E350CDI Cabriolet steering suspension issues

Glynn350

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Hi Everyone,

I have an issue which I perceive to be getting worse since I bought the car in November, and I'd like to muse it over with you guys before I decide if/what I'm going to do about it.

A basic outline of the issue would be a very faint vibration at speed(60mph plus) accompanied by a desire to "pull" to the camber of the road (left or right).
The steering wheel tugs either way over uneven roads depending on how the wheel hits the rut/hole, with a general feeling that the front end rides over rough roads like a bag of ****, compared to the rear which feels as I expect a mercedes on 19" wheels to feel, hard but controlled. It makes you want to slow down to 20mph every time the road isn't smooth, it's also as if the dampers aren't performing to their specs due to play elsewhere. On smooth roads the dampers seem to control the car as expected.
I also get clunks on potholes that are small enough not to expect a clunk, and I get a knocking noise going from lock to lock at slow speed, mainly reversing down a sloped drive while turning onto a road.
There is also a perception of increased noise/road surface vibration in the cabin and through the wheel, though this might possibly be in my head, I'd have to drive someone else's to know for sure.

The car has just passed it's MOT and had a service, i asked for them to look at the suspension bushes on the front end during the service (non merc dealership where I bought the car from) they said everything looks fine. It had an alignment at the service which helped with the tugging a little, and it's had two previous alignments since i bought it in November last year, none of which stopped the issue, and had the front wheel bearings adjusted, and two new front tyres in March. Front wheels have been balanced twice.

My original thought was lower control arms (bushings) purely from researching the symptoms, but another search today seemed to point at either the steering rack or the rack bushings having worn.

I've had a quote of around £500 for the lower control arms, which I don't think included the labour to change them over, but I don't want to throw that money at it and not have the problem fixed.

I recognise I could take it to a different garage, a merc specialist etc, but I wanted to see if I could at least get an idea of what it might be, and the cost involved in fixing it before I decide whether to try and get it fixed or to just change the car. I love everything else about the car, but currently, unless I'm doing mainly smooth motorways, I don't like the way it feels to drive, and almost dread driving it on local roads.

Appreciate any help or advice as to what it might be, though I understand it's all speculation.
 

John Laidlaw

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Can you tell us what tyre brands you have please? Front and rear, sizes etc?
 
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Glynn350

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Goodyear eagle Asymetricals on the front, 235/35R19 , car came with some budget Davanti 255/30R19 on the rear. It started doing it with the previous Conti's it had on the front. Not sure the rear tyres would be the issue, budget or not!
 

John Laidlaw

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Mercedes cars are very very sensitive to tyres compared to other brands and you’d be amazed what incompatible tyres will do to their handling ! I was fairly certain there was a thread specifically on GY tyres and other brands not working in unison but I’m struggling to find it at the moment!
 
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Glynn350

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what tyres would you recommend? The sportcontact 6's had the same issue, that's why I changed them, along with the fact they only had about 2mm tread left.

To clarify, this isn't a "tramlining" issue, where the car tries to wander, following grooves in the road. I know how that feels, new tyres can sort that.
It pulls towards the camber of the road on a perfectly smooth road, both left and right depending on the camber (some motorways bank down towards the central reservation), though I read mercs do this, so this isn't the main issue for me.

The main issue is a feeling through the steering wheel, that if a wheel hits say a half-inch deep rut that runs across the width of the road, but not perpendicular to the road (diagonal, say), that the rut starts to sharply turn the wheel in a direction that would make it perpendicular to the rut, if that makes sense.o_O The steering wheel shimmys an inch one way quickly then back again, instead of the wheel just riding over the rut with only an up-down movement through the suspension, and not a left-right movement. It's often accompanied by a clunk of metal on metal. Feels like it's more driver side too, as in that side of the car seems to react worse to pot-holes.
 

John Laidlaw

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Yes I follow you- it did sound like tramlining or nibbling when I first read your initial post. The scrabbling or crabbing you also mentioned in the first post made me think tyres, especially wide low profiles with relatively hard wall.
Have ever had steering geometry checked ? It’s possible a combination of some adjustments there and a slightly softer sidewall tyre such as the Uniroyal rain sports or something similar if they’re not available in your tyre size would solve the issues. Interested to hear any other views out there?
 
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Glynn350

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Yeah, it's had a full hunter alignment at three different places, it still had the issue each time, but recently it has become more audible, and the ride is noticeably worse over the same local roads, crashing over the bumps more i feel.
 

bembo449

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this reminds me of an old Z3 bmw I once had , it had a set of mv2's on from a much newer bmw , it drove pretty much exactly like your describing , all over the shop on all but the smoothest of roads , so im inclined to ask if the 19's you have fitted are factory and the right offset 19's for your specific car ??
 

malcolm E53 AMG

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If the wheels are staggered figment (width) ie, 8.5in front and 9.5in rears check that a wider rear wheel hasn’t been used at the front and fitted with the narrower tyre, this does happen and will give the symptoms you describe of unsettled road holding and catching the suspension leg on lock. Difficult to spot even for a tyre fitter
 
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Gkinghorn

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My E350 Cab (2011) has a slight , very slight , pull to the left. Otherwise driving is fine. I had it Hunter aligned but there wasn’t much in it. I was told you can buy some after market camber bolts which will improve the alignment ... roughly £200 including fitting.

You may find that will help ....


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Glynn350

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If the wheels are staggered figment (width) ie, 8.5in front and 9.5in rears check that a wider rear wheel hasn’t been used at the front and fitted with the narrower tyre, this does happen and will give the symptoms you describe of unsettled road holding and catching the suspension leg on lock. Difficult to spot even for a tyre fitter
Good shout, I shall check that. I had a bit of work done once on a previous car that had staggered wheels. It needed a new rear alloy and tyre, and when I went to pick it up from the garage it looked like it had a much wider tyre on one rear wheel to the other. I pointed this out, and the guy said, yeah I noticed that, but the tyre is the correct size, it must just be a slightly different model of potenza. I took my tie off and took a rough measurement of the rear alloy, and they had indeed bought a new front wheel alloy and fitted it to the rear!
 
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Glynn350

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this reminds me of an old Z3 bmw I once had , it had a set of mv2's on from a much newer bmw , it drove pretty much exactly like your describing , all over the shop on all but the smoothest of roads , so im inclined to ask if the 19's you have fitted are factory and the right offset 19's for your specific car ??

http://www.alloywheelsdirect.net/me...le_a207_alloys/19_amg_7_twin_spoke_wheel_1742

Those are the wheels. I'm not sure if my particular car came with them from the factory, but I've seen many other e class cabs and coupes with the same wheels fitted, so I think they were a factory option.
 
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Glynn350

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Thanks for all the replies. I'm certainly going to check the alloy sizes on the front wheels, but overall I'm not sure wheels or tyres are the problem, though they would certainly make it worse. After having a couple of powerful FWD cars with wide tyres on the front, I know what the wandering of a car feels like when it's just wide tyres/wheels on a car with sound suspension and steering components, both wheels feel connected to each other, but follow grooves in the road.

This wandering/poor ride feels like a slight disconnect (play) between the two front wheels or in the rack, as in the car can't maintain the correct alignment of the wheels as they hit bumps/ruts etc.

I'm tempted to start replacing stuff, ECP and GSF have some good discounts on at the moment, which would put lower control arms and track rod ends at about £300. If the car had the 19's on from factory, thats 80,000 miles of bushings getting battered.

Before I do, I'm going to jack it up and get a pry bar in there and see if i can find any play and hopefully narrow it down to one component.
 

John Laidlaw

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I’m sure you’re right- just as a matter of interest what tread is left on your tyres now?
 
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Glynn350

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Fronts have between 5.5 and 6mm, rears have a min of 3mm.

The wheels are 8.5J all round, even though the tyre sizes are staggered, which is correct apparently!
 

John Laidlaw

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http://forums.mercedesclub.org.uk/index.php?threads/goodyear-eagle-assymetrics.150175/page-5

I think this is the thread you are referring to John. After reading it, I'm wondering if I should just throw £350 of rear Goodyears at it and hope that solves it, and if it doesn't, at least I've got some good tyres on the back.
That’s the one- well found! Apologies I’ve been preoccupied hence the slow replies.
And yes, I’d be tempted to do just that- all you lose is a couple of Davanti tyres, and hopefully gain the handling you deserve in such a car...
You’ll realise now why I was asking what tread depth you had left as this was going to be my suggestion. At 3mm you’re not losing much remaining life. I change mine at 3mm by the way anyway, the tyres do not work well below that and in general are extremely noisy!
 
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Glynn350

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Update! The car now has Goodyear eagles all round, and is much improved. The general ride on smooth to moderately broken road is miles better, and on smooth road there is much less road noise, plus much more traction at the rear! Brilliant tyres.

BUT, there is still a clunk over potholes on the drivers side, the passenger side doesn't do it over the same size holes. I do my best to avoid as I'm sure most do, but some are unavoidable.

Even so, I'm much happier with the ride in general, and am going to leave it for now as there is nothing visibly wrong that I can see, and it's passed it's MOT, so doesn't feel unsafe. I'm sure as the issue wears further, it will become visible or show noticeable play that will make it easier to diagnose. Thanks for the help!
 

John Laidlaw

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Update! The car now has Goodyear eagles all round, and is much improved. The general ride on smooth to moderately broken road is miles better, and on smooth road there is much less road noise, plus much more traction at the rear! Brilliant tyres.

BUT, there is still a clunk over potholes on the drivers side, the passenger side doesn't do it over the same size holes. I do my best to avoid as I'm sure most do, but some are unavoidable.

Even so, I'm much happier with the ride in general, and am going to leave it for now as there is nothing visibly wrong that I can see, and it's passed it's MOT, so doesn't feel unsafe. I'm sure as the issue wears further, it will become visible or show noticeable play that will make it easier to diagnose. Thanks for the help!
Excellent news. Keep an eye ( or ear) on the clunking which might be a drop link or something similar but nothing desperate at this stage it seems
 
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