Bridge post looseness issue

[Eeyore]

Just to start, I've read and re-read Billy's leaning post post, my issue is not the one he describes exactly. Both posts/bushing are tight enough that I cant fit a shim inside to tighten it up (maybe I just need to find a thinner shim?).

Second preliminary is that the guitar works perfectly well in its current configuration. Which is a wood post making it a hard tail. Though it's been like that for so long, that there might not be much of a issue in floating mode either.

On to the issue. The bass side post has some loosness or slop in it, and this is present in 2 places. First, the threaded post down the centre of the bushing wobbles quite a bit compared to the treble threader insert. The result is the bass post is a bit less tight in the bushing than the treble post. But like I said, still tight enough that I cant fit an aluminum can piece inside as a shim. The second place is that the trem bearing on the bass side isnt as tight in the post as the treble bearing is.

The result is there is a bit more movement on the bass side of the bridge than the treble side. Its a none issue when set up as a non-adjustable hard tail, but may have present as tuning instability when using it in floating mode. The other observed issue is that when unstrung bridge shift/slide back and forth more than I'd like.

Are there any home-grown fixes to tighten up these two things? Anyone else have these issues?

[mmmguitar]

Welcome, @Eeyore (I relish any opportunity to say that).

If I’m understanding your post correctly, the rout for the trem posts is tight enough to be ruled out as the cause - but there is enough of a gap between the inner diameter of the one bushing and the post fitted into it that the post is wobbling when the bridge pivots; causing that whole side of the trem to shift when returning to zero?

In the worst case scenario, Mike appears to still have bridge bushings and trem posts (in case one or the other has somehow worn enough to cause this issue).

You’re right to want to confirm if a shim both alleviates and diagnoses the issue. If you happen to have any Teflon or copper tape, I would recommend seeing if a single layer wrap of either one around the post can be applied without the fit of the bushing squeezing it out. Of course, without the guitar in front of me, I can’t say for certain whether what you’re experiencing might be the result of any of the internal threads for the post being broken (which I only mention because I experienced that particular issue on a non-Parker guitar with a similar, bearing-pivoting trem design which was far less convenient to fix than Ken’s design).

I’m afraid I’ve only experienced the USM-specific leaning posts issue caused by the rout for the posts being too large in diameter - though It certainly produced similar symptoms.

[Eeyore]

The bushings are tight in the wood. And the posts are pretty tight in the bushings. The treble one is tighter than the bass side.

The bass side wobbles a tiny bit, but is tight enough that even thin polyamide tape won’t fit.

The two bigger issues is the bass side trem bearing. It isn’t as tight in the post as it could be. And further, the bridge slides back and forth between the two posts. The bearings sliding back and forth.

I’m thinking of putting lock-tite on the bearing to have it sit tighter in there.

I mentioned the threaded post in the bass bushing being wobbly. I don’t think that’s a huge issue, since the post fits reasonably tight. But tightening up the treaded post would give some piece of mind.

[Razoumihine]

Hello @Eeyore , i recently tried a fixing with home made half rings as on the picture. Although PVC was too soft, so i had to later us the shim technique proposed by Billy, i am sure that with harder material than PVC it is possible to make that half ring, adjust its size so that it fits like on the picture attached. Do you have the possibility to explore on this kind of fixing?
Regards,
Lionel

[Eeyore]

Not really. The issue isnt that the post is sticking too far out of the bushing. The biggest part of the issue is how tightly the bearing on the trem fits into the post, and to a lesser extend, that the screw part (threaded post in the bushing that adjust the action) is a bit loose.

I ordered a new post from the guy that was suggested. Perhaps it will fit the bear tighter.

[Razoumihine]

Ok, but, how the looseness of the screw in the post is an issue once the strings are in tension? I believe that once the strings are in tension, there is no more looseness or play no?

[Eeyore]

I'll have to check what it's when the trem is floating.

Right now I have a wood dowel in place of the spring and have it set up as a hard tail. The dowel itself keeps everything tight, and if I planned to only ever have it as a hardtail, I wouldnt be concerned. But I'd like to set it up floating again in the future.

When not under tension, the bass post does have a bit of wobble to it, which is why im a bit concerned about stability with a trem. However, tolerances are tight enough that my attempts at shimming didnt work. The Aluminum can trick didnt work, it was too thick. As was polyamide tape. I'll try with silicone tape/lock-tite.

It's hard to know if the looseness is just a level of slop that is within tolerance or if it's out. But the bass side does is less tight than the treble side.

[billy]

You might have two vintages of posts (or bearings).

Usm switched to metric 10mm OD. I believe the Ken era flys had imperial diameters.

Also possible is that the axle is in backwards in an attempt to compensate for some other issue.

The posts you ordered are almost definitely usm era so might be worth getting new bearings too. I am pretty sure I posted the bearing style and an amazon link for them too.

It’s not a hard job but you do have to be careful. If you push on just the outside race, the bearing will be damaged.

One additional thing to check would be how far the post can engage with the body bushings. Possibly you don’t have enough thread engagement as a result of some other issue.

[billy]

it’s been awhile but I think this is correct. Trust but verify.

Metric bearings USM
623ZZ (Inner Dia.=3mm, Outer Dia.=10mm, Thickness=4mm)

Imperial (prerefined)
R2-ZZ 1/8x3/8x5/32


You want shielded, not sealed. Sealed have too much friction.

[Eeyore]

Next time I change strings I’ll do some more investigation and take some pictures.