I have done it on two Escorts and I suspect it would be similar for your Focus. The two most difficult parts to do are:
1. Popping the axle shaft out of the transaxle. I wasn't able to pull or pry with a bar like the manual shows. I found that placing two strategically placed wedges between the axle and the housing and tapping on them finally released the axle.
2. Pressing/knocking/pulling the splined axle out of the hub was also difficult.
The rest is simple disassembly and reassembly.
Look to the LH directory here for general info.
Monday, April 30th, 2007 AT 6:50 AM