Conn 4J 4th Valve Stem Replacement

[jonwatso]

All,

I think that one of my daughters, during a cleaning project, managed to bend my 4th valve stem (which now brushes into the edge of the valve cover cap), making it stick.

I tested the valve using a stem from the third valve, and it functioned fine.

Doing research, my 4J was made using similar tooling to the Olds 99-4.

Has anyone replaced one of these before? What worked as a part?

Also, assuming I should get new corks and felts, as a matter of course?

Thank you!

--Jonathan

[gocsick]

Have you tried just carefully bending it back???? If you are worried about trying it you friendly neighborhood brass guy should be able to do it for cheap, and replace your corks and felts too.

[bloke]

Could it be bent back?
That's what I usually do.
(I believe you would have luck straightening Olds or King stems and what do you think, but probably not with any of the new ones which hold those plastic valve guides on to the tops of the pistons. All of those newfangled ones are really fragile and would probably break - right down at the threads.)

I'm suspicious that the Olds valve stems (which are sold by Allied supply to repair shops) are actually Holton valve stems.
They fit the Holton 345 tuba pistons perfectly, and.it seems to me that they screw in a little bit too deeply into Olds pistons - which defines them as being slightly too short.
The so-called Olds (from Allied) seem to need a little platform brazed onto them just above the threads (very similar to King valve stems) in order to stop them from going in too far.

[jonwatso]

Have you tried just carefully bending it back???? If you are worried about trying it you friendly neighborhood brass guy should be able to do it for cheap, and replace your corks and felts too.

I've been reading about that. I'm a little nervous, so I might just take it down to Mark Metzler and have him straighten it and clean the rest of the instrument and test the compression.

[jonwatso]

Could it be bent back?
That's what I usually do.
(I believe you would have luck straightening Olds or King stems and what do you think, but probably not with any of the new ones which hold those plastic valve guides on to the tops of the pistons. All of those newfangled ones are really fragile and would probably break - right down at the threads.)

I'm suspicious that the Olds valve stems (which are sold by Allied supply to repair shops) are actually Holton valve stems.
They fit the Holton 345 tuba pistons perfectly, and.it seems to me that they screw in a little bit too deeply into Olds pistons - which defines them as being slightly too short.
The so-called Olds (from Allied) seem to need a little platform brazed onto them just above the threads (very similar to King valve stems) in order to stop them from going in too far.

The problem with an old instrument, right?

Maybe find another 4J and cannabalize it

[bloke]

- Buy a stem from Allied.
- wrap a piece of "soft wire" (steel) into a circle (which fits tightly around the new stem)
- silver-braze the wire onto the stem
- (probably) a little bit of filing and clean-up
- install
OR
- make one out of some stock cylindrical (1/4 inch) brass, as 1/4 inch is large enough to leave that shoulder at the bottom.