[PaulT_M5]

[EDIT 28/12/17 15:54: Updated title to reflect the fact that this is a known feature]

I've just registered on a Mercedes forum, but thought I would ask here too as I know many here like to try other brands out.

I went on a 150 mile round trip to test drive a used E63 this morning. However, at the end of the test drive, I did a 3 point turn in the dealer's car park.

On full lock, moving forwards slowly, there was a "jump" through the steering wheel and a clunk noise (crabbing).

I've come home and I can find many people reporting issues with GLC43 and C43 where the front tyres crab, but none on the E class.

https://www.mercedescrabbing.org/

I wondered if anyone else had driven a 4WD W213 E class and noticed anything similar?

[PaulT_M5]

To follow up, I've had a friendly reply over on the Mercedes forum I registered on and I'm not the only one to notice it as there is an entire thread about it, though a Google search didn't find it.

The consensus is that, on the E43 and E63 and indeed any modern 4WD Mercedes, it is "normal", although still abnormal.

Now I need to decide whether this is enough to put me off and wait until the F90 is offered with £20k discounts (about April then ), or go for it... decisions!

[Tengocity]

I'd heard about this but not looked in to much. Curious as to whether the cause is understood?

[PaulT_M5]

I've just been speaking with the dealer and Mercedes stance is that it's because the sidewalls on the tyres are too shallow to deform, causing the tyres to skip across the surface.

The official line is to replace the wheels with smaller wheels and fit higher profile winter tyres to solve the problem, though I'm not sure how small you can go on the wheels on an E63 as the brake discs are bigger than my dinner plates and the smallest factory option is 19".

IMHO, this just masks the problem, it is still there.

As the issue seems to be predominantly with RHD vehicles, it seems to point to a geometry issue caused by using the RHD steering rack as one would expect all other front drive components to be the same across both LHD and RHD variants.

Unfortunately, with Mercedes' stance, my option is to either accept it "just is", or look elsewhere for a car.

[ciscopete822]

Shame , brilliant torpedo that E63.

[Chas325]

My 2004 Audi A4 Quattro does it - same reason but usually only when the tyres are getting low. Same on our 2012 A6 Quattro too. Not sure it’s just a Merc issue. And I’m talking really only on full lock

[davyk31]

The Ackermann effect it is from memory. Affects loads of 4 wheel drive stuff.

[HighlandPete]

Originally Posted by davyk31

The Ackermann effect it is from memory. Affects loads of 4 wheel drive stuff.

Yes and many cars (AWD, FWD, RWD) will do it, given the right conditions.

Seems with the Merc it brings together the worst of the contributing factors and many are feeling the problem.

Tyres have to squirm on lock in any vehicle, even perfect geometry can't completely accommodate a wide tyre. Any tyre rotating on a steering radius (lock), can't follow a perfect arc, it has width, it's trying to rotate at different speeds across the tyre, something has to give.

It's why many tyres squeal in multi-story car parks, surface is smooth and slippery, tyres move on the surface. Get on gravel you can see wheels literally jumping to release the build up of stresses.

Combine the lowest profiles, wide tyres, good drip levels from the tyre, camber changes on lock (unequal weight across the tyre), and how stiff (or soft) the suspension bushings are set up, and you have the right recipe for wheels to jump.