I spent a while trying to install the inner seal on the right rear of my beetle yesterday, but I couldn't get it to go into its seat. It's easy to get it to go slightly in:
but then when I try to tap around the edge, the opposite part pops out and you're back to square one.
So I got a C-clamp big enough to squeeze the seal against the bearing housing, using two two-by-fours as flat surfaces:
This arrangement pushed the seal into its seat and got it flush with the outer surface
but that's not anywhere nearly all the way in. I need something about the diameter of the seal to push it in deeper.
As it turns out, the bearings are the same diameter. Here's the outer part of a roller bearing that I used to be just as big as the seal but no bigger
So I set up the squeezing mechanism with the bearing pushing on the seal and the clamp providing the squeezing force.
And only the second evening I worked on it, the seal is in!