There are some older books on the market that are cheap and do a great job. I would have to do research to find some book names (and I’m feeling lazy right now).
Getting a FSM (Factory Service Manual) is a must.
Automatic Transmissions are very picky about dust and dirt, more so than maybe anything else on the car. Even the lint from paper towels can/will give issues.
Working off of a clean work bench is a must!
What I do is I set out either two work benches or two folding tables (if doing this at home). I then place clean/fresh cardboard on top (it protects tables and parts also helps absorb fluid). Have extra cardboard close by (I like to change it out after disassembly of transmission and after cleaning of parts.
You will also need a place to clean parts (but not close to where you are working from).
Most internal parts generally don’t need much for cleaning, for the most part – unless you really cooked it.
Get a big bundle of shop rags. They are fairly cheap, and don’t attempt to wash them afterwards (or your better half will have your head out for public display in your yard). Paper leaves lint which is a transmissions enemy #1.
It might help to take your pages and photocopy them then place in clear page protectors – so you don’t have to worry about getting them oily.
Special tools that you may or might not have (not a complete list).
A camera, a slide hammer (for removing front pump). A cheap impact Phillips screwdriver (for the two small screws under transmission mount). A steering column lock plate tool and all-thread (to make a small press for clutch packs), several snap ring plyers, feeler gauge, A small tub to put ATF in to soak your transmission clutches (maybe others, that I can’t recall off of the top of my head).
Note: transmission clutch disks are made of paper (yes, paper) and they MUST soak in ATF a while before installation or you WILL have clutch failure very quick. I recommend soaking them overnight as well as soak your bands).
When taking the unit apart, place the parts on your other table, in order you remove them. Numbering the parts (on cardboard) might not be a bad idea.
In most cases, the bushings and thrust washers may show wear, but for most people, your old bushings and thrust washers should be within specifications.
If bushings are loose, then changing the bushings can be fun – but is doable at home.
If you leave for the night, be sure to cover your parts. Getting a cheap twin bed sheet set (at a dollar store) and wash it first, works great.
The bed sheet and cardboard are meant to be disposed of after overhaul.
Cleaning/rebuilding the valve body is maybe the hardest part.
It not hard to do, but there are so many little parts like valves, springs and ball bearings (check valves) that can scatter or get mixed up and the such. Just take your time, lay out things in order of removal, take lots and lots (and lots) of pictures. Take your time. Make sure each valve moves freely in each bore. And lastly, take your time.
The valve body IS a hydraulic computer.
Personally, if transmission was shifting fine, before it started to slip (or make noise, etc.) I would recommend to just leave the valve body alone.
There are about 200+ moving parts inside of the valve body, and most of the parts, springs, check valves, etc. all look the same (but not quite). It is very easy to lose a spring or get other items mixed up. There is no good diagram on which spring goes where, what direction valve 73 goes in and so forth.
Lastly, don't wear good clothes.
BudW