I've been curious about this. For my model Evo 6, there is from what I understand a center diff in the gearbox and then a Viscous Coupling Unit in the transfer case. So I've heard some people say the center diff is in the transfer case, and others the gearbox, and maybe both are right?

But what I don't understand is, there is two hollow shafts output from the center diff of the gearbox which connect to the transfer case. What I assumed was the inner hollow shaft was front wheel power, and the outer hollow shaft was the rear wheel power. But if front and rear power is split at the output of the gearbox, does this not have to mean the center diff is ONLY in the gearbox?

Anyone able to clarify my undoubtedly mixed up thoughts?

 

Here is my evo8 tranny..... the center diff is laying there on the left side of it..



not sure about other generation evo's but I assume tey are similar.
n

 

4-9 boxes. center diff in tranny. front diff in t-case.

 

What and where is the VCU?

And what type of center diff does an Evo use?

 

This should help a lot. It lays out all the parts in a color coded diagram.

https://www.evolutionm.net/forums/sh...d.php?t=149737

 

Thanks for your help so far guys. From the above diagram, to the right of the front diff in the transfer case, you see this note as per the diagram:

"(Black) This is the Center Limited Slip Assembly. It is in the same location on all Evos, but in 03 and 04 it is a viscous coupling. On 05+ Evos it is an active clutch pack that can vary the torque split between front and rear."

So my question is, we have two hollow shafts coming out of the center diff in the gearbox, presumably one is front wheel power and then one is rear wheel. So my question is, if we have the power out the gearbox split already, why is there more center diff stuff (VCU or active clutch) in the transfer case too?

How does the center diff in the gearbox interact with the stuff in the transfer case?

 

Basically, the differential in the gearbox is an open differential. The viscous coupling or active clutch (in the TC) is connected to both the front and rear outputs of this open differential and is what makes it a limited slip differential.

-Paul

 

Ah that explains my question. Thank you for that.