At Mishimoto we are big fans of our little blue car. Over the past few months you could say we have formed a bond that only burnouts and track days can build. In testing various Focus RS parts (and maybe doing a few donuts, for science) we noticed that it is very easy to make the rear differential in the RS angry, and you won't like it when its angry. The rear diff makes the rules. Overheat it, and you're likely to end up parked for the day. When the rear diff heats up, the ECU in the RS pulls power in an attempt to cool it down. Therein lies the problem: We have a car that begs to be driven to the absolute limits and rear diff that is programmed to shut down when it reaches a certain temperature. Don't get us wrong, the problem doesn't seem to be with the diff itself, but rather with its inability to dissipate heat fast enough to keep up with this blue bat out of hell.
Continue Reading »