Gear chattering once warmed up?

[thongvua]

Hi folks,

I have an issue that has been bugging me. Once my m3 is warmed up, especially with A/C on and it's hot outside, it exhibits a whining/chattering sound that is most pronounced in the 2nd gear and gets louder as I rev higher.

I recorded the sound here, though it sounds a lot worse in reality. The chattering noise is most pronounced around 0:07 and 0:14 in the clip.

If you have any suggestions on what might be causing this noise I would greatly appreciate!

[mapster37]

very hard to hear, maybe try using a different device to record.

[thongvua]

Maybe this sounds a little clearer? It's the "eeeeerrrrrrr" noise that follows the engine rev.

I'm suspecting the Pentosin FFL-4 fluid might be the cause, so I'll replace the trans fluid to Ravenol MTF-2 next week to see if it helps.