HarryJS Posted January 19, 2018 Share Posted January 19, 2018 New to the forum and although this has probably already been asked I don't yet know how to look for it on the site so I'm asking now......I just purchased a 1993 Gibson J-45 fro a private seller and when I looked at the truss rod adjuster it is different than my CL-20 in the sense that the truss rod nut seems to turn the entire truss rod where as my other gibson the nut rests against the top of the neck and the pressure is against it. My question is this: does the entire rod turn on the 93 for adjustment? or is it not functioning correctly? Thanks in advance.....also how much pressure should it take to make the adjustment for lowering the action Link to comment Share on other sites More sharing options...
jvi Posted January 19, 2018 Share Posted January 19, 2018 truss rod isnt for full action adjustments and if the entire rod turns you likely have trouble, perhaps showing someone with knowledge should be your next move Link to comment Share on other sites More sharing options...
kidblast Posted January 19, 2018 Share Posted January 19, 2018 Harry, not trying to be a dork here but, take it some where, I don't think working this out seems in your wheel house. FYI that the truss rod is to set the relief on the bow of the neck, it won't really impact the action over all. Action is changed on an acoustic by removing material from the saddle, and some corresponding adjustments to the nut / nut slots. It sounds like something is not quite right based on your description posted. There should always be a little bit of tension on the nut to loosen or tighten. Also keep in mind, that no truss rod adjustment you make should ever exceed 1/2 to 3/4 of a turn. if it's spinning around 360 degrees with no tension, there is something off there. Link to comment Share on other sites More sharing options...
Hogeye Posted January 19, 2018 Share Posted January 19, 2018 Your guitar has a "Double Action" truss rod. The entire rod is made to turn. The adjuster nut is brazed to the rod and the whole thing turns If you turn it clockwise it makes the rod shorter thus changing the neck. If you turn it to the left it will adjust the neck in the other direction. The double action truss rod was fine for banjos and instruments with slimmer necks but the guitar neck is too beefy for it to do the job it's supposed to do. Gibson only used it for a short time. It was much against the advice of the Master luthier but the General Manager thought he knew better. Take your guitar to a qualified repair person and he can adjust the rod for you. If you back the rod out to far you will turn it right out of the nut that is embedded in the base of the neck and you may not be able to get it to rethread again without taking the fret board off. There is nothing wrong with a double action truss rod if you know what you are doing. There are a lot of them out there and when they come to light only the best repair men know how to adjust them properly. Proceed with caution. Link to comment Share on other sites More sharing options...
Dave F Posted January 19, 2018 Share Posted January 19, 2018 My ‘94 Jumbo has the same rod Link to comment Share on other sites More sharing options...
mz-s Posted January 19, 2018 Share Posted January 19, 2018 Small turns are your friend. As others have said truss rod adjusts relief, not so much action. But it will affect action towards the middle of the neck. I measure relief by fretting first and 14/15th frets, then seeing how much space is between low E string and the 7th fret. You want a small amount of relief, enough to fit a few sheets of paper under the string - 10 thousandths or so, or less. No space means the neck is either perfectly flat, or is backbowed. 1/8th a turn at a time until you get it where you want. 1/4 is a big adjustment. 1/2 a turn is a huge amount. It will take a bit of force, similar to the amount of force required to screw a into your wall. Link to comment Share on other sites More sharing options...
Hogeye Posted January 19, 2018 Share Posted January 19, 2018 My ‘94 Jumbo has the same rod Hi Dave What is the date of your guitar. I remember the double action going in the guitars around the early to middle part of '93 and then they mercifully went back to the single action in about the latter part of '94. Maybe you could help with another bit if info. The same general manager was trying to reinvent the whole Gibson build and he lacquered the inside of the guitars as well as the outside. The thinking was that this would stop the humidity changes from cracking the wood. All it did was completely alter the sound. This brainstorm didn't last long either. Could you please look at the interior of your guitar and see if it looks like it has been "sealed". It won't be shiny or glossy like the outside but it won't look like raw wood either. The braces weren't sprayed just the top, backs, and sides. It's pretty easy to see. I think the guitars were from late 1993 to middle 1994 era. Your guitar might be helpful in getting the times these changes were made. Thank you. Hogeye Link to comment Share on other sites More sharing options...
j45nick Posted January 20, 2018 Share Posted January 20, 2018 Maybe you could help with another bit if info. The same general manager was trying to reinvent the whole Gibson build and he lacquered the inside of the guitars as well as the outside. The thinking was that this would stop the humidity changes from cracking the wood. All it did was completely alter the sound. This brainstorm didn't last long either. Could you please look at the interior of your guitar and see if it looks like it has been "sealed". It won't be shiny or glossy like the outside but it won't look like raw wood either. The braces weren't sprayed just the top, backs, and sides. It's pretty easy to see. I think the guitars were from late 1993 to middle 1994 era. Your guitar might be helpful in getting the times these changes were made. Thank you. Hogeye My 1947 L-7 archtop was completely sealed on the inside, I assume with a low-gloss lacquer. First time I had seen that. Link to comment Share on other sites More sharing options...
Dave F Posted January 20, 2018 Share Posted January 20, 2018 SN 90624xxx looks like early March 1994 Picture above looks like it was sprayed. I never noticed that before. This was one of the guitar of the month for March Link to comment Share on other sites More sharing options...
Hogeye Posted January 20, 2018 Share Posted January 20, 2018 Thanks for the reply Dave. I believe they stopped spraying the insides toward the end of 94. Gibson never announced that they were doing this and they never announced the dates of stopping the practice. The lacquer was sprayed on the guitar parts before they were made into bodies. They used regular lacquer. They received one thin coat of lacquer and were not buffed so they are a bit difficult to spot. Most serious builders believe this is not an acceptable practice as it prohibits the wood from drying and ageing normally. There were a lot of goofy things going on at Gibson at this time as the G.M. was trying to make a name for himself as a innovator. He wasn't and all his experiments were short lived. Link to comment Share on other sites More sharing options...
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