g4benz

We got hit with about 15-18 inches of snow. I was reversing out of my parking spot and my wife said only my rear wheels were spinning not the front wheels. My wheels were slipping on icy snow and the yellow traction triangle was coming on. I did finally get the car out with more acceleration. My wife said she forgot to check if my front wheels started to spin when I finally pulled out. I did get out of the spot though. I had to push her Nissan out.

So my question is, is my 4MATIC working? Are all 4 wheels always supposed to spin simultaneously?

Anyone see an issue??

KEY08

Turn off your traction control and mash the pedal on snow.

g4benz

Interesting so that's how this car works in snow?

KEY08

I am simply providing an answer to your desire to see all 4 wheels spinning. Not sure what your question is.

g4benz

Got it thanks

g4benz

And I meant to say my front wheels were not rolling/moving at all. In case I wasn't clear.

davidjohnbamber

Have you considered that the rear wheels have compacted the snow so that your front tires don't have to be going at the same speed while you are in reverse?

IgorE350

What he ment was, when you shut off your traction control, you will notice the difference. Plus if its really icy or slippery you can have 6matic lol you still going to spin tires.
I check mine 4matic this way, on the turn when car starts sliding i mash the gas pedal and it straights itself out, that means ur 4matic is good. try that, but im sure ur car is fine.

g4benz

Yes that is possible.

g4benz

Sounds good I was worried for a sec lol

The G Man

4matics applies more torque to the wheels that have more traction. Your front wheels probably have no traction, like others have said, turn off the traction control.

cetialpha5

I forget the exact split, but it's more like 60 to the rears and 40 to the front. If they all spun that would mean you had no traction which probably means you were mashing the gas pedal. That's why the car still fishtails if you nail on a slippery corner. If you didn't have 4matic, you probably would have been stuck, the rear wheels would spin and the front would do nothing. There's no issue.

g4benz

It was the front wheels not moving at all that took me by surprise. Logically, I expected all 4 wheels to kick in and move/roll to get me out of the spot. I did make it out of the spot though.

Learn something new everyday - will play with traction control the next time.

The G Man

That's difference between 4WD and AWD, if it was 4WD, all the wheels will spin at the same speed.

g4benz

Makes sense!

jahquan3

The magical spinning wheels are always in effect on my RWD lol. Even on a rainy day if I don't take it easy it's like a Dukes of Hazzard re-run.

I forget how to turn off the traction control. Is it through the engineering menu?

KEY08

No, it's a button on the dash. Do you have a manual?

jahquan3

I have a manual saved on one of my computers at home. I haven't pulled it up in awhile. I really doubt I'll be turning off the traction control but just more so a FYI if someone knew it off the top.

KEY08

Yep, it is designed to be easy to turn it off when you want to. Fair warning though, it is also designed to not be "completely" turned off. To do that you do need to go into the engineering menu, especially if your car is going onto a dyno.

jahquan3

Ahh, I see - Thank You. I thought I remembered reading somewhere about it being cut off in the engineering menu.

garrettg

The 4Matic of the C, E, S, CL, CLS, and GLK models has a mechanical core that splits the torque at a ratio of 45% front and 55% rear. It works through a multi-plate lock in the center differential, which has a base locking force of 37 lb-ft (50 Nm).

Mercedes-Benz claims the system can deliver a load distribution of 30/70 in either direction, depending on ESP, 4ETS, and ASR electronic control systems and the challenges of the road surface. The electronic systems are adjusted to let the all-wheel drive do the corrections first, and then intervene to control the situation if required.

It sounds like in that situation the center plate thought there was more traction to be had in the rear wheels. These awd systems can make odd decisions during starting or stuck situations. it doesn't sound like the front tires had enough momentum to move the car even if they were getting some of the engine torque which they should have unless the passive tcs was applying the brakes. I usually turn off the basic ESP during winter conditions as it seems to easy to over throttle and confuse it.

KEY08

In heavier snows I always turn off ESP as well and find that traction and drivability improve at normal urban speeds around town.

blegthbloo

Same here... ESP is off in the snow and have had much fewer "close calls" since. The electronics are smart, but not that smart. Nothing wrong with a little oversteer in the snow

KEY08

Exactly, easy to control and ABS is always working to get you stopped properly. Turning in front of oncoming traffic in snow is always a hoot when the ESP decides to give you that long pregnant pause. LOL

Arrie

I think your center differential lock is worn out as it obviously does not have enough traction to give front wheels power to move the car when rear wheels are on slippery surface.