will my 01 RS rear diff mate up with a 02 wrx tranny? I was under the impression that both were 4.11 and would be compatable.
according to my '02 FSM. the 2.0l turbo 5MT models had a 3.545:1 rear axle ratio..... only the WRXs with a 4EAT got the 4.111 diffs.
well...here's the thing. [tranny god speaks] One thing is your WRX tranny is a 3.900. The transfer gear is a 1.1:1, which is why they run a 3.545 in the back. This averages the rear to run like a 3.900; actual ratio is 3.8995. The rear diff will bolt up no problem, you just have to make sure it's the right final drive. If you want to run it like so with the 4.111 rear diff, sure, but your cetner diff VLSD will get HOT and the o-rings that seals it may die(crack, break, burst). The VLSD fluid is THICK and may or maynot mix with yoru tranny oil. You CAN however swap the transfer gear with an 99+ L/RS/Legacy/Forester transfer gear and find a 3.900FD rear diff off an '02+ Impreza TS/Outback Sport 5spd, 96-01 Impreza L 5spd, 96-99 Legacy 2.2L 5spd. These all run a 3.900FD. UNLESS you want to run a crazy setup like MINE, take the center diff vLSD guts out and you can run ANY rear diff FINAL DRIVE you want. Run a 4.444 rear and you'll get with your WRX tranny and that 1.1:1 a 40:60 split. [/tranny god speaks]
