Originally Posted by Ginridge
OK, I was able to glean as bit of info from several similar posts (who knew there were that many Essex Basses with neck issues?). I was able to adjust the neck (Counterclockwise in this case) and re-assemble the bass. For the record, I don't think this has a double action truss rod as suggested in another post. It loosened but never got tighter in the other direction as other double action truss rods I've had did. Also, it did not take a 4mm neck wrench, Had to go bigger.
That and a bit a tweaking on the bridge feet will get me through the session. It's a demo only so I can take some time for a more serious set up later. I'm thinking neck shims...
Older SX basses don't have the double-action truss rod (which is not a rod but a stack of metal that warps one way or the other bending the neck.)
As you note the double-acting mechanism will get tight turning either way. A true truss rod will just loosen up. As for wrench size hard to say. Usually the one that comes with a new SX fit it. But used you just have to try them. I have two allen wrench sets...one metric and one SAE...Got em cheap at Harbor Freight tool store. You just try them until you find the right size. There seems to be no "standard" SX Truss rod wrench size. Once you find it, you go to a hardware store that sells individual allen wrenches and buy one (or two) in that size to throw into the case. In fact, what I do is go buy an allen wrench for ALL screws on the bass that take them...saddles, knobs, truss rod...whatever and make a little kit with screwdrivers that fit the screws (like say cover plate) as a little emergency kit to go into the case or gig bag.
The problem with some SX necks is that they are made flat. The string tension is supposed to pull them forward and the truss rod to bend them back where you want it. Sometimes they don't go farward enough! So the deal is you have to totally loosen the truss rod (until it rattles) and leave the string tension on the bass until the neck pulls forward enough. In resistant cases you have to tune all strings up a half or full step to get more tension on the neck and then let it sit a week or two.
I do have a couple SX where even after treatment no truss rod tension is needed. They play fine but you do need to put just enough tension on the truss rod to keep it from rattling, but not enough to back-bow the neck.