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My mirafone 186 is about 3 or 4 years old. The cork bumpers are crumbling a little, and I am going to replace them in the future. Would you suggest getting one rubber one and one cork on each valve, or replace all of them permanent neoprene bumpers?

I use one of each on each rotor. Just a preference of mine

how long should the cork last me?

The guy at osmun brass told me that the neoprene was permanent. I have heard that the neoprene causes the valves to bounce a fair amount...is that true?

bloke wrote:

mTaUrBkA wrote:The guy at osmun brass told me that the neoprene was permanent. I have heard that the neoprene causes the valves to bounce a fair amount...is that true?

I ainsk no physicisckst, but I would bet that rebound-bouncing against the hard neoprene bumpers might have something to do with low-mass/weight linkage systems vs. high mass/weight linkage systems (inertia, etc.)

Explain why I'm not right, Rick(D)/Chuck(G).

bloke "who is probably wrong"

What you need is some REALLY GOODbumpers http://www.hendrickson-intl.com/products/components.asp

Vacuum Cleaner Belt

It doesnt suck

When I take the tuba in for bumpers I should get a new one on my trombone f attachment as well......I completely forgot about my tin foil last minute solution!

mTaUrBkA wrote:The guy at osmun brass told me that the neoprene was permanent. I have heard that the neoprene causes the valves to bounce a fair amount...is that true?

Thats why I went to cork on the return side. It doesn't bounce as much

The neoprene bumpers on my CC horn proved to be soluble in valve oil (Is that a word? They disintegrated when they got in contact with the oil, forming a kind of powdery paste that would make its way into the valve. SHUDDER).
I replaced them by pieces of sealing rings. Hetman´s #15 oil solved the clanking problems the linkages had.

tubeast wrote:The neoprene bumpers on my CC horn proved to be soluble in valve oil

This is the reason I have commented several times about using O'ring stock for bumpers. O'rings are generally made of Viton or Nitrile rubber... which is highly resistant to oils, fuels, and solvents. You really have no idea what other items like vacuum cleaner belts, pencil erasers, or weather stripping are made of.

The need to be resistant to oils pretty much lets me know why cork was the original choice for bumpers. Materials available even as recently as 100 years ago were pretty much limited to those found naturally. Natural rubber is NOT a good candidate for use around oils. Cork was (and is) plentiful.

thanks for the input everyone!

mgilbert wrote: Anyway, Bloke, Dan, Chevy, et al what do you guys think of silicone bound to cork? Is this going to work? Fail?

The only way to get the answers you seek is to try it out. However, I think you are perhaps going to a lot of trouble for nothing. It's not likely your rotor noise is coming from the bumpers... unless the bumpers are missing completely and the stop arms are backing into the stop plates.