It feels like my car understeers less when I have it set to Gravel than when I have it set to Tarmac.

Is that true, or is it all in my head?

 

Hmmm, maybe I should try it out for myself. I wouldn't have thought of trying it if you didn't say anything. I only run Gravel mode in the rain or if I'm gettin dirtay!

 

Understeer is while braking (generally speaking), and your ACD mode is not making a difference at that point.

 

Doesn't it lock the center diff. under braking? Then as you turn it opens it, and having it in gravel mode opens it later than having it in tarmac mode. Again, I'm not challenging, just clarifying.

 

I would be keen to find out if I get less understeer going into a corner fast without (or with very little) braking if I have it set in Gravel or Snow mode vs Tarmac.

There was some rumours earlier on in another forum that claimed that the ACD lifespan is severely compromised if you leave it on Gravel or Snow while driving on tarmac

Subscribing...

 

ACD Sticky:
https://www.evolutionm.net/forums/sh...d.php?t=175195

In snow driving, I found that when turning my car would push more with gravel or snow. But, it was easier to move forward in g or s.

 

You don't need to be on your brakes to feel understeer.

I'm talking about normal driving, no braking, no rain, no snow. It feels like when I'm accelerating through a turn, I get less understeer in Gravel mode than in Tarmac mode.Yes, I'm aware of that. But it doesn't explain what happens in normal driving sensation and what effect it has on under/over steer.

 

well i just been schooled after reading that i totally was wrong what the acd does.

 

I experience understeer w/o braking. It comes from a late apex or too much speed into a turn.

One thing I noticed on an auto-x course...My times varied as much as 2.5seconds slower with the car in gravel compared to tarmac. I couldnt figure out why I was not where I should be time wise and after two runs I saw the acd was set in gravel (rained earlier in the week) I switched back to tarmac and the difference was very noticable. Not so much with the understeer but the ability to get the power down coming out of corners.

 

this is correct, the modes unlock the center diff further and further into the corner from tarmac-gravel-snow. This means (all other things being equal) that you will have more understeer in gravel than tarmac and more in snow than gravel. It make sense if you think about it, the car becomes less stable as the surface gets slipperier so progressively adding understeer (with more and more center diff locking) corrects for the increasing instability

 

in theory you will understeer more in gravel and even more so in snow because the car is locking the center diff longer relative to the mode you choose. when a center diff is locked that means the front and rear axles will rotate exactly in unison which is essentially 4WD. If you have driven a 4WD truck it is super hard to turn and that is because you are fighting the center diff/transfer case, hence tremendous understeer at even 2 mph. the evo is like this in spurts when the ecu wants to. assuming you are locked in the center longer in subsequent modes you will get even more understeer. i would have to say you would get more understeer on high traction surfaces with gravel or snow than tarmac, but if you throw in some variables that limits traction significantly then the center locking diff will shine. i am a truck guy and bringing over truck theory so this info may not exactly apply to the evo.

 

That's an interesting perspective. In gravel and snow, the tendency could be for a car to oversteer (going too fast out of a corner) or to understeer (too quickly into a corner). How will the ACD know if the car is oversteering or understeeing?

IIRC, SAYC was supposed to help with that, but how does ACD come into play here?

 

Odd, what you guys are saying seems to contradict what I'm feeling. It seems like I'm able to carry more speed in Gravel. It feels like the front end digs in and pulls more, whereas in Tarmac it feels like it wants to run wide.

 

Ditto. It 'feels' like it grips better in Snow, but is it a placebo effect?

 

i think this is the first time i was like to what warrtalon said... understeer from braking means ur bout to crash... hes talking about actually cornering, with using throttle.. if you see understeer from braking your not driving right.