I've searched across various forums and have not yet been able to find any thread on how the ACD affects daily driving conditions, so I thought I'd start one here in EvoM. My apologies if this has already been covered, but a site search with google didn't throw up anything like what I've been looking to get answered:

1. On normal tarmac, assuming a dry, dusty mountain road (aka twisties), how different would the car handle around :

a. tight bends --- More Under/Oversteer in Gravel
b. tight bends --- More Under/Oversteer in Snow
c. fast sweepers --- More Under/Oversteer in Gravel
d. fast sweepers --- More Under/Oversteer in Snow

2. On a wet, twisty road

a. tight bends --- More Under/Oversteer in Gravel
b. tight bends --- More Under/Oversteer in Snow
c. fast sweepers --- More Under/Oversteer in Gravel
d. fast sweepers --- More Under/Oversteer in Snow

3. Would leaving the ACD setting on anything but Tarmac when driving on Tarmac damage the ACD in any way?

It seems the above questions practically constitute some of the lesser mysteries surrounding the ACD as far as newbies are concerned, so I hope some the more knowledgeable among us would be able to share.

In the recent BMI introducing the Evo IX, Hattori used Gravel mode in his IX RS when attacking some of the corners, e.g. the Dunlop corner, in a wet 5-lap Tsukuba battle against an STI, an STI Spec-C and an Evo IX GSR. It seems that setting it to Gravel model gave him better traction on corner exit (i.e. when accelerating out of a corner)

Now, assuming that I am taking an offramp at 90 mph, and at the bottom of the ramp, on Tarmac mode, I feel the tires start to slip, would switching over to Gravel mode improve traction on corner exit in this case?

I'm not looking for technical answers, but more about real-world experiences in layman terms on the effect of the ACD on handling on high, medium and low traction surface conditions.

Thanks

this is not a good question, if you understand how acd works then you wouldn't have to ask these questions individually and you'd have an answer for all cases.

acd keeps the differential locked at an aboluste 50 50 for a certain amount of time in each mode. the more slippery the modes, the long the 50 50 is maintained after initial slip.

so... what is an absolute 50 50 split good for? slipper conditions. coincidence? i think not.

What he said..

Basically, gravel mode will lock the center differential a bit longer, thus giving more traction, but more understeer as well. And understeer can be desiriable in situations where traction is poor. It's not necessarily "faster" or "better" it's just a tool that can be used properly or improperly. If you still have troubles figuring it out, look at the FAQ about ACD.

ah, okay, that makes sense.

So to speak then, if I'm in the wet, i can get more traction and understeer in a mode that locks the diffs longer? That makes sense, thanks

that is oversimplifying too much. think of it this way

at all wheel slip (ice, no traction, gravel) the car is at it's limits on both ends. oversteer or understeer is induced by your chassis dynamics as a driver inputting biassing on the car. brakes will give you front weight and oversteer and throttle will give you rear bias and understeer. similarly breathing on and off the throttle will give you lesser extents of the aforementioned two.

throwing the absolute 50 50 on and holding it just ensures that hte computer isn't going to keep recalculating what it already knows, you're slipping and waste resources and time and power scooting things back and forth and again and again.

the more traction your surface has the faster you want this condition to go away so you can go back to moving power back and forth and using your driver inputs the normal way, without all wheels slipping.

Difference is minimal and I would bet not even perceptible to 99% of the EVO drivers out there.

Gravel/Snow mode is a fun way to get the rear end to kick out faster in dry conditions....

Terry S

^^^^ crazy