W221 steering wheel wobble/shimmer/shake

[pembssurf]

Exactly the same on my C-Class with the play at 6 and 12 and Merc are still saying everything checks out. I have 0.01 mm play both sides.

I did some poking around the front suspension over the weekend. I'm not a professional mechanic as you've probably gathered, so I'm learning as I go.

I first checked for runout by jacking up the car and placing the tip of a breaker bar as close to the inside, outside and tread of the tyre whilst rotating it and watching for a gap to open or for the breaker bar to be snagged- the wheels looked true laterally, there was a small flat spot radially but I hadn't driven the car beforehand so that may just be where it had been sitting on the drive. To be sure I put one of the spare 18" wheels I had on the car and test drove it, noting no improvement.

However, I've noticed some play in both front wheels when rocking at the 12 & 6 o' positions, there is no movement at 9 and 3 so I thought ball joints, but I cannot see any movement of the ball joints when my partner rocks the wheels whilst I observe the hub, I also tried to get a pry bar involve but they seemed solid. So next I did some research and read that if you apply the brakes the pads grip the disc and provide a solid structural path between the wheel and suspension, so I asked her to apply the brakes on and off whilst I rocked the wheel and sure enough when they were applied the play stopped.

Here are some videos showing the play I'm talking about:

This is my W221 S-class front offside wheel - hear that clicking noise and see the movement of the wheel?
https://photos.app.goo.gl/bNRHhQsEVgCjybkd8

This is the front nearside wheel (skip to about 36 seconds where I move the camera closer to the wheel, also I was trying the 18" wheels at the time, hence the different alloy design)
https://photos.app.goo.gl/K6KiskzQhx34VLyo8

To try to ascertain what is considered normal I did the same test on the front of my W211 E-class estate which doesn't have any steering wheel shimmy/vibration:
https://photos.app.goo.gl/xLijJUpY7tNuQ1hn6

And the rear of the S-class too, again no movement/clicking:
https://photos.app.goo.gl/fo4AKoGCyJgsAUbx5

I'm leaning toward both front wheel bearings been worn or damaged, the reason I don't think it's an adjustment issues is I've adjusted it and checked for axial play using a dial gauge indicator and there's no movement (0.00mm).

What do you all think?

xa fly

 

[markjay]

Well if you have a spare set of wheels and tyres, and you tried those and the issue persists, then yes this rules out the wheels and tyres...

In addition to the wheel bearings, consider also the wheel hub as a possible culprit (mating surface not straight).

 

[willg]

I've ordered two new hubs from Mercedes (£220 inc. VAT each), they come as a full assembly including bearings and grease so it should be a straightforward job to replace them. Hopefully the spindles and knuckles are okay, if not they are £330 per side and a lot more work. I'll find out when the old ones come off.

They should arrive later this week, then I'll get them swapped over and report back.

 

[willg]

Swapped them over this evening, and it's made no difference as far as I can tell on my short test drive in the dark.

 

[willg]

Here are the stubs from the steering knuckes on either side. They seemed okay to me.

Here is the new hub being installed

Adjusted

The bearing grease being measured out

And post-installation vibration measurement at just under 60mph:

 

[willg]

So what have I learned so far:

• The vibration is strongly correlated with the speed of the vehicle (not the engine RPM) and comes on around 40-50mph, is worse in the 55-75mph range and starts to attentuate around 80mph
  
• The frequency of the vibration corresponds to that of the rotation of the wheels

My subjective observations:

• It's low amplitutde but annoying/tiring
• It's more noticeable when driving straight ahead, turning to the left or right slightly reduces the sensation felt throught the steering wheel
• Road camber may have an effect - I need to test this further.

Measures attempted to resolve:

• Wheel balance (at four different places)
• Wheel alignment (three times)
• new brake rotors (both sides)
• new thrust control arm bushes (both sides twice, first with same part no, second with 4matic part no.)
• new front wheel hub+bearing assembly (both sides)
• Mercedes Poole tried different wheels on the car and said it made no difference, I tried a set of ebay wheels which admittedly haven't been balanced/had new tyres

There are broadly three groups of theories that remain:

1. The rotational mass of the wheel assembly is unbalanced - whatever combination of wheels/rotators/tires/hubs that have been tried to date have been unbalanced too.
   
2. The assembly holding the wheels (suspension, tie rods etc.) has some play that allows the rotational mass of the wheel assembly to move/resonate at the speeds indicated
3. The assembly holding the wheels deflects sufficiently at the speed indicated such that one or more wheels no longer tracking exactly with the vehicle's direction

Are there any other theories or experience people can offer?

 

[notsofast]

Wow - I genuinely admire your attention to detail - You really are knocking out the possibilities.
I have no further theory as to any additional out of balance sources but have you run the dial test indicator on the inside edge of the mounted wheel rim(s)?

 

[willg]

To update everyone, as you can see in the last graph I posted, the amplitude of the vibration reduced following the wheel bearings change, I followed that up with a road force balance (at apparently the only place in Dorset that has the equipment - I thought it would be standard at a main dealer), and just the other day switched to 18" wheels and winter tyres. The overall cumulative effect is such that the vibration is largely gone. The final piece of the puzzle may have appeared just the other day after the MOT picked up play in both front lower track control arm ball joints (the ones the suspension struts attach to), the ball joint is integral in this design so both arms have to be replaced, which is scheduled for next week. I will update again with any changes after, and I have yet to decide whether to revert to the original bushings on the thrust control arms (diagonal ones) as I'm still running the 4matic bushes.

 

[willg]

The arms (variously called camber control arms/track control arms/the ones to which the suspension strut attaches) were changed on both sides and it whilst it has improved the low-speed feel of the car (it feels more 'solid' subjectively) it has not eliminated the last of the steering wheel vibrations.

Having done a long motorway round-trip recently I have some other observations:

• It's more noticable on smooth road surfaces, it either doesn't occur or is difficult to perceive on rougher ones.
  
• It's more noticeable when driving in a straight line
• Most noticeable between 50-75mph, above that it's less noticeable
  
• The frequency still matches that of the wheel rotation (I'm now running winter wheels + tyres, which are a completley different to my summer set, elimating the wheels themselves)
• It seems to occur more when the car's weight is on the left (passenger in the UK) side
  
  • When the road camber is to the left (when the camber is on the right it's less noticeable or eliminated)
    
  • When turning right (weight transfers to left) the car feels less stable than when cornering left (weight transfer to right)

I'm not going to do anything immediately, but if anyone has any ideas based on the above clues then let me know.

I am slightly disallusioned with the support available for Mercedes outside of warranty, both main dealer and independents have so far failed to find and fix the cause. Do mercedes have an advanced diagnostics centre in Germany I can take it to?

 

[MikeInWimbledon]

Wow, what a saga !

It's all a bit late, but for those who follow, my recommendation would have been to escalate it to a large tyre / balancing /tracking specialist like Micheldever tyres. They have all kinds of specialist kit to track this kind of fault down, as well as people who spend their lives working on these issues.

With all due respect to your Mercedes dealer, this kind of extended investigation is beyond them. I'm not suggesting that they're knuckle draggers, but it's a specialist area.

At first glance I would have thought that enthusiastic driving on those 20 inch wheels is the most likely trigger. "Rubber band" profile tyres look cute when parked in Knightsbridge, but the wheel, hub and suspension get MUCH more stress than the 18 or even 17 inch wheel delivers.

There's a reason why Formula 1 uses just 15 inches on the front and 18 on the back....

.

 

[willg]

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This seems to describe similar symptoms on a flat smooth road, 70mph odd. The E46 has a different suspension setup to the W221 but interesting nonetheless.

 

[willg]

So I'm adding to my list of possible causes

• Excessive positive caster
  
• AirMatic strut height differences (apparently these can be adjusted in Star)

Steer Axle Wheel Shimmy - Common Steering Problems - Hydrosteer

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[blademansw]

I had a similar issue to this on my old E39 5 series (the E39's are famed for their shimmy).

After lots and lots of expensive tryagnostics.. and completely unrelated I had decided to send the calipers off to be refurbished as the pedal felt a bit spongy. It transpired that one of the calipers must have been slightly seized as the problem went away. So it must have been just enough to cause the issue, but not enough to drag the pads and wear them prematurely.

I do feel your pain though, it took me 5 fricking years to sort!

 

[dannyfiveforty]

Did you ever get to the bottom of this, is it felt just at the wheel, or through the car also?

 

[willg]

@dannyfiveforty Nope I haven't found the root cause still. I'm doing a lot less motorway miles so it's fallen down my priority list. It's still there though exactly as I described on my 27th Dec 2018 post.

I'm reluctant to throw more parts at it, I'd like to hook up a bunch of sensors to the car to try to narrow it down more first, and maybe borrow another w221 of similar model year to compare the readings against.

 

[Sammerc350]

@willg Great post, it has been interesting following your journey as you work to get to the bottom of your wheel issue. Whilst it has been an interesting post to follow, I’m sorry you have had such problems, I hope you do get to the bottom of the issue as there is nothing worse than having a niggle that you can’t fix.

 

[dannyfiveforty]

Ok, I too am having this problem. Mines a 2011 bluetec also. Today I had the car hunter aligned and road force balanced but problem is still there. Looking at the image I have attached I have replaced the bottom left and right arms shown, again no difference. Which arms have you changed? I’m wondering about buying a complete set with all the arms..

 

[willg]

Hi Danny,

I had the bushes on the arms in the bottom left and right of your picture replaced with the stiffer bushes from the 4matic cars. I also had the left and right arms in the top of your picture replaced entirely as there was some balljoint play. I've not touched the tie rods (middle of your picture) or upper control arm (centre of your picture) on mine, but they have been inspected a few times.

Could you check something for me - if you jack the car up and spin the front wheels by hand and let go, do both front wheels rotate completely freely the same number of turns or does one side rotate more/less than the other before stopping? i.e. is there any drag, no matter how slight, from either of the front brakes?

 

[dannyfiveforty]

I will when I get next chance to, from memory though when I have checked for play in bearings there is drag on both wheels, I am assuming you are thinking the shimmy could be caused by pads running the face of the disc?

 

[willg]

Yes, that's what I'm trying to eliminate as a possible cause. I also wonder if it's more prone with the larger AMG calipers that come with the AMG sports package cars.