1999 E320 4Matic traction.

[lupoelsker]

I would like to know how my 4matic decides where to transfer power when all the wheels are on different surfaces.?

Now in winter, I have had front wheels on solid concrete, and rear wheels on ice. It seems to transfer power to the rear wheels, and not the front wheels that are on the solid surface.

I do not have a ESP switch on my center console, like my 2002 4Matic has.

I thought that when you engage "winter mode" this would help with traction
under these conditions.

Another example is, I had the rear wheels on grass, and the front wheels on hard ground. It spun the rear wheels, and the front did not seem to be helping at all.

When I drive up a steep hill, where all 4 wheels are on loose gravel, it performs perfectly, with no spinning.

This may all sound stupid to you experts, but it remains a mystery to me.

I would really appreciate just a short explanation as to how the 4Matic
thinks when in the winter mode.

Please don't shoot me down in flames, as I am a Mercedes Benz super freak,
and would not drive anything else.

Anybody.??

[Figuero]

To start - Winter mode does not affect 4Matic operation. It simply will start the car off in 2nd gear rather than 1st. I've heard it has a mild affect on the shift points and it upshifts sooner than in Summer mode. That's about it.

Mercedes is very tight lipped about torque management of the 4Matic but keep in mind that our version of 4Matic uses 3 open differentals with the system applying the brakes to a "slipping" wheel to some extent. The key here is "to some extent". And the differentials are doing their best to transfer torque in a manner that creates more wheel spin, not less. This is not an off road 4wd system, and in fact it's not the best awd onroad system either. Way better than rwd, but you are seeing the limitations.
I don't have any "proof" but I believe the biggest limitation is the use of open differentials and that the brakes are applied only to the ONE wheel with the least traction (most spin). Which means that if more than one wheel has limited traction, the wheel with the second least traction becomes the weakest link in the entire system. And if both wheels with the least and second least traction are on the same axle or on the same side of the car...that's the worst of all possible conditions.
But MB isn't talking.

[lupoelsker]

That is the most sense I have heard about this matter.
I drive in the snow, ice, a lot, and most of the time it is fine, but there are times when weather conditions just become too much for the 4Matic.
Lots of yellow triangle flashing, and sometimes I just floor it, and the Mercedes has
always found something to grab onto, and gets me through it.
Thank you for taking the time to explain the system.
It may not be the best AWD system out there, but I would not change to another make
ever. Just to much fun to drive.
A good set of dedicated winter driving tires would probably stop my whining, but I drive
with the same tires year round. (Mistake I know.)

[Kajtek1]

2 separate things:
1. 4Matic is AWD system with 3 open differentials, therefore with 1 slipping wheel the car will not move with this alone, as this is a job for:
2. traction control, that clamps brake on spinning wheel.
I have been playing with 4M system a lot on ML320 and the traction does have lot to desire. While on the gravel - the 1 sec delay on traction activation had my big wheel buried down to the axle. On iced driveway the car would stop and spin the wheel for a second or 2 till traction start making its job and the other wheels would pull.
To add to the confusion - over the years MB was installing central differentials of different torque ratios. Suppose some MY had 60-40 split, meaning rear wheels got almost double torque of front ones.
It all work well for average Joe, that got surprised by bad weather on rare occasion, but for really good 4WD system you have to buy G-class with lockable differentials.

[Franasia]

Here's some more information I hope it helps to clarify it further for you:

W 210 (1995 to 2003) | mercedesclass.netmercedesclass.net

Cheers

[lupoelsker]

Traction control. Now that is where the 4Matic is lagging. If the split in torque ratio is 60-40 or more, then I guess you need the best tires on the rear. Just thinking out loud.
Studded tires help at all.??

[Franasia]

Originally Posted by lupoelsker

Traction control. Now that is where the 4Matic is lagging. If the split in torque ratio is 60-40 or more, then I guess you need the best tires on the rear. Just thinking out loud.
Studded tires help at all.??

You need to read the above link. Here's some of it:

"4MATIC was combined with the Electronic Traction System (ETS), which replaced the differential locks of conventional all-wheel-drive vehicles. ETS engages automatically if at least one wheel is spinning on a slippery surface; it increases the brake pressure until a specified speed differential is attained. This increases the drive torque at the wheels that have good roadholding, providing a maximum degree of traction."

[lupoelsker]

Thanks for that article Franasia, I posted before reading it.
Now I understand a lot more about the system, and it works just as described.
I do drive in extreme conditions, with the wrong tires, and my Mercedes has never let me down, EVER.

[Kajtek1]

Originally Posted by lupoelsker

Traction control. Now that is where the 4Matic is lagging. If the split in torque ratio is 60-40 or more, then I guess you need the best tires on the rear.

If acceleration is your only, or main goal. When I was driving in 4-seasons, I always put the best tires up front, as I valued braking and steering more.

[lupoelsker]

Originally Posted by Kajtek1

If acceleration is your only, or main goal. When I was driving in 4-seasons, I always put the best tires up front, as I valued braking and steering more.

I have always believed in the best tires up front, for the very same reasons.