master cylinder finish

What is the usual finish for hydraulic master cylinders internal bores. Say a brake master cylinder. Would reaming be good enough? Material is 303

cheers T.Alan

Reply to
T.Alan Kraus
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Considering a brake hone uses stones of about 320 grit, I expect reaming would be OK

Reply to
Rex

Usually they are honed with a Sunnen hone. Usually the point is to remove any striations or rings (lines going either along the length of the cylinder or around the bore).

Reply to
woodworker88

Well, yes, but a certain fine finish is desirable, and a mirror finish is not.

Reply to
Rex

Yes I researched that and found out that there are two issues at play. One is the obvious piston seal deterioration by friction with a rough bore surface, the other is an increased stiction for the o ring seal when the bore surface is too smooth. These two issues work against each other and there is a happy medium. Somewhere I saw the figure of 20 micro inches or an Ra of 5. Can anyone confirm or shoot this down?

cheers T.Alan

Reply to
T.Alan Kraus

I wrote Raybestos tech dept, awaiting answer

Reply to
Rex

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