trinydex

see this is why i asked you in pm if you thought a helical differential is traction control. a helical differential will sense power difference and send power to another wheel... a clutch type will do the same. but you said a differential is NOT traction control so this is why i disagree with your definitions

also with the evo's sayc, it's a yaw enabling system, not a yaw damping system. another particular point that very much contrasts with every other type of "traction control" (as you call it) out there.

http://en.wikipedia.org/wiki/Traction_control_system

i am going off the traction control definition here.

http://en.wikipedia.org/wiki/Electro...bility_control

electronic stability control is very much the same definition and if you scroll down to the mitsubishi section, you'll see that mitsubishi's TRACTION CONTROL systems are called

Active Skid and Traction Control MULTIMODE and Active Stability Control (ASC)

NOT acd or sayc. which are the two systems on the evo.

dammitjim

Stability control and traction control in cars are two different things.

SlowTeg

Trinydex,

I REALLY hate arguing over SEMANTICS. What you call system XYZ doesn't really matter to me personally. The reality is, the EVO uses an "active" traction control system and/or stability control system.

Be it called VSA, traction control, etc.. they all operate by shifting/reducing power, and are electronically controlled. Personally, I think the names of them have gotten jumbled. This thread is now thoroughly entirely off topic.. lol

trinydex

wow. did you read the definition. primary function in BOTH are to apply BRAKES or remove power to achieve their end. NEITHER of which are present in the evos up until evo 9 and i don't believe power reduction is present in evo x and i KNOW that applying brakes for stability control isn't present.

it's not about semantics, it's about FUNCTION. the function of the evo system is NOTHING akin to "traction control or stability control" in the traditional senses.

once again, if you drift in an evo, NOTHING STOPS YOU. if you slide off track, nothing is trying to bring your tail in line with your nose.

as many put it in the evo community, the only traction control you have is your right foot (and in the evo, that's enough).

trinydex

well if you want to go back to the very original point it's how preposterous this thread is. look at the poor OP. he had a LEGITIMATE reason for posing his question. he got drowned in condescension and prescriptions from FALSE DOCTORS. he probably went away from this thread back then in some amount of despair because he may have believed the only way to make his track car is to go to a stand alone and delete the entire factory ecu altogether.

i bump the thread and get met with the same, LOW AND BEHOLD, my concerns with the system were real and legitimate too...

why is this community so hostile? why is this community so set on what they "know." (or don't)

hostility was even presented--in ill inform--on one of your own track gurus.

perhaps my point was just, wtf?

socals

give it up already!

flacoloco

to the op. just get an ap1

eric1234

(edit: I see that later posts recognize and discuss static and dynamic friction. The following may not be all that helpful - I wrote it in reply to the earlier, quoted excerpt. Disregard as appropriate... ;-))

No, not quite. VSA reduces the amount of torque - to prevent the torque from overpowering the wheels. It is too much torque - overpowering the wheels - it is this overpowering that will reduce wheel grip.

This works in an identical fashion to ABS.

To start at the basics of physics: All of the grip is generated between the wheels and the ground - "grip" is really friction.

There are two kinds of friction:

1) Static friction and 2) Sliding friction. Static friction is ALWAYS greater than Sliding friction.

What does this mean: Put an object at rest on your desk and try to push it. You can apply a certain amount of force BEFORE it will begin to move. This is the Static Friction generated between the surface of your desk and the object. Lets say you can push against the object with 1lb of force before it begins to move. Static Friction can be measured by the amount of force required to get an object at rest to START moving.

Once the object begins to move, the amount of force to keep it moving at any given speed is LESS than 1lb. This is sliding friction - the amount of force required to KEEP an object moving at a given speed once it starts moving. It is ALWAYS less than static friction (I think - maybe there are some very, very rare exceptions. - Every rule has an exception or two).

What does this have to do with VSA or ABS?

Well, when a tire is rolling - it is in constant contact with the ground -> this provides the larger Static Friction. This is the MOST friction (grip) available.

When a tire is skidding (or spinning) there is relative motion between the tire and any given point of contact on the ground - in other words, it is in the sliding (reduced friction/grip) domain.

The whole point of VSA and ABS is to ensure that tires DO NOT make the transition from Static to Sliding Friction. They reduce the power to the tire to PREVENT grip from being reduced - because once grip is reduced, all sorts of (to the driver) unpredictable things may happen.

ABS does this by using speed sensors at each wheel to sense the deceleration of each wheel under braking and releasing brake pressure on a specific wheel that is at the threshold stage between Static and Sliding friction. ("Just about" to start skidding)

VSA does the same thing by using vehicle accelerometers and yaw sensors to determine those conditions when the vehicle as a whole is about to lose traction at one or more wheels (such as for the rear-end to break free). In response to such a determination, the ECU will cut power to the rear wheels, and apply one or more brakes at OTHER wheels to steady the path of the vehicle. Again - all of these (re)actions are designed to prevent the tires making the transition from Static friction to Sliding friction. In other words, all of these (re)actions are designed to enhance / optimize / prevent the grip from going down.

None of them "reduce" grip.

Best of luck,
Eric

Nickamsweet

You could always go aftermarket and program your own stability control program?? doesn't the AEM do a version of this?

eric1234

So, I've been thinking about this some more....

First: I'm not a track-trained driver, just an engineer and patent attorney who is also an auto enthusiast.

So, what I think happens here (in a nutshell) is that ABS/VSA/Traction Control are all designed to prevent the transition from static to dynamic friction. As such, they must all act at some point BEFORE the transition. Let's just say at 95%.

What that suggests is that a very skilled driver - can push further - let's say to 99%, and do better than the VSA. Such a 'magical' driver would, indeed, be hampered by the interactions of ABS/VSA.

BUT - that said, how many drivers are capable of this??? (I really don't know, to be honest - it's just a rhetorical question). Certainly, as a vehicle is operated closer and closer to the threshold, uncontrollable variations begin to come into play. What about that pebble in the road? It is going to reduce contact patch area and friction. If you were operating at 99.9%, might one pebble become the difference between success and disaster?

I would think so... The (rhetorical) question then becomes one of practicality: Should drivers (presuming they can) operate in the threshold above VSA activation? I certainly know I can't - but I imagine some of you guys that are trained and experienced can. But what happens when there are 2 pebbles right next to each other? 3? 4?

Maybe VSA is a good thing, even for experienced drivers, as it can reduce the effect of unpredictable events?

I do know that I've had VSA pop on a few times when I (with my 'standard' street skills/experience) didn't expect it to. The S2000 does seem to have a pretty tail happy tendency. Hope I've added some value or insight to the discussion...

Eric