Hope someone can advise. I have an EVO4 I use only for track use and it has started making a loud medium/high frequency noise in the rear end when under hard accelerating through corners for about the first 3 laps then it diminishes and eventually goes away till the next event some 30 minutes later. I know there are issues with these units. Any advice?

 

Throw away AYC and all corresponding hardware (pump, hydraulic lines, wiring, AWD ECU) and replace with RS diff. The car would be lighter, more reliable and predictable.

 

I was hoping someone might have had a similar problem. Yes I had thought of reducing the complexity by putting a LSD in.

 

Replaced the AYC clutch oil and also the application oil all bled and only heard the noise once and only lightly on the last track day so hope it has fixed my problem.