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Old 12-03-2003, 08:46 PM
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dakota dakota is offline
Moof !
Join Date: Jul 2000
Location: Seattle WA USA
Posts: 469
The coupe has a fairly low final gear ratio (high numerical) (3.06:1) compared to most MBs and I suspect many other cars.

ASR (automatic slip regulation) is a form of traction control, but it is not what we generally think of as Limited Slip Differential.

I'll briefly relate what the Owner's Manual says. More info is contained in Brake System job 42-0800.

The acceleration slip control (ASR) will engage at all vehicle speeds, if one or both drive wheels begin to lose traction and spin due to excessive acceleration. While engaged, the yellow function indicator in the speedo lights up.

With the ASR engaged, the brake is applied to the spinning drive wheel until it regains sufficient traction. If both drive wheels lose traction and spin, the brake is applied to both wheels and simultaneously, engine torque is limited.

As traction on the road surface increases, the allowable engine torque also increases again and the brake is no longer applied to the drive wheels.

As I mentioned, there is a brake moment control circuit and a drive moment control circuit. The three control ranges of the ASR are:

A. Control mode with one skidding drive wheel and at wheel speeds < 40 km/h. The allowable slip threshold is higher for the Drive moment control than the Brake moment control, so the brake is applied to the slipping wheel. If it still slips too much, the Drive control comes in and retards the electronic accelerator control.

B: Control mode when both drive wheels skid or at a speed < 40km/h. Drive control has priority and retards accelerator. If wheels still skid, brake control is added.

C. Control mode when cornering at speeds between 20 km/h and 120 km/h. Depending on lateral acceleration, Drive moment control comes in sooner than for mode "B".

In addition, there is a console mounted switch, "snow chain" switch, that, when activated, increases the speed threshold of when each mode will start to engage. This "buffers" the ASR a bit and lets some slippage occur when first starting out from a stop.

There is no traditional locking differential; the asymmetrical braking independently applied to the rear wheels provides this function, sort of.

...probably more than you want to know.
1992 300CE Sportline Sophie
1990 300E Emma - in the family
1979 240D Josephine - sold, but not forgotten
2004 Pacifica AWD
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