Can someone walk me through setting the preload on the rear shock of my ds. Been eating up chain rollers and some of the metal above where the chain roller should be. HELP.

 

Tighten preload adjustment (double nuts on top of shock springs) to achieve between 3 and 4 inches of sag when you get on the seat. First, measure from grab bar to ground, then get on, measure again. The difference between the two is sag.
If you're a really big guy, you'll have to tighten it quite bit from the stock setting, and you should shoot for 3" of sag if you're like 300lbs or more, 3.5-4" if you're around 200lbs.
You'll notice that as you tighten it, the measurement from bar to ground without rider will keep increasing with every turn of the nut, but "sag" will not start decreasing until you have cranked it quite a ways. Keep tightening it until you get to the mentioned sag, and by the time you get there you will notice the rear of the bike sits a bit higher, helping to keep you off the chain roller.

Next, buy a new chain roller made by TM Designworks - it will be the last one you need to buy. Double row of bearings inside, $39.99