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Is there a decent way to test a rotary valve to determine where the tolerance may be too low? I am messing around with some fairly tight valves and I am curious if it is catching at one bearing or the other, or if it is maybe hitting on the valve cylinder itself.

Also what is the safest method of scrubbing out crud from a rotary valve and plate thoroughly without doing any damage? I have been using a brush and toothpaste as a very mild abrasive but it sure as heck requires a ton of elbow grease to go with it.

Ouch.

I use the normal method for cleaning rotor components... scrub them with a toothbrush and Dawn to get the oils off and them drop them in the chem-clean solution until the green/white-ish stuff is gone.

Once the valve is assembled correctly, aligned, and the certain the back bearing plate is seated... note any drag. If the drag is severe and doesn't clear up with rapping/tightening the back cap and maybe a tap on top of the rotor screw.... take the rotor back apart and look for drag marks on the rotor and inside of the housing.

If you see drag marks.... repeat the assembly process until you are certain there is a clearance problem. Once you determine there is a clearance problem then there are multiple ways of dealing with them depending of exactly where the drag is. This can be a complex issue. It could be resolved with swaging the bearings or some mild lapping.... or both.

For determining if there is TOO MUCH clearance in the rotors... a simple 'pull the slide and hear a pop test' will work unless the rotor is vented. In that case you'll have to locate the hole in the rotor housing and cover it with your finger before pulling the slide on that rotor. If you don't get a 'pop' use the same heavy oil test as you would with piston valves.

What chem-clean solution do you suggest?

Your tip about tapping the back cap for alignment has been very useful to me in the past (although once I tapped it down when it was cross threaded - luckily no damage).

Thanks.

chronolith wrote:What chem-clean solution do you suggest?

Your tip about tapping the back cap for alignment has been very useful to me in the past (although once I tapped it down when it was cross threaded - luckily no damage).

Thanks.

Yeah... you've got to be extra careful with those fine threads!

For lack of professional chemistry.... use white vinegar in the same fashion as you would clean the hard water deposits from a sink or tub drain. It might take a couple of hours for heavy deposits to go away completely but even soaking overnight in vinegar won't hurt anything.

Something like CLR will work a little quicker but I wouldn't advise leaving it overnight.

^ Or you could just use some warm water, Ajax or Dawn and a steel bristle brush to scour off the calcium/lime deposits and be done with it

toobagrowl wrote:^ Or you could just use some warm water, Ajax or Dawn and a steel bristle brush to scour off the calcium/lime deposits and be done with it

Steel brush on brass???

MartyNeilan wrote:

toobagrowl wrote:^ Or you could just use some warm water, Ajax or Dawn and a steel bristle brush to scour off the calcium/lime deposits and be done with it

Steel brush on brass???

Maybe this is the Friday funny on a Friday !!! The pumice in the Ajax might take up permanent residence!!!

Some people REALLY should take their tubas to somebody who knows what the hell they are doing!

toobagrowl wrote:^ Or you could just use some warm water, Ajax or Dawn and a steel bristle brush to scour off the calcium/lime deposits and be done with it

Operating principle here is "done with it," for sure.