Monday, 18 August 2014

ZCI/SHS piston comparison

Here's why I don't recommend ZCI nylon pistons. ZCI nylon on the left, SHS blue on the right.
there's a little congealed lubricant stuck to the ZCI
It's not all bad news for ZCI though.

In the first picture, you can see the shape of the metal racks for each piston. ZCI's is a solid block, while SHS's flanges on the side mean that the rack is supported by a much larger portion of the piston body. This is important to prevent this from happening:
rip ZCI piston, you weren't even being pushed that hard :(
The rack is only supported by a thin strip of nylon on each side, resulting in it easily caving in. ZCI's polycarbonate pistons don't have this problem though:
swiss cheesing mine, did not come stock like that
Instead of just two thin strips of plastic supporting the rack, the entire back of the rack has a layer of plastic preventing it from caving in. While I can't be sure how this compares to SHS' piston rack support method, it's definitely better than the ZCI nylon piston and has actually held up so far.
The support issue on the ZCI nylon may be "fixable" by epoxying the rack into place, but the ZCI polycarbonate costs the same and the SHS blue is only marginally more expensive and both would also benefit from the rack being epoxied in place, so why bother? 

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