Tremelo Arm Bushing

[Gregsaab]

I have been struggling to get my pre-refined trem arms working as I would like them to function. The issue that I am having is that the bushing is consistently too loose, which allows for the bushing pivot collar to move each time I use the trem. This causes unwanted noise during use, plus it’s probably adding needless wear on the threads.

When I tighten the bushing (using an allen key from back of guitar), the arm’s rotation is way too tight and the bushing loosens back to a floppy state within minutes. For the tightness issue, I have loosened the set screw on the trem block as much as I was comfortable doing (the placement of that screw is probably the only design flaw of the pre-refined, imo).

If I wanted a tight pivot with an arm that could freely rotate, what would I need to do to accomplish that?

[vjmanzo]

Hi @Gregsaab—have you tried slightly bending the part of the arm that sits in the bushing? You can do this by pressing the arm forward in the bushing while holding the bridge in place.

IIRC, the pre-refined bushing itself does get narrower further down, so bending the arm slightly might allow it to go deeper into the bushing and create more surface contact with the walls of the bushing thereby keep it in firmly seated in the bushing while allowing it to rotate freely as set by the set screw.

Am I understanding the problem correctly?

#VibratoBridge

[Gregsaab]

The arm fitting snuggly within the bushing is not the problem that I am talking about - I’m talking specifically about the bushing itself moving when it is not snuggly tightened. I am trying to keep that bushing tight, but allowing the arm to freely rotate.

[vjmanzo]

Got it. Thanks for clarifying.

I’ve not experienced that issue myself. I suppose it’s possible that the set screw is stripped/worn. Are you able to take it out and examine it?

When I tighten the bushing (using an allen key from back of guitar), the arm’s rotation is way too tight and the bushing loosens back to a floppy state within minutes.

The bushing shouldn’t, in principle, loosen up within a few minutes.

[Gregsaab]

Got it. Thanks for clarifying.

I’ve not experienced that issue myself. I suppose it’s possible that the set screw is stripped/worn. Are you able to take it out and examine it?

Yeah, I will take a peek later!

[Gregsaab]

Would a loosened set screw should allow for a low-friction rotation (e.g. freefall)? Or, is that not possible?

Here is a video of play in bushing https://www.icloud.com/sharedalbum/#B2NGzFCC1GA7Gwj

[mmmguitar]

@Gregsaab, the good news is that this is a straightforward fix - The bad is that you're liable to find you need to remove the bridge from the guitar to do it, if there's corrosion or anything else necessitating elbow grease (I'll say a small prayer for your blood pressure if you try to fight it with the bridge still in the body). Basically, you need to tighten the threaded fastener nut on the other end of the vibrato arm bushing - The problem is that it's round; meaning it will be tough to get a grip on the bushing from each side:

The two part bushing consists of a sleeve (with a button head on the collar-end, and threading on the other) inserted from the topside of the bridge, and a round fastener which threads onto the sleeve's protrusion on the underside of the bridge.

I decided to snap a photo of the disassembled parts for reference.

In your case, you need only thread the nut on more until the fitting is better secured; and the room for your symptomatic wobble is eliminated - For reasons I'll elaborate on below, be mindful to not over-tighten it. The steps I came up with in my testing are:

1. Remove the set screw from the trem, and set aside in a safe place.
2. Insert a hex key (or the vibrato arm, if you can't find a key that fits) in the collar-end of the bushing, and
3. grip the nut end of the bushing with channel lock pliers or vice grips with a cushioning material between them to minimize scratches (in my case, an eyeglass cloth within reach was sufficient).
4. While squeezing the nut with the pliers firmly enough to prevent it from rotating, use the hex key inserted into the collar-end of the bushing as a crank to turn the bushing toward yourself (in the manner illustrated above) to tighten the assembly by threading the nut further onto the bushing sleeve (the opposite direction will, of course, unthread the nut).
5. Then, check the friction of the bushing fitting with the next step:

Using the vibrato arm inserted into the collar (with the set screw still removed), test whether the resistance the bushing is rotating against feels sufficient. If you tightened the nut too much, the bushing will not want to rotate; and you must repeat step 4, but turn the key in the opposite direction to loosen the fitting until you find you're happy with the amount of resistance.
6. Reinstall the arm tension set screw. Depending on how tightly you fastened the bushing assembly against the underside of the bridge, the resistance imparted by the set screw may be redundant unless you prefer the bushing loose enough for the bar to swing down toward the floor when not held (at which point the resistance imparted by the set screw can be used to compensate for the looser fitting of the bushing to an extent).

[Gregsaab]

@mmmguitar you’re the best - thank you for that informative post, that makes so much sense, I knew I was missing some info on the mechanism. I think this is going to push me to install my Ghost saddles that I’ve had sitting around. This saddle install will be easier than last…

[mmmguitar]

This saddle install will be easier than last…

Well yeah - I won't be there to mislead you about the shielded single conductor wire running from the bridge to the preamp input!

[vjmanzo]