I have no help for you on the rack, but on the front struts, yes, you need to compress the springs to remove the mount (where the bearing is). If you have considerable mileage, you may wish to replace the strut.
The o-ring is the one between the resevoir and the pump - far from the rack and therefore doesn't matter when you replace it. Just remove the fluid with a turkey baster or something like it, remove the appropriate screws (no need to remove the hoses), and replace the o-ring.
|