Russ Burns

Lets think about this. It the car is traveling 20 MPH with one wheel on ice, one on pavement, and you let up on the gas. The wheel on the pavement is going to continue to travel at 20 mph. The wheel on ice will slow down to 3 MPH (idle) (note this tire is sliding). ELD will kick in since the wheel going 20MPH is obviously spinning since the brakes are not on. And according to EDL logic, EDL brakes the wheel. Not so good.
If the wheel going 20MPH is on snow, and the edl kicks in and brakes the wheel, Now both tires are sliding. This will put the car into a spin.

Russ Burns
(pull the fuse)

Ben Broder

Don't the A4s with sport suspension also come with summer tires? And haven't they had the same ABS/EDL system we have for the past few years?

ErikR

Nope. The EDL braking is for a mere fraction of a second and only if there is a large rotational difference. It is actually quite hard to engage except at very low speeds with a lot of accelerator input.

It will not cause a spin. EDL just balances the rpm's at one end (axle). The tire on ice has its speed reduced, but it does NOT fully lock up the tire. That would certainly cause a spin.

It easy to test: Try accelerating on ice and one wheel on dry (split mu). The tire on the ice gets a few brief pulses of the brakes and the car travels perfectly straight. I can't even get it to do anything bad with the steering wheel cocked to one direction.

To get the car to spin under the lock-up theory, the back end HAS to already be moving sideways. The brake proportioning is to the front. The fronts engage abs/edl FIRST every time in my car.

Now if the car is already moving laterally and you jamb on the brakes, and you have the wrong tires on, and you overcorrect on the steering, you can get the back end to come around. No problem, I can replicate this all day long on ice. It has nothing to do with either abs or edl. Driver inputs can always cause the car to SLIDE sideways.

Jim De Arras

I suspect something like this, for sure. Perhaps complicated/triggered by ABS functioning.

Ben Broder

With limited slip diff, the force of the engine braking would be shifted to the wheel with grip, slowing it in the same way as if both wheels had traction. I'd like that alot more than the pulse(s) of EDL braking.

This raises a question. Does EDL cut out when the clutch is pressed? It certainly hope so.

Jim De Arras

And your source for this information is? (growing more tired of "Blame the driver" posts)

Russ Burns

Unless it is reading the throttle input, and realizes throttle is less than the real speed.

Russ Burns

It also could be the lifting the throttle was enough to put the car in a spin.

Russ

Russ Burns

Most people are clueless driving on ice, and then think they understand EDL?

ErikR

I thought you wanted a discussion. It sounds like the only discussion you want is one that supports your argument. Don't believe anything I say, just go out and test this yourself in a more controlled situation.