I've never seen dual truss rods before and didn't even know they existed. Of course, this means remounting, restringing, and retuning between each adjustment. If that’s the case, depending on the design, you may have to remove the neck to adjust the rod (Fig. Follow the instructions in the relevant bridge manual to make adjustments. sure the guitar is in tune and the truss rod is adjusted properly. Look in the pockets of your case, your guitar often comes with the right tool for the job. Sometimes the access for the truss rod is at the heel of the neck. 3. Your truss rod adjustment nut may have an allen key, a cross head, a small brass nut or the rarer spoke hub type (as found on Stingray basses). The action may also need to be readjusted after the neck has been adjusted or strings have been changed to a different gauge. Your truss rod needs adjustment when the neck of your guitar has too much or too little upbow or too much backbow. If you know how to adjust the truss rod on a bass guitar, you can counteract those changes and keep your bass sounding great. Despite the fact there is information around the web telling readers to adjust their truss rod to raise or lower action, a truss rod is not for adjusting action. Adjusting the truss rod with a 1/8" Allen wrench. Vintage and vintage-style reissue Fenders, for example, require neck removal. Tightening or loosening the adjustment nut adds or lessens pressure on the rod and neck. Changes in temperature, pressure, and humidity can cause the wood to bend. The neck relief seems to be in spec a the moment, but this being Chicago on the cusp of Spring (it was 61° today) an adjustment is coming soon, particularly as I am planning on changing strings soon. Ibanez action is set at the 14th fret. Enter my new 5 string Ibanez BTB675 with twin truss rods! A truss rod is NOT for adjusting action. On the Ibanez RG we’re using as a test subject, the truss rod’s under the truss rod cover (no surprise!). 7).