CLS 320 CDI Rear end wobble ?

[so called]

I changed over from my winters on 17" alloys to my summer set with 19" AMG III's last month and then headed to Germany.
As with last year, I found the ride with the AMG alloys not as good as the winters ?

However, this year there is a new twist in that when I hit a bump in the motorway/autobahn, I seem to get a bit of a lateral kick out.
I guessed that maybe I had unequal rear tyre pressures (didn't check them when I changed ) and sure enough they were 30 psi and 40 psi.
Corrected that at a German service station and ............ no difference what so ever

I also have a balance issue and have booked in for that on Thursday but cant see why that would be responsible.

Could I have a problem with my pneumatic ride suspension ? or is it just that I'm being over sensitive ?

[GlenMH]

That sounds like a damping issue. A hire car in the US used to do that to me once we had blown all the oil out of both rear dampers - don't ask how

[ZX10R NIN]

so called said:

I changed over from my winters on 17" alloys to my summer set with 19" AMG III's last month and then headed to Germany.
As with last year, I found the ride with the AMG alloys not as good as the winters ?

However, this year there is a new twist in that when I hit a bump in the motorway/autobahn, I seem to get a bit of a lateral kick out.
I guessed that maybe I had unequal rear tyre pressures (didn't check them when I changed ) and sure enough they were 30 psi and 40 psi.
Corrected that at a German service station and ............ no difference what so ever

I also have a balance issue and have booked in for that on Thursday but cant see why that would be responsible.

Could I have a problem with my pneumatic ride suspension ? or is it just that I'm being over sensitive ?

Sounds like some of your rear bushes are on there way out.

Edited by ZX10R NIN on Tuesday 16th June 23:19

[so called]

Thanks for your feedback.
My problem is that it was fine before I changed to the summers three weeks ago.
That conclusion is based on driving back from Germany, changing over to the summers and then heading to Germany again one week later and thinking "why such a big difference"?

To a degree, it was the same last year. When I went to the summers, there was a clear difference and that the wider summer tyres where not as 'nice' a ride.
I cant say I noticed the side movement last year but I cant remember.

I have experienced failed shocks and so this is in my mind here but it seems more related to the difference in the wheel/tyre sizes.

I'm going to increase the pressure in the rears to 40 and, after the balancing appointment in the morning, see what that does.
After that, there is an MB repair center near to where I am staying so will ask their opinion.

Thanks again.

[r129sl]

This may be stating the obvious, but have you checked they're bolted up tight? I had a rear wheel come off recently and the symptoms you describe are exactly what I experienced in the day or two before it fell off. Not a lesson I'll forget anytime soon.

The other thing it may be is the propensity of the wider tyres to tramline more?

[so called]

r129sl said:

This may be stating the obvious, but have you checked they're bolted up tight? I had a rear wheel come off recently and the symptoms you describe are exactly what I experienced in the day or two before it fell off. Not a lesson I'll forget anytime soon.

The other thing it may be is the propensity of the wider tyres to tramline more?

I will check that, thanks. I don't want to share that experience, especially on the Autobahn.

My TVR had a tramlining problem which is partly corrected by correct tyre width selection so yes this has crossed my mind.
I have noticed some tramlining but this is more of a hip wiggle when I go over a bump.

Thanks

[so called]

Just a short update.
I increased the rear tyre pressures to 40 and had all wheels balanced yesterday.
Interesting that the re balancing weight positioning was completely different.

End result is, feels much better, vibration gone as expected (balancing).

Will take a run down the Autobahn at the weekend for the rear end feedback.

[so called]

Update 2:
No improvement is the sideways shuffle.
Will have the bushes checked out when I get home.

[djsmith74]

I had a similar issue with my 190. The rear suspension was given a full bill of health (bushes, linkages, etc were all fine), the wheel alignment/tracking was also fine. The issue was down to partial delimitation of the rear tyres, especially around the sidewall area. Fitted new Continental tyres and it's absolutely fine now.

[so called]

djsmith74 said:

I had a similar issue with my 190. The rear suspension was given a full bill of health (bushes, linkages, etc were all fine), the wheel alignment/tracking was also fine. The issue was down to partial delimitation of the rear tyres, especially around the sidewall area. Fitted new Continental tyres and it's absolutely fine now.

My Conti's are barely a year old and have hardly done 3k miles so hopefully thats not the case.
I had a blast on the Autobahn on Sunday and find that I still have the shuffle when hitting a bump.
Also, and disappointingly, I still have some vibration and a resonance at around 130km/h.
Maybe I have a buckled alloy but I would have thought that would have been noticed with the wheel balancing last Thursday ?
I'll have them checked when I get back to the UK.

I did notice a gash in the side wall of my near side rear, Dont recall catching a kerb or anything ???? Have to get that changed