I'm going to be rebuilding my clutch slave cylinder (new spring and piston). The fellow at the parts counter mentioned that I should use the finest possible hone when cleaning up the inside.

I looked into the process of cylinder honing and it seems that, for engine cylinders, it's important to get a cross-hatched pattern of "micro-scratches" that are at a 45˚ angle from the cylinder's vertical. This is supposed to support the oil and keep the rings well-lubed. If that is true, then given the different fluid and much lower speed and repetitions of the clutch piston, does it apply to the clutch cylinder too, or can I just give the inside a good general roughing-up?

1 Answer 1


The honing of an engine cylinder is done to help the piston rings bed in - the 45 degree angle of the honing and the 90 degree angle of the ring edge wear against each other and create a much tigher tolerance.

You don't need this effect in a clutch cylinder, in fact it would be detrimental as you have a rubber seal rather than a steel ring. I would have thought that you'd want the bore to be as smooth as possible to avoid anything that might snag on the seal and damage it.

  • This makes perfect sense, and is consistent with the advice I was already given. I wasn't actually aware that combustion cylinder rings were steel (although I had wondered how rubber could possibly work) -- I haven't gotten that deep into my engine yet.
    – jscs
    Commented Aug 9, 2013 at 19:23

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