seahonu

Specifically, what does the ESP (traction system) do when launching hard and one rear wheel spins?

a) engine output reduced electronically until spin is eliminated
b) rear brake applied to the individual spinning wheel
c) both
d) neither, its doing something else

MB Fanatic

C. But the brakes are applied to both rear wheels.

The next version of ESP in the new 2010 E class will even account for cross camber winds, road conditions, and have other safety gizmos as part of ESP.

seahonu

Oh dang. I thought ESP would only brake the ONE wheel that is spinning. So in order to get max traction, one would really need an LSD/Quaife. Meaning so that the ESP is not triggered to brake both sides. Correct?

Diesel Benz

ESP is not the feature taking care of wheel slip, that would be ASR although that and ABS and many others are actually controlled by the same control unit.

Anyway, ASR does brake individual wheels. If necessary, it would brake both rear wheels (on a RWD car).

Brakes are in practise always applied first, then engine power is reduced to avoid wheel slip. This is because brakes can be operated faster than the engine power can be reduced.

ASR cannot reach exactly the same traction as a mechanical LSD would provide but close.

seahonu

Thanks DieselBenz. That's what I thought our ESP/ASR was doing, ie. engine power and individual braking. So getting an LSD or Quaife, wouldn't make that much of a difference. I've heard others remarking with the Quaife, its night&day on how it helps acceleration at launch and thru the corners. But don't know whether its worth the $3K for parts & labor.

I'm just curious and annoyed with the recent rains here in northern CA, how my E320-CDI is slipping/spinning alot and how much the car deaccelerates with ESP/ASR. Admittedly when I turn ESP off, its much worse with a wheel totally spinning and going nowhere. I'm thinking that the ESP/ASR is tuned more conservatively and more aggressive driving would do better with the Quaife. Sounds like yes, but not by much.

MB Fanatic

Have you checked your tires? I had the stock Michelin's on mine and well they simply SUCK. I see you have CLS wheels, but don't use OEM tires.

Try some Michelin Pilot Sport A/S Plus. Fantastic tires. I just put them on my E320 Bluetec and they are fantastic tires. They stick to the road and have amazing grip, plus 30K tread warranty.

seahonu

Yes, the tires that came with the CLS wheel were OEM, Michelinm HX MXM, which do seem terrible in rain/wet. I've been trying to wear them down, but taking some time. Obviously a new set of tires are cheaper than a Quaife.

Television

ESP works on a pendulum device mounted on the front axle.
If you were going around a bend and the back broke loose, the pendulum would move under the force of the back braking out and use the BAS to apply the brakes to the correct wheel to correct the slew of the car and put it back on track.

I try and get across to folk the dangers of fitting wheels with the incorrect ET,, under the above conditions the ESP could over or under react as the width track of the wheels has changed