This is the procedure I used:
1) Complete tear down; even the differentials
(not to be confused with the bulkheads)
2) Top off the differential with 30K
(or whichever weight you want to use. 30K is stock)
3) Clean excess grease off of ring and pinion
4) Clean up the interior of the bulkhead
5) Add 4 shims to proper side of differential between bearing and differential.
(not bearing and bulkhead)
(my reason for this location: this side of the bearing is greased, allowing the shims to slide on each other; hopefully not wearing down their thickness)
6) Install internal parts of bulkhead
(differential, pinion, ect)
7) Lightly lubricate the ring and pinion with a dry lube.
(this is to help resist the attraction of dirt)
8) Bolt up the lower skid plate
(it holds the bottom half of the bulkhead together)
8) Install long bolt holding two halves together
(snug it up, do not over-tighten)
10) Spin the drive shaft attached to the pinion. It should spin with slight resistance. If you have to work to spin it, there are too many shims. Remove one shim, repeat the process.
With that being said: mine spun nicely except for one spot where the teeth on the ring had a few nubs. In that location, it was more difficult to spin, but not hard to spin. If that makes sense. lol
This is how I set mine up. I have had 0 issues with gear mesh... no clicking, even when slamming it into reverse or forward while it is still rolling. No issues with binding either. When I set it up, my theory was that the new ring and pinion need to wear into each other while pushing the flex of the plastic bulkhead near its max.
I ended up with 3 shims in each bulkhead.
Associated 21141. They come with 4 shims per pack.
I have yet to tear it down to see how things are wearing into one another, but I imagine that the tooth surfaces of the gears are shiny. Just as they are in a properly meshed 1:1.
Oh, a few more tips:
1) Pay attention to what side the ring is on in the bulkhead!
2) After setup, I did not go out and run a full pack through it. I ran it a little, then let it cool down. This might not matter at all, it is just how 1:1 gears are broke in.
3) Take your time. Don't be rushed. Setting this up properly will save you in the long run!