Perplexing Truss Rod Issue

secretface · #1 07-13-2009, 02:03 AM

I put togather an all MIM bass recently (P-Body, J-Neck). The parts are all new and unused from E-Bay. I put it togather and set it up to fender spec no problem (action, relief, pickup height etc.) I noticed when it sits in its stand for 4-8 hours and I pick it up to play, theres a tiny ping sound from near the truss rod nut on the headstock. A few times of this happening and my relief and action increases. I tighten the truss rod to desired relief again and a few days later after some pinging, its too high again. I've gone through this now for three weeks and was hoping someone could tell me whats going on and how I could fix it. Is the truss rod somehow slipping incremently? Does it require a lube or something? I'm totally dumbfounded and would appreciate any help!

eli · #2 07-13-2009, 05:34 AM

Quote:

Originally Posted by secretface

I put togather an all MIM bass recently (P-Body, J-Neck). The parts are all new and unused from E-Bay. I put it togather and set it up to fender spec no problem (action, relief, pickup height etc.) I noticed when it sits in its stand for 4-8 hours and I pick it up to play, theres a tiny ping sound from near the truss rod nut on the headstock. A few times of this happening and my relief and action increases. I tighten the truss rod to desired relief again and a few days later after some pinging, its too high again. I've gone through this now for three weeks and was hoping someone could tell me whats going on and how I could fix it. Is the truss rod somehow slipping incremently? Does it require a lube or something? I'm totally dumbfounded and would appreciate any help!

Wow, weird. I have had this happen with my SX 5-string J (although never noticed any "pinging") and am interested to hear any fixes.

snappytom · #3 07-13-2009, 09:43 AM

Not sure about a fix, but the reason may be that the wood on which the truss rod nut sits (in the nut channel) is getting compressed when you tighten it. If all the parts are new including the neck this may make some sense. Perhaps it will settle over time.

billoetjen · #4 07-13-2009, 09:54 AM

Curious.

The ping you hear could be the sound of the nut slipping loose a small fraction at a time. Hopefully, Tom is right ad it's just the neck woods settling in.

secretface · #5 07-14-2009, 12:21 AM

The neck is from '08 and is vintage tinted with the serial number on the back. It came new from an ebay store that said it was unplayed. One thing I noticed the other day when comparing it to another MIM neck I own; if you look down that barrel towards the truss rod nut, it appears there is a miniscule gap between the wood and the truss rod nut. On the older MIM neck, it appears to have no gap in there. I dont know if that would cause anything or not. Maybe I just bought a lemon and I'm out $220....Ouch!

MIJ-VI · #6 07-14-2009, 05:13 AM

You are loosening the bass' strings before you make a truss rod adjustment no greater than a 1/4 turn every few days, correct?

secretface · #7 07-15-2009, 12:33 AM

I think the problem is/was the neck angle changing incremently. I took it apart and noticed a problem in the body's neck pocket. Where it was routed, it looked like someone went in afterwards with like a dremmel and routed a bit extra out at the bottom (same effect as shimming the pocket at the top). I sanded it to a smooth even surface and theres no room for the neck to move when installed. I'll monitor the relief for the next couple days but so far no more pinging sounds!