Understanding the truss rod and how to adjust it helps you master your instrument setup. How does it work?
What is the truss rod and what does it do?
- Usually one (occasionally two) rods inside the instrument neck, anchored at one end with an adjustment on the other
- As you turn the adjustment (usually with an Allen wrench/hex key), it bends the rod more or less to counteract the force of the strings pulling the neck
- Tightening the truss bends back against the strings more (“arch”), lowering action; loosening it lets the strings bend the neck more (“bow”), raising action
Where’s the truss adjustment on your bass?
- Dave’s nice boutique bass 🙂
- I have an app
- Headstock behind the nut
- Fender and many other basses usually have this at the joint end of the neck where it’s bolted to the body
- With some basses you must remove the pickguard or the whole neck to adjust the truss
- Some others, like Music Man basses, have a wheel you can turn
- I’ve had neck-through basses that adjusted at the headstock, too
How often do you usually adjust your truss?
- Definitely every couple months, but I also leave it to feel – fighting action
- Sometimes I’ll play another bass and it’ll hit me like a ton of bricks
- Several times a year, usually when seasons change or it’s been a while since I used the instrument
How to do it?
- CAUTION: Small adjustments. Shouldn’t need more than ¼ turn for most cases, usually less
- If the adjustment turns loosely, see a qualified repair person; the truss may be broken
- DAVE: What does that even mean? I’ve always heard that but never understood
- Check action by holding a finger at 1st and 14th fret, and look at clearance at 7th fret
- For most people, should clear about the thickness of a good quality business card
- You can get more detailed than this, with precise gauges and slightly different heights per string, but it’s an easy rule of thumb
- DAVE: Feeler Gauge (for auto repair) at .015”
- DAVE: Also the capo on 1st fret vs using the elbow
- If you have to remove the neck to adjust the truss, do this order:
- Loosen the strings to slack
- Capo at the first fret
- Turn over instrument and remove bolts carefully with instrument supported
- Make adjustment, then restore and tighten bolts, remove capo and tune up to check action
- Otherwise you may be able to adjust with the instrument in tune — but note the adjustment will detune the instrument, so you have to retune
- If you have fret buzz at low frets on the neck, action is probably too low. If you have it at high frets, different adjustment (bridge saddles)
- DAVE: For those out there like me, don’t be above writing notes to refer to