Why aren't regular snap rings used in place of spirolox retaining rings?
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coloradohill
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They can be. They're just a different form of retainer. Early hemis, polys and slant sixes used them. Might be more. I'm unsure the factory ever used Spirolox.
junkyardhero
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#not all motorcycle pistons
Is because, You haven't seen yet what can go wrong with a common retainer, used in an abusive environment. Spirolox won't break or fall out, a regular offering can cause a worn slot/trough gouge in the cylinder wall when it fails. Correct orientation of the end gap of a common retainer can prove to be verry beneficial. Never put the end gap of a regular clip at or near the 3 'o'clock or 9 o'clock placement. Centripetal force factors come in to play. They will fatigue if so. 340's (high revers) and 390 fords (turds) are usual culprits of this type of failure. Pics include the 1 type that can fail/ break and the type that can fall out, (pic to follow when I find it).
junkyardhero
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in common 2T parlance: coughing a clip and wasting the barrel
i was taught open ends to the deck and never re-use clips.
generally stock use the circlip so, we're talking sub 7K ish rpm, most aftermarket use some type of wire clip: C, G, or double loop. and something a lot of people mess up is substituting clips thinking "if it fits, it's good enough" when in reality the trough in the piston is machined differently for different clips-- specifically c-clips v wire clips.
WTF. I still cant link it , photo'd my comp screen, these are "wire" clips. same thing goes, DON'T put the end gap at 3 or 9 o'clock position. they usually won't break, but not putting the end gap where the least amount of recip force is involved is beneficial.
How can a snap ring "pop out" since it's under pressure?
I had 2 blocks, a 360 and a 73 340, that the snap rings have popped out from the factory and the wrist pins scored the cylinder walls. I have never had a spirolox pop out.
junkyardhero
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Centripetal force.
a net force that acts on an object to keep it moving along a circular path. any object traveling along a circular path of radius with velocity experiences an acceleration directed toward the center of its path, a = v 2 r
my rocket scientist friend explained it to me, a dumbass mechanic, thusly: imagine bouncing a round rubber ball on the concrete floor. when it hits, it deflects and the "circle" now becomes deformed and oblong, and that energy has to go somewhere, so if the C shape is perpendicular to the "floor" as the circle deforms it closes the gap of the C. it doesn't always spring back into place. and that ball bounces 166 times a second*.
eta: on the 166 # i forget what rpm that was calculated at, but rest assured it was dead on balls accurate; the dude sent a rover to mars.
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I do not think it has any thing yo do with centripetal....or centrifugal force.
The reason is more simple. The 'C' type circlip or snap ring with a circular cross section is not as secure in it's retaining groove as a rectangular section snap ring or spirolox.
The piston pin 'hammers' the retaining device & a round circlip in a round bore is easier to displace than a circlip with a sharp edge. Another contributing factor to round section circlips moving out of place could be insufficient depth of the machined groove.
The reason is more simple. The 'C' type circlip or snap ring with a circular cross section is not as secure in it's retaining groove as a rectangular section snap ring or spirolox.
The piston pin 'hammers' the retaining device & a round circlip in a round bore is easier to displace than a circlip with a sharp edge. Another contributing factor to round section circlips moving out of place could be insufficient depth of the machined groove.
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