Quote:
Originally Posted by Wonderboy
I talked to my father (pretty knowledgeable guy) about reusing the rings, and he was against it because the new rings have a noticeably stronger spring force when compressed than the old ones... according to him this is more important than the gap being spec. I really don't know either way as I'm new to this. I have no way of knowing and weighing the dis/advantages of having a new strong ring vs. an old gapless ring that still has a spec. gap. One thought is that it would be really interesting for one of us to use the old, and one use the new and dyno both of them right after break-in...just a wild possibility.
As for accurately removing .6mm - I'm not daunted. There are a lot of great tools at my parents' house including a metal lathe - I was thinking maybe I could use the metal lathe "backwards" by putting an extra fine grit stone from a dremel into the chuck and mounting a ring firmly where a bit would go, then using the measurement gauge to dig down to half the thickness of a ring. This may be more accurate than filing manually.
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He's pretty well correct. Spring force matters because no matter what the ring split gap is, if you don't have enough pressure to keep the ring seated against the cylinder, you've got a huge leak anyway. Ideal would be best spring force with an accurate/closed gap.
As with any spring-like object, the more compression applied, the stronger the spring force would be. That said, a used 76mm ring would still provide plenty of force against the cylinder, and may even drag a bit until it's worn in.
A digital caliper will tell you if you've removed .6mm, the problem will be removing half the thickness of the ring on each side, not removing material into the circumference.
Mark the ring, wrap it with some electrical tape, and try to sand/grind it as flat as possible to half the original thickness, then flip it over and make a matching side. You'll need to go further than .6mm, to account for expansion from heat and movement from loading.