wobbly horns on 21H

[901chairman]

First time poster here. I have a 21H leslie retrofitted with 147 internals that sounds great with my A100. The only problem I'm having is the upper horns are wobbly enough to click on the wing nuts when the leslie gets up to speed.

The V21 is bolted in tight, but there is a lot of play in the horn rotors, and I'm not entirely sure what part I need to tighten this thing up. The V21 otherwise sounds great (no distortion) so I would like to fix it up instead of going down the rabbit hole of replacement drivers etc.

I have looked on the Tonewheel general hospital, but I am unsure about what it is I actually need to get my horns all tightened up. Has anyone else had this problem or know what to do to fix it?

[geoelectro]

Normally, the horn/bearing assembly fits very securely to the flange. Wobbling is usually the flange being loose. When new, the rubber grommets are fresh and hold the plate tightly. Over time, they loosen because of age and even oil causing them to get soft. The result is the plate is no longer held solid to the driver. Replacing the grommets should help stabilize the horn. The grommet has a spacer inside that stops the tightening screw from pushing into it. You can add a spacer under the screw/washer which will push harder on the grommet and add stability. I have used some reinforced felt and had it work very well.

Geo

[muckelroy]

There are 3 parts that "wear down" on the horn bearing:
-- The horn bearing itself (this is screwed in to the bottom/center of the horn assembly by 2 flathead machine screws, and it's a heavy/stout bearing, which accepts oil from the top hole.)
-- The thrust washer. (This is a thin wide washer that the horn bearing "rides" on top of
-- The spindle plate throat itself (the tube that the horn bearing slides over and on to.)

Those are your wear points. If any are over-worn, replace them.

As for spacers, you have 2 rubber spacers - one right below the metal thrust washer, and one that is glued on to the bottom surface of the spindle. The latter should be glued, and if the glue has come loose, the spacer also may shift, and wreak havoc on things.

Finally there is the large cardboard ring spacer that the V21 itself mounts to on the underside of the shelf. These typically don't need replacement if they are a consistent thickness all the way around. Worst case, the horn pulley "rides" at too high a level in relation to the motors, and that is when you may want to replace that ring.

The 3 spindle grommets are important too, but even if they fail, they should not cause so much wobble that the horn hits wing nuts. Still they are worth replacing if you're going through the trouble.

[David Anderson]

I agree with all said above. At this point, we often have no idea what someone has done as maintenance to these things over time, so you have to check everything. You need to make sure that the #6 screws attaching the spindle plate to the horn have aluminum spacers around them and large washers on the top. I have found those missing in the past.

People disassemble and reassemble Hammonds and Leslies all the time without putting them back together correctly.

One minor correction to muckleroy's comment is that 21H cabinets do not have cardboard spacer rings for the horns. They have wood spacers permanently attached to the shelf. Easy to forget that small difference :-)

[901chairman]

Thanks for the input, guys! I will disassemble this evening and look at the wear points, see if I am missing those washers, and hopefully find the right parts to get it going again.

I will post an update when I get it worked out!

[901chairman]

Update: Horns not so wobbly anymore!

I noticed that the deflector on the "dummy" horn was missing, causing the horns to be unbalanced. I removed the deflector from the other side (carefully so I could put it back if the sound changed substantially) and the horns spin more evenly now. I can't tell a difference in sound with the deflector removed, so I'm satisfied with this solution for now.

I have ordered some grommets for the horn spindle as well as a new belt that should tighten it up the rest of the way.

[muckelroy]

How loose is your belt? Is it so loose that the idler pulley can't keep tension? The idler is there to take up the slack. I only replace belts if they're hard and impacted with dirt, or frayed.. never because they're too loose.

[901chairman]

The belt is a little frayed, it has a flappy piece that adds a little noise as it goes around but its not too loose. The idler pulley is keeping tension fine but I noticed the belt was a little frayed when I got into it the other day.