This problem concerns an Evo IV but the drivetrain is functionally the same as the pre ACD Evo 8s.

When accelerating in the car there is definite slippage occuring, i.e the revs increase at a faster rate than the speed. It did not seem to be a clutch issue because there is no clutch smell whatsover after accelerating with the slippage, even after several repeated tries. Also there is no engagement issues, grinding of gears etc.

With the car on 4 jackstands, if it is started in gear, the left front wheel moves very slowly with a "ticking" stop start motion. The right front wheel spins okay and the two rear wheels also spin, but more slowly than the right front.

We pulled the transfer case off the car and inspected inside as it would seem to be either a centre diff or viscous coupling issue. Nothing looks out of the ordinary but it is difficult to see. We have not seperated the front diff. from the viscous coupling as it is not apparent how they are held together and we didn't want to damage anything. The Evo IV manual doesn't detail how to pull it apart. I haven't yet checked the VIII manual to see if there is more info. in there.

Does anyone have ideas as to what exactly is wrong?