When I put my savox into my cr2 it did exactly the same-fouled on the balljoint.

(Though I had the ball joint on the other side on the servo horn-facing front). The savox servo case is slightly bulkier in that area compared to a ko/sanwa servo.
Only way round it is to dremel a little material off the servo case-I've seen it done-and it works-but I didnt fancy doin it to my brand new savox-hence I sold it and bought the new small Sanwa servo( which is perfect and leaves more room behind also for speedo's / weights etc. )