steering vibration when turning
Happens while the wheel is being turned.
Obviously I'll check with the dealer but wonder if anybody had anything similar? I probably knocked something out of allignment with the absurd number of potholes we have here in the NY area.
http://www.benzworld.org/forums/w212...ts-only-6.html





First of all, I don't think there is a transfer case in these cars. They are so called 4-wheel drive cars, which means there is a center differential that evens drive axle power (and speed) distribution between front and rear axles.
There also most likely are no clutch disks anywhere in the drive system. Wheel slippage, that used to be taken care of with differential lock systems, is now handled with using electronically controlled brakes.
Vibration at sharp turns most likely is caused by CV-joints. This happens if front wheel turning angle is allowed further than what CV-joint is designed for.
To understand this you need to know how CV-joints are built.
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The new double-disc clutch located on the centre differential produces a basic locking torque of around 50 Nm between the front and rear axles. In this system, a cup spring preloads the clutch pack with a permanent force. If the wheels on one of the two axles start to spin, the relative movement of the discs causes a friction torque to be transmitted from the faster-turning axle to its slower-turning counterpart.
This principle of variable torque displacement between the front and rear axles improves the traction, directional stability and road adhesion of the 4MATIC models. The traction assistance provided by the double-disc clutch is especially noticeable when the friction ratio between the tyres and the road is low, since the clutch locks the powertrain mechanically during moderate starting if the friction coefficient between the tyres and the road is less than µ = 0.3 (more or less equivalent to snow). The wheels are prevented from spinning in such a way as to avoid what is known as the “polishing effect”, which leads to a reduction in the friction coefficient. Another advantage of the double-disc clutch is the improved load-change characteristics of the 4MATIC models.
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Have been learning more about this vehicle than I ever imagined. I am experiencing a very annoying high frequency vibration in the steering wheel on my 2010 E-350 (started at around 6500 miles). More intense under load than when engine/drivetrain not loaded and not speed related. My Dealer unable to identify and even replaced all four tires even though I advised I didn't think it would help - and it didn't. My Dealer waiting for MB rep to get in town and drive the car. I believe it is a transfer case issue so am taking it to another dealer who, when I described the problem, agreed and asked if the other dealer had checked the transfer case (no they didn't). What a great car for the first 2 1/2 months! Just want to roll back the clock and get this car back to the way it stareted out. Any input on this is welcomed!!!
Well, if MB built their 4-Matic as is explained in the above I am so happy I did not buy one. By the writing they use the ages old differential locking system that is rubbing those disks at all the time. Now I know why they don't recommend staggered wheels as it is difficult to find same diameters with different widths.
Can't believe they went with stone aged all wheel drive system.
There also most likely are no clutch disks anywhere in the drive system. Wheel slippage, that used to be taken care of with differential lock systems, is now handled with using electronically controlled brakes.
Vibration at sharp turns most likely is caused by CV-joints. This happens if front wheel turning angle is allowed further than what CV-joint is designed for.
To understand this you need to know how CV-joints are built.
Last edited by j21importer; Feb 3, 2011 at 06:00 PM. Reason: fix error
For a general understanding of 212 4matic, PM email address and I will location of components sheet.
Last edited by konigstiger; Feb 4, 2011 at 05:06 PM.




WOW! Who the heck gave you this instruction?
What you do is rubbing those double disks (as someone explained they exist) against each other.
MB does not recommend to use staggered wheels as just a small wheel diameter difference between fron and rear can be problematic for the car and the point where it is problematic must be those disks (=differential lock) in the center differential, i.e. wheel diameter difference makes those disks rub each other due to the different speeds the front and rear axles turn.
Mb says it is problematic if your tires are about 10 mm different in diameter (based on not recommending staggered wheels as the sports package has without 4-matic) when overall tire diameter is about 650 mm. To make these wheels to turn one full turn difference you need to drive about 140 meters.
When you lift the car up and block rear wheels and run it in reverse with 800 rpm and then forward the same 800 rpm for one minute I cannot even think how many rounds difference you generate but every full turn equals to that about 140 m driving distance.
Anyhow, what you are doing is wearing those disks off, i.e. getting rid of the center differential lock or at least greatly lessening it.
As I understand they use cup springs. Cup springs in general are strong springs with small "stroke". Just slight wear on those disks will lessen spring force (=force between disks) a lot taking locking effect down. This for sure fixes the problem if it indeed is the two axles fighting each other thru the center differential lock but it also (at least partially) takes away the differential lock between the axles.
Differential locks should operate only when you need one and not be connected at all times.
For every 4-matic owner's sake I wish MB had used brakes for all differential locking purposes like I understand Audi does but for some reason they might not be able to.




Seems like MB has realized that they have too much lock on the center differential when they tell instructions like this to wear some of it off. Well, for most of the drivers lock is not needed and it can make car to handle better when it is not as strong. You only really need the lock during aggressive acceleration or when you are stuck anyway.
In sum though - really sounds like this is not something to worry about. Obviously its annoying when it happens (and I shouldn't) but its not going to leave me stranded or wrecked!




In sum though - really sounds like this is not something to worry about. Obviously its annoying when it happens (and I shouldn't) but its not going to leave me stranded or wrecked!
Yes, it really seems nothing that would leave you on the road. As I understand it happend when making very sharp turn on parking lots etc. This is when you generate speed difference between front and rear axles and if the disks are sticky they vibrate obviously because drive shafts and other drive components are flexible.
It just is that a car of this magnitude should not have a problem like this.


