[NefCanuck]

Okay this questions been bugging me for a while now and I was finally prodded into asking about it reading the discussion about Subaru and their AWD system as compared to the Advance Trac system offered by Ford on the Focus until the '05 model year when it was replaced with traction control.

What are the functional differences between the two systems? I mean as far as I can tell what Traction Control does is limit wheelspin by either retarding the ignition or applying the brakes at the wheels that are slipping or some combination of the two.

Example: I take a right turn at 50km/h and the TC light comes on, the engine power goes flat as the car struggles to keep me going in my intended direction (The brakes have only ever applied once, but that was taking the right turn at around 65km/h when I was in a hurry :P)

So how would the Advance Trac system handle the same situation? any differently?

NefCanuck

[euro_zx5]

Trac controls two tires (fwd slippage control) while advanced trac controls four (awd slippage control).

Trac control lowers power obviously so there is no unnecessary, uncontrollable wheel spin.

[darkpuppet]

traction control only takes measures to make sure your wheels aren't spinning..that's about al it can do. It detects wheel spin, it throttles down and/or engages the brakes (not 100% sure).

Now advance trac.. ahhh..that wonderful $1500 option not only netted you rear disc brakes, but it does the following;

It constantly monitors for wheelspin, the angle of steering wheel and the yaw of the car. So while it does perform the functionality of traction control, it will also checks to see if the car is heading in the direction the wheel is pointing. If it isn't, it throttles down the car, and modulates the brakes on the necessary corners to bring the car around.

In practice, I've noticed that there's a couple of noticeable steps the advance trac system makes.

1) it knows something isn't right, so it cuts throttle and modulates the brakes.
2) it realizes it's not going where it wants to go, and hits the brakes on opposite corners to start bringing the car around.

I personally seem to feel two or three distinctive steps as the car goes to take increasingly severe corrective actions.

ie.. in a wet parking lot, the car turns in, starts to unersteer, brakes start in, car still understeers, brakes in rear corner tightens a bit more, car starts sliding sideways... I found that if I turned in a half second before I hit a snowy corner, I could go all Colin Macrae around the corner.

[scoobasteve]

Heres a question.

Did the svt come with Advance Trac. or Traction control?

[darkpuppet]

I believe it came with traction control.

I can turn off the advance trac totally.

[NefCanuck]

Darkpuppet:

Ah, I see the difference now, so in essence what Ford is selling now (Traction Control) is a "dumb" system, ie: Wheel slip is the only reason it intervenes versus the additional things that the Advance Trac system looks for (steering wheel angle vs. direction of travel)

Also means that my system would probably do less than jack on a track to keep me going the direction I want to go ;)

NefCanuck

[darkpuppet]

yep... Advance trac is an active stability assist system, while Traction controll is just, um.. traction control.

[NefCanuck]

darkpuppet,Feb 23 2006, 03:24 PM Wrote:I believe it came with traction control.

I can turn off the advance trac totally.
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Yeah, why did Ford decide that Traction Control could never be switched off completely? Did some fool wrap their Focus around a tree after turning off the Adnace Trac system and the lawyers got involved? Makes you wonder...

NefCanuck

[scoobasteve]

I can turn off traction control... but its pretty half-assed... it is always on below 20kmh.. or something.

[darkpuppet]

scoobasteve,Feb 23 2006, 03:35 PM Wrote:I can turn off traction control... but its pretty half-assed... it is always on below 20kmh.. or something.
[right][snapback]171942[/snapback][/right]

when I turn off the advance trac, it's off period. I can do all the burnouts I want.

[NefCanuck]

scoobasteve,Feb 23 2006, 03:35 PM Wrote:I can turn off traction control... but its pretty half-assed... it is always on below 20kmh.. or something.
[right][snapback]171942[/snapback][/right]

According to the '05 owners manual, it's always on below 40km/h-25mph.

Talk about your nanny-mobile <_<

NefCanuck

[scoobasteve]

darkpuppet,Feb 23 2006, 03:39 PM Wrote:

scoobasteve,Feb 23 2006, 03:35 PM Wrote:I can turn off traction control... but its pretty half-assed... it is always on below 20kmh.. or something.
[right][snapback]171942[/snapback][/right]

when I turn off the advance trac, it's off period. I can do all the burnouts I want.
[right][snapback]171944[/snapback][/right]

Must be the wheels. :lol:

[Phantom]

Much more fun not having traction control or ABS at ALL. HA. Sure ABS would be useful sometimes, but traction control sucks. So didn't want it. Burnouts All Day All night, and no worries about pushing some button either.

[P-51]

Traction control is basically like an "electronic LSD" if you will. It monitors the wheelspeed of all 4 wheels. If one front wheel starts rotate faster than the other 3, it knows it's spinning, and will reduce spark advance to cut torque, and brakes that wheel. The brake torque on the spinning wheel will cause engine torque to transfer through the open diff to the other wheel.

If it notices both front wheels spinning faster than the rears, it reduces spark advance and brakes that wheel.

The potential benefits of this "electronic LSD" is completely nullified by the fact that it cuts engine power BEFORE braking the spinning wheel. If it weren't for that, it could actually be useful for performance.

Advance Trac actually helps stabilize the car, prevents it from excessively understeering or oversteering. I would like to try it some day, but I think I could navigate an autocross course with the throttle pinned the whole way, just steer, and let the system control the car.

It can't make the car go around a corner if the laws of physics say you're going to fast, but if you turn in early enough, the system will dump a bunch of speed for you by braking the inside wheels.

It's kind of like the scene in that latest pirate movie... with Johnie Depp...? Where they drop the anchor out the side of the ship, and it pivots around it. Feels like that.

But really, this isn't what the system is designed for. It designed to allow very aggressive lane change manoevers, without losing control. It will never oversteer, which is what put us into the wall on the 401, which is why we replaced that car with the AT ZTW.

For the history...

2003 was in fact the last year for AT. They stopped making it because it wasn't selling. I went to the plant many times, never saw a single car built with it. They had a little workbench to assemble the rear control arms with the disk brakes, and there was nobody there. They only did it every once in a while.

I believe it didn't sell because first of all they didn't advertise it well enough. The lack of understanding on an enthusiast website of all things is indicative of their utter failure to educate the buying public.

Secondly, at $1600, it was rediculously priced. The components only cost $100 on top of the price of an ABS equiped car.

They should have sold it for $500, and aggressively marketted it as a selling point of the Focus overall. At the time, it was the lowest priced car to offer the system. The next step up was a $40k BMW.

But they're too farking stupid as we all know.

The Mini does have a similar system now, but that's hardly a family car. The sales benefits of having the only affordable compact family car with this system would have been huge.

Traction control is essentially "free" once you already have ABS.

[darkpuppet]

I tried doing the autocross with the advance trac on, and I wasn't thinking far enough ahead.. it was annoying... I think it may be a bit more effective with an automatic transmission.