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      06-28-2012, 11:32 AM   #57
mlhj83
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Drives: '11 E92 M3 DCT ZCP
Join Date: Aug 2011
Location: London

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When I had a new diff fitted under warranty, it made the usual groaning noises. I wasn't too fussed as I expected it, but given that it was pretty loud at low speeds on tight manoeuvring, the master tech decided it was best to change to the SAF-XJ +FM booster (83 22 2 282 583). FM being a fluorite based friction modifier. The noise disappeared.

I was initially hesitant about having the FM in my diff fluid as I believed that the FM would delay diff clutch engagement, but the tech assured me that there won't be a performance difference, which was proved by a track day soon after. I still managed to get power down very early on the outside rear wheel when powering out of a corner.

Last edited by mlhj83; 06-28-2012 at 11:38 AM.