Disabled the driving aids. Here are my impressions.

[stugray]

Originally Posted by bestwheelbase

And about EBD:

"EBD is the precursor to ABS, where brake pressure is reduced at wheels that are carrying the least amount of weight (i.e., the rear wheels during hard braking, when weight shifts forward) to prevent a skid. EBD uses the same actuator and wheel-speed sensors as ABS, but EBD only needs to detect subtle differences in wheel speed before it reduces brake pressure on a lightly loaded wheel (or wheels)."

It sounds diss7 is experiencing EBD and believes it is ABS.
The EBD would definitely use the G-force sensor to know when the rear wheels are "unloading". And pulsing at the pedal might be detectable as the system is modulating the rear brake pressure.

I never asked the OP how he knows the ABS is "activating" I tested my car last night on the ice. When the ABS kicks on there is no dash indicator, just the pulsing from the pedal. My previous Toyota had a dash indicator illuminate when ABS was activated.

[spralwers]

sometimes when I'm throwing the car around a snowy parking lot with all the aids disabled, the traction control light sometimes blinks (or maybe it blinks all the time, I'm just not paying attention). Don't honestly know how much it's actually interfering with the car though.

[Suberman]

Originally Posted by spralwers

sometimes when I'm throwing the car around a snowy parking lot with all the aids disabled, the traction control light sometimes blinks (or maybe it blinks all the time, I'm just not paying attention). Don't honestly know how much it's actually interfering with the car though.

The TC will operate if excessive drive wheel wheelspin difference is detected.

Try driving off with one side of the car on bare road and the other on a slippery surface, with TC fully off, and the TC will operate to limit wheelspin.

This combines the best features of the Torsen with the best features of purely electronic LSD systems.

The system is set up to limit wheelspin differential to a pre-set maximum. If both wheels are spinning it doesn't interfere until the difference exceeds this maximum.

[Suberman]

Pulling the ABS fuse would disable the TC and VSC to the extent the wheelspin is controlled using ABS reservoir pressure. It would not affect throttle control effects.

EBD is a "precursor" to ABS only in the sense that EBD is the part of ABS software that balances line pressures to each wheel to equalize braking effect at each wheel, stabilizing the car under braking. It is part of the ABS software and was a refinement of same. It is not a precursor historically, EBD came later, but it is a precursor operationally, it operates first before the full ABS anti lock effect is required.

EBD would help you reduce lap times whereas ABS might not.

In general, racing drivers would have ABS if the rules permitted. There are pretty rare occasions where locking brakes at one end or corner of the car can make you faster. It takes exceptional skill to achieve this. The only other drawback with ABS is it requires very different driver control during a spin. This issue is believed to cause some single vehicle accidents which are otherwise difficult to explain. Insufficiently experienced drivers may abdicate control during a spin and fail to control the brake pedal adequately. In a spin with no ABS standard procedure is to maintain locked wheels until vehicle orientation resumes a useful attitude then the vehicle is steered as brake locking is released at the correct time to put the vehicle where the driver wants it. The vehicle will slide in a straight line in the direction the initial momentum vector indicated at the commencement of the spin, you know where you're going to feel the pain, its "straight ahead". What you don't know for sure is when steering control can be regained. That difference separates the guard rail heroes from the experts.

With ABS you can't do this straight line locked wheel spin, so you must be accurately aware of the effect ABS is having on vehicle orientation and maintain steering control. With ABS functioning the vehicle does not skid in a straight line, far from it. The vehicle will continue to turn during the spin as indicated by the driver's efforts to steer whether correctly inputted or not. The number one mistake is releasing brake pressure at the wrong time or by the wrong amount during the spin while ABS is operating. The second often fatal error is failure to continue inputting correct steering directions. When ABS operates and steering is demanded by the driver the contact patch forces are divided, the car slows and turns. Without ABS the wheels are locked and no contact patch forces are available for steering until wheels are unlocked by the driver. A non ABS car spins without being steered whereas an ABS equipped spinning car must be steered throughout the event and brake pressure modulation is required to maintain correct vehicle orientation at the point the spin is ended. Failure to do this results in the ABS equipped car shooting off suddenly in the direction it faces when the wheels are no longer being braked to locking point. In road accidents this is frequently completely off the road with a fatal rollover the result. Road markings then reveal to investigators, incorrectly, that the driver appeared to steer deliberately off the road. Likely he or she just failed to understand what was required of the driver in a spinning ABS equipped car: keep your foot on the brake and steer the car continuously until full directional control is resumed or the vehicle stops.

The VSC and the stability control portion of the TC use a yaw sensor (possibly two but I doubt that, usually one in the trunk is sufficient) and a steering wheel angle sensor (which for all I know may be part of the electric power assist, on hydraulic systems it is a separate sensor somewhere on the steering column).

With ABS and VSC everyone short of expert racing drivers will be faster. If you have ABS then VSC is very handy indeed, whatever you personally may think. Ferrari's test driver has been quoted as saying that the electronic aids on the 458 Italia permit a normal Ferrari customer to lap Fiorano within a second or so of him. Think about that when you reach in to pull that fuse.

[enwave]

Sounds like a TON of great information has come out of this thread, despite some negative conversation in the beginning to middle of it. Great stuff here.


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