I shot a couple videos on how to adjust a truss rod so we will not get into that very deeply here in this post. You can check the videos below for a step by step tutorial on how to adjust a truss rod.
What I want to cover here is a detail or two about the after effects of the adjustment. I find that after adjusting the truss rod on a guitar (particularly one that is far out of adjustment) it needs a little time to sort of “settle”. What I mean by that is this. Take for example you have a guitar that has a neck in an under-bow condition. After you tighten the adjustment mechanism the neck gets straighter and the guitar plays better. But what happens 12-24 hours after the adjustment? I notice that after the settling period the neck seems to usually drift further in the direction you were adjusting it. So in this example the neck gets even straighter or possibly back-bowed. I use the analogy of stopping a boat. You’re going along in your motor boat and you suddenly cut the engine. Yes, the engine stops but the boat keeps going for a bit until it glides to a stop, overshooting the point where you cut the engine.
To remedy this you can do one of two things. Adjust the rod to just shy of where you want it to be. Stop the adjustment before it gets to the perfect sweet spot so in the morning it will be where you want it. The other option is to adjust the rod where it is perfect and then re-adjust the next day. Why not do it one way and not the other? Well if you have the time you can adjust it shy and have it perfect the next day. If you don’t have the time because say you or your repair customer has a gig then you need to have the guitar play perfectly and then deal with the adjustment after the settling period.
Now here comes the tricky part. Not all necks drift past the adjustment after the settling period! So what do you do? This is where experience and some trial and error comes in. If it is your personal guitar you will get to know it from maintaining it throughout the years. Otherwise your tech will know how your guitar behaves to adjustments by his or her experience and taking care of it. Either approach will yield a great playing guitar!
So remember to be aware of this little detail when you are maintaining your guitar and adjust the truss rod accordingly. Get to know your guitar and all it’s anomalies so you can keep it playing at its best. The time is worth the investment!!!