It's one of those jobs that will take 5 times longer, the first time you do it. Whether to do it yourself or have a pro do it is hard to judge - it all depends on how mechanically inclined/experienced you are, how much time you have, and your tolerance for risk if you do something wrong. Plan on at least several hours, if not most of a day the first time, though.
On the other hand, we aren't talking about rebuilding an engine here, and there isn't that much you can do wrong. The critical things are getting the new seals installed (easy), getting the brake calipers re-installed (can be a bit trickier but not "hard" - you'll need blue LocTite for the caliper pins), and seating/loading the bearings correctly (not at all hard but
very critical). Beyond that, the biggest hurdles are jacking up and supporting the boat, and simply the mess. Your hubs take nearly a full tube of grease to pump full from empty.
When I did mine I wanted to change to a different type of grease (Mobil 1 Synthetic) and didn't want to mix it with the original. Once I had the bearings out I tried every solvent I had on hand to clean out the original grease. I don't know what that stuff was, but nothing would cut it. I checked with my local trailer shop and found I could buy all new bearings & races for far less than I thought possible, so I opted to do that. Here are your part numbers, in case you want them (it takes 1 of each to do 1 hub):
Inner bearing: Timken or Peer #25580
I.D. 1.75"
Inner race: Timken or Peer #25520
Outer bearing: Timken or Peer #15123
I.D. 1.25"
Outer race: Timken or Peer #15245
Seal: Victor #47017
Peer #POS2253337TBN
I.D. 2 1/4"
O.D. 3 3/8"
Thickness .375"
Dual lip, spring reinforced <-- That's important! They're cheap, buy a few spares.
On getting the old seals out, pry 'em out, beat 'em out from the inside, it doesn't matter if you're replacing them anyway; you won't get them out without ruining them. Just don't score the mating surface on the inside of the hub in the process.
If you ever replace the bearings, replace the races at the same time. Getting them out requires a long punch, a BFH, and a lot of pounding. A set of race drivers is a wise investment here.
I'll say this: Hub maintenance was one of the things I was the most concerned about for the first 1-2 years we owned this boat (all our tows are long). Now I give each one a few pumps of fresh grease once a year, scoop out and discard whatever that forced out, and don't worry about 'em other than keeping an eye on hub temps on long trips. I know I preloaded the bearings correctly and they've got grease.
That's a lot to type but it's not as hard as it might sound and you'll have more confidence in your trailer's condition when you're done. Just have LOTS of paper towels on hand.
