W221 steering wheel wobble/shimmer/shake

[wheels-inmotion]

Can i ask was there a time everything was ok and a point when the complaint started and if yes what happened in between?
In addition does your car have any "line deviation" sensors? Reason i ask is some sensors also have a steering shaker to warn the driver the line has indeed been deviated. If yes then the line deviation radar is out of calibration and is detecting the while line incorrectly.

 

[willg]

The car has had this vibration that manifests as a steering wheel shake since I brought it used a few months ago, I assumed it was wheel balance (as that what it initially felt like) initially. It's got 20" AMG wheels so I assumed they'd hit a pothole and been damaged, had them rebalanced several times and then another complete set of wheels put on the car by Mercedes Poole, but the car had the same vibration. I've had the car aligned three times now too so it doesn't look like an alignment issue.

It's still possible with so little rubber between the wheels and road that some pothole / impact energy was transferred to the wheel hub or suspension causing some damage there I guess? Anyway let's see what it's like with the new torque converter. I suppose it's possible with that vibrating away in the driveline other driveline support components have worn and are now out of shape.

It does have lane deviation sensors yeah, they send a vibration through the wheel (much like a mobile phone's vibration) in short bursts as you wonder across a dashed lane boundary without indicating, or if it's a solid boundary the car will brake the opposite side wheels to stop the car leaving the carriageway. It's quite distinct from the constant vibration at speed visible in the steering wheel though.

 

[willg]

The saga continues. Star phoned to say the new torque converter arrived, but makes the same noise as mine (before they installed it thankfully) so they're trying to contact Mercedes Technical to work out what's going on. I'm still not convinced it's related to the engine, torque converter or gearbox as if I measured the frequency correctly from the video I recorded, it seems to be closer to the frequency of wheel rotation (e.g hub, driveshafts or diff output).

This is a pretty informative video from Toyota about diagnosing NVH issues

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[notsofast]

Reference the video between 21:10 and 24 minutes. The run-out check is as per my previous post but the "phase matching" is a new one on me. I would think that modern wide tyres may have measurable differences across the width of the tread. Likewise, I have never found a rim dented on the outside but had several with out of true inside edges / damage. Still, the video is very interesting and shows the level of detail needed sometimes to identify the issue.

 

[wheels-inmotion]

Did the car come with 20" AMG wheels? Reason i ask is if not there can be an issue with the unsprung mass.

 

[willg]

Yep they are factory fit and on the original invoice for the car.

 

[Borys]

My s class came originally with 19" wheels. I did upgrade for 20" amg and started to feel steering wheel wobble immediately did blamed the wheels, had them balanced, straightened and problem was still there. Sold the wheels and went back to 19".....problem was there. I thougt well 20's did some more damage. It took another 6 months to find the problem. Underneath the car all seemed in perfect order. Untill suspension started to squeak. Then on a service we found front control arm is causing the noise. Repleced both and ride was perfect. Bought a set od 20's no problems what so ever. I was pulling my hair out what the steering wheel wobble can be. On my previous cls I replaced every single suspension component and again problem was with front control arms (hair line crack), we couldn't see it till it was out of the car. Sad enough on the cls it was the last bit on the car in the line to change. It is very difficult to pin point the problem. I would bet in your scenario on suspension.

 

[pembssurf]

Well mines back to main dealer tomorrow for them to re-check the play in both front bearings. I am convinced it is too much I can feel at least a mm of play on both sides in the 12-6 o clock position and can hear it clunking on the hub when I wiggle it. Book seems to say 0.01 mm so will see what happens by tomorrow evening.

 

[willg]

Borys was the hairline crack in the metal or bushing?

 

[Borys]

Bushing

 

[willg]

Thanks Borys, I've had the thrust control arm bushes changed twice now. Or are you talking about the track control arm bushes?

 

[Borys]

Sent from my iPhone using Tapatalk

 

[pembssurf]

Well £84 lighter and the news isn’t great. They rebalanced the wheels AGAIN this time they think you can see a slight side to side wobble in both near side rims. They checked the bearing play and it was spot on at 0.01mm but I can still rock it and hear metallic clunk in the 6-12pm position so I’m inclined to get a 4th opinion on the balll joints. Either way Merc wanted £480 per new rim. Haha

 

[Mr Fixit]

I have something similar on my w212, it has had discs but not fitted by MB and when I asked my local MB guys they said a disc is out of true and this happens if the hub is not cleaned properly and then when the disc is fitted and bolted down it slightly distorts the disc. It's also temp related as does not do it cold but only after a bit of braking and warm up.
In next week for discs and a hub check so let's see!

 

[willg]

I downloaded a vibration frequency logging tool for my phone so I could record the vibration and get its exact frequency. I paid for the Pro version of this https://play.google.com/store/apps/details?id=apptodate.myFrequencyFREE

And the drove the car at about 65mph with the app running on my phone on the steering column and then looked at the frequency analysis and here is the vibration I feel:

That spike with a dot on it is what I feel through the steering wheel.

 

[willg]

So I'm thinking next step is to try to find the source by attaching a vibration logger (my phone I guess ) to a control arm on each corner of the car and repeat the test, see if the vibration shows more strongly at front or back and left or right, possibly narrowing it down to one corner. Unless anyone has a better idea?

 

[notsofast]

Maybe my arithmetic might be a little off but for a wheel / hub / disc problem would the frequency not be closer to around 40Hz rather than the 13(ish) of the spike?

 

[notsofast]

Saturday night arithmetic is indeed fallible. I used diameter rather than circumference in my mental calc. With the benefit of Sunday morning coffee, 13Hz is likely to be caused after the diff. I still suspect the wheel rims until they have been measured for run out.

 

[willg]

I agree. It has to be related to be related to the rotational speed of the wheels, but I'm not sure it's the wheels themselves. Mercedes Poole swaped the wheels with a completely different set and said it made no difference, I can double check their work but the only spare set I have access to are from eBay and I haven't yet had them balanced or put decent tyres on them. I was planning to put some winter tyres on them so I may bring that plan forward (although that's a £500-£600 spend)

I've made some enquiries about vibration data loggers I could attach to various points of the car (rather than risking my phone)

The vibration is definitely stronger at the steering wheel when driving perfectly straightahead, if I turn slightly to the left or right it's less noticeable in the steering wheel.

 

[willg]

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?