Thanks guys, that helps a lot.
I have a few questions. Should I be removing the s-cams and slack adjusters regardless, or clean everything, see if I can get it to take grease, then make sure they move freely and only remove if it they don't? How do I back the slack adjusters off being that they are auto slack adjusters? I never looked but is there still that nut to turn them like the manual ones? I don't know if it makes a difference, but picture was taken with caging bolt turned all the way in.
The drum has very little wear not where i'd say it needs to be replaced, there is a tiny ridge where the shoe ends, but not much and there is tons of thickness left, I attached a picture but don't think it will show much. I have receipt from old owner showing mid 2014 all new drums and shoes done, and last time trailer was inspected. The shoes didn't even seem that worn, just the very back of both pads, the rest had lots of life left. I measured diameter of drum and it is smaller then the max diameter. I don't know how to verify if it's the correct drum though? They are 17.5" wheels and drum says 12.25x7.5". The one thing I did notice is the receipt from old owner shows drum price at double what I was just quoted when I picked up the shoes, they quoted the drum off of me just bringing in old shoes, not seeing old drum so maybe it is a different drum? Speaking of that I attached a picture of the studs, the parts guy said they are wrong and used for aluminum wheels (mine has steel), they look funny to me because they are so long, which is why I think I had such a problem getting the lugs off because there is so much thread to get full of junk and ruin the threads. However, all 6 wheels have all the same studs so I doubt on a 2012 trailer someone would have already replaced every single stud? Considering I was told $1000 to replace all studs and nuts.
The oil was dirty, but every wheel is full to right level, and hub turns nice, no sign of oil on shoes at all. Should I also be pulling the bearings to actually check? I was worried about having to re-torque that nut as I don't know if my torque wrench goes that high. Wheel seals would mean pulling the bearings as there's a inner and outer correct?
I want a safe trailer that won't give me problems getting pulled over, but at the same time I might put 2,000 miles on it a year, so if I can get by with the drums i'd prefer that, instead of spending another $1000 on them. I bought new pads and hardware kits for all wheels though.
Sorry if some of my questions are dumb, it's been about 7 years since i've done air brakes, only only ever done them once so not very familiar with the setup.