things to be checked first. I would consider "old tyres" to be wear and tear items and not necessarily 'something wrong', but yes, you are of course correct, old tyres causing poor handling is 'something wrong'. My bad.

As for suggesting I do not think forum members should make suggestions, well you are just misinterpreting my intent. My intent is to not scare monger, or suggest serious failures/worst case scenarios without having facts to hand.

 

[Graham Tricker]

Update: Over the last few days I have driven about 250 miles on all different types of roads including motorways and I can report back that the car has settled down nicely. The original problem I experienced driving the 7 miles back from the garage has lessened to the point that it is now no worse than it was originally. The Bilsten OE dampers (the black ones, not the yellow sports ones) are working very well and there is a lot less noise coming into the car. This is to be expected seeing at the original dampers were 12 years old. I was perhaps a little anxious during the initial drive of the car which prompted me to raise this issue. Now the car only appears to move about slightly at the rear when a large bump is experienced. The car is also booked in to have a full suspension check and alignment in a couple of weeks time so I will report back more fully after that.
Many thanks for all the advice and constructive comments.

 

[sausage]

Great news. Glad it has worked out OK.

 

[Graham Tricker]

Great news. Glad it has worked out OK.

I still don't think it is fully sorted, but and I have a few checks that will be done over the next month and will report back.

 

[SL63 Mark]

No rear suspension issues on my SL55, it holds the road like glue. I take it this car does not have ABC.

 

[Graham Tricker]

No rear suspension issues on my SL55, it holds the road like glue. I take it this car does not have ABC.

That is correct. It has normal springs and dampers. The problem is not damper/spring related. There is a small amount of movement somewhere that is causing instability when the suspension moves up and down over bumps in the road. My old E46 M3 did exactly the same thing and that was a disintegrated bush in the rear wishbone, masked by 2 other bushes. My SL is not as bad as that, despite the rear suspension being a lot more complicated, so the problem could be quite difficult to find.

 

[noonboots]

I had a similar problem with the rear end skipping sideways under hard acceleration. Information on the net pointed to failed rear sub frame bushes. In anticipation I bought the parts with the intention of fitting them when I did the coilover conversion. However I found absolutely nothing wrong so put it back together as it was. Since the conversion the problem has gone completely. So in my case possibly yet another ABC issue. Or maybe the answer was rear end geometry issues. If I was changing the struts on a 350 I would have bought adjustable coilovers rather than OE. I love the way my car drives now although it took a fair bit of trial and error to get right.

 

[wizzman]

My SL500 felt like it was lurching about on certain road surfaces. A very strange sensation but new rear tyres completely cured it. At a later date during a bit of rear suspension maintenance I found play in both outer bottom radius arm bushes ( which are a sort of rose joint ) This has stopped the inside edge of the tyres scrubbing as well but as has been mentioned, you can’t always detect wear / play until you have it in pieces.

 

[Graham Tricker]

UPDATE: Finally I got the handling problem sorted on my 350 SL. I took the car to Northampton Motorsport on Monday, a company I have used in the past many times and had excellent experiences with, and Monday's visit was no exception. They drove the car first and confirmed that there was definitely something not right with the handling.

Firstly, they found the front offside camber was out, so that was adjusted into spec.
Secondly, they found the "toe" on both sides at the rear was out, so this was realigned so the front and rear now meets the factory alignment specifications.

I was a little sceptical that alignment would fix the handling issue, but driving it home it was like a different car. Now there is no bump steer and less tyre noise from the rear and its much quieter inside the car. The SL must be quite critical on alignment, because with it set up correctly it drives amazingly well.
I hope this helps anyone with a similar issue.

 

[star]

Glad you got it sorted, getting the geo done before replacing anything could have saved you a lot of money.

 

[Graham Tricker]

Glad you got it sorted, getting the geo done before replacing anything could have saved you a lot of money.

Thanks, I have owned cars long enough to know that a heavy car with 12 year old dampers like the SL will not be performing at its best. I am not griping about any costs because I intended to replace the dampers anyway. Now the ride on the road, especially over rough surfaces is superior to what it was with the 12 years old parts fitted. It now glides over the rough surfaces with a lot less noise. All the geo did was fix the bump steer.