Yeah, I saw the planetary diff. Its just another kind of open diff like you said. It looks like each of the rear wheels has its own clutch. I think the active clutches are just Mitsubishi's way of making it a limited slip diff. By LSD, were you thinking of a torsen diff?

 

I have an newer model jdm gvr4 with AYC, there's no button to shut it off unless you pull fuses / force a fault. But with the Evo-X maybe the whole s-awc system needs to be shutdown since everything's so integrated.

 

this'll be a car that Mitsu will run with in Rally racing so if there'll be any similarities in the tranny used due to homologation then I would think that it could easily handle 400-500HP. Not a expert on how similar this & the rally version will be to assume for sure & not sure on the mechanical differences between a production & rallyized version of a car, but seeing how this car will be made with rally performance in mind in some form I'd say this tranny can handle at least a good 450hp at least tho some of the stock parts may need upgrading.

 

I forgot to answer this last time. The clutches in the rear diff engage those gears. The gears that you are wondering about are then used to overdrive/underdrive the right and left tires. This is how Mitsu is redirecting torque for the AYC system. However, though the front diff appears to have a similar arrangement of different gearin ratios within the diff itself, I don't see how it is regulated.

*nods* I was referring to a clasic LSD with clutch packs within the ring. I definately agree that the S-AWC system will work the front and rear diffs to lmit slip, and if the S-AWC system cannot be turned off as appears to be the case, the construction of the 'passive' side of the diff is moot.

I was just commenting on the change from a classic differential being at the core of the diff to a planetary arrangement. These 'differentials' that Mitsu has designed for the Evo X completely throw out the classic concepts. I don't know of any other car that has a completely 'active' differential.

Personally, I find this type of stuff facinating.

Thinking about the design of the S-AWC diffs, I'm not sure I'd want it off. Unless the clutches in the rear have a default postion, you'd get no power to the rear wheels. The clutchpack in the front housing appear to be used to vary how much power goes to the front. So without the S-AWC system it's theoreticaly possible that the hwole drive system will disengage and you'd go nowhere. Though I'm more apt to believe that there is a 'limp' system where the clutches will default to engaged. All this makes me belive that the S-AWC system cannot be turned off normally.


OK, all of this has made me go back to the PDFs and take another look. And I've seen some interesting things that weren't so clear before..

The front diff housing is a bit of an enigma. Supposedly the AYC system can direct torque left and right as needed for both front and rear axles. But I don't see the mechanisms that the rear has for doing that. Perhaps for the front the AYC system will use the ABS system to do that..

The other thing was how the ACD works. The clutch pack in the front housing appears to be the heart of the ACD. If that's so, then it appears that the EVO X is mostly a rear-driven setup as there is a hard connection from the transmission to the front ring to the driveshaft to the rear.

However, with the heart of the rear diff being sun/planetary arrangement with apparently freely roating planetaries, it's concieveable that the clutches in the rear act like the one in the front and can engage or disengage power to the rear axle.

But then why does the ACD display on the dash expand in both directions? I'd think that it would expand in the direction (F/R) of where the most torque was being sent. Maybe the rear diff is not as open as it looks. If that's the case then we're back at the Evo X being mostly rear-driven and the ACD display just showing how much torque is being sent to the front axle.

Wow, I really can't wait to get this car out in the snow and see how all of this works!

 

AHH! I just figured out how the AYC works and why there are two inputs into the AYC from the transmission.

The transmission has a differential-style arrangement, that's how there can be two outputs. One drives the front diff, and the other the driveshaft. The clutch pack in the front diff housing acts like a variable LSD between the front and rear outputs. So essentially the ACD reside half in the transmission and half on the opposite side of the front diff.

The ACD display on the dash is most likely how much that clutch is locked up, going from full open to full closed (50/50 split.)

I wonder why the half that's in the transmission housing wasn't shown in the ACD diagram.

 

All in all, this seems to be an impressive, if quite unconventional drivetrain, and certainly ranks among the more complex and involved systems ever designed for a production car. I appreciate your analysis Draco-Rex, keep it up :-D.

I'm still hoping that it doesn't break under strain, given the simple fact that there are now many more "points of possible failure" in the transmission given more gears and mechanicals involved. I think it's brilliant; just hope it holds up to intense use more than my early 2003 Evo transmission did.

Of course, it won't stop me from putting down my deposit.

-Adam