{"id":21878,"date":"2023-02-09T09:55:12","date_gmt":"2023-02-09T00:55:12","guid":{"rendered":"https:\/\/www.decoboco.info\/en\/?p=21878"},"modified":"2026-09-24T13:46:18","modified_gmt":"2026-09-24T04:46:18","slug":"zephyr-750-additional-brake-caliper-oh-inspection-shell-engine-oil-change","status":"publish","type":"post","link":"https:\/\/www.decoboco.info\/en\/20230209\/everyday-events\/zephyr-750-additional-brake-caliper-oh-inspection-shell-engine-oil-change","title":{"rendered":"Zephyr 750 Additional Brake Caliper OH Inspection Shell Engine Oil Change Deco-mainte<\/a>"},"content":{"rendered":"
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The piston got stuck inside, so I’ll do an OH. (I’ll replace the parts)<\/p>\n\n\n\n

<\/p>\n\n\n\n\n\n\n\n

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So here’s the thing…

When doing a full stroke during fluid exchange, I noticed something felt spongy.
Hmm, that’s odd\u2014it feels mushy?

The piston got pushed and never came back.<\/p>\n\n\n\n

<\/p>\n\n\n\n

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When I remove the snap ring and take off the arm, it looks like this.
The piston can’t come back from the other side.

The return spring can’t overcome“corrosion and seizing”<\/strong>that’s happened.<\/p>\n\n\n\n

It’s a good thing this happened during fluid exchange…
If it had happened during a full brake application…<\/strong>that would’ve been scary.<\/p>\n\n\n\n

Bikes are dangerous…I think about it every day.<\/p>\n\n\n\n

<\/p>\n\n\n\n

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The inside of the cylinder is clean. This can be reused.<\/p>\n\n\n\n

<\/p>\n\n\n\n

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The master always has“return ports”<\/strong>.
They’re incredibly tiny\u2014usually 0.5mm or less.
Corrosion or debris can clog them, and dirt buildup can narrow the hole.
Air blowing<\/strong>often can’t remove it, sousing a micro drill<\/strong>to carefully clean from a smaller diameter is more reliable.<\/p>\n\n\n\n

<\/p>\n\n\n\n

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New vs. old comparison.<\/p>\n\n\n\n

You can see the one on the left is quite dirty.
This part got dirty and stuck.<\/p>\n\n\n\n

<\/p>\n\n\n\n

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You can see the difference in the master cup“umbrella opening”<\/strong>between new and old.
As it’s pushed and the cup opens,“hydraulic pressure”<\/strong>is applied, so pressure loss is minimal.<\/p>\n\n\n\n

However, when the cup gets old and“shrinks,”<\/strong>the umbrella opening“develops some lag,”<\/strong>which I think“leads to soft feel and lag.”<\/strong><\/p>\n\n\n\n

<\/p>\n\n\n\n

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Hmm, nowadays the cup isn’t pre-installed…
I just put it in by hand, but…some people might not be able to.( \uff1b\u2200\uff1b)<\/p>\n\n\n\n

<\/p>\n\n\n\n

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And that’s how it turned out beautifully.<\/p>\n\n\n\n

<\/p>\n\n\n\n

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Let’s replace the hose and tank while we’re at it.<\/p>\n\n\n\n

<\/p>\n\n\n\n

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Now let’s finish up the rear caliper.<\/p>\n\n\n\n

Like the front, the rear caliper condition is good.<\/p>\n\n\n\n

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The seals don’t show deformation, but they’ve become quite hard.<\/p>\n\n\n\n

<\/p>\n\n\n\n

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I’ve finished the inside of the caliper like this.

One piston hasn’t arrived yet, so it’s on hold.( \uff9f\u0414\uff9f)<\/p>\n\n\n\n

Parts don’t arrive quickly these days…
I’m used to it, but“it’s difficult”<\/strong>to be honest.

Putting it on hold for now.<\/p>\n","protected":false},"excerpt":{"rendered":"

The piston got stuck inside, so I’ll do an OH. (I’ll replace the parts)<\/p>\n","protected":false},"author":2,"featured_media":21860,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"pochipp_cv_data":"","swell_btn_cv_data":"","footnotes":""},"categories":[1924],"tags":[279,440,122,82],"class_list":["post-21878","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-everyday-events","tag-caliper-oh","tag-shell-oil-change","tag-vehicle-inspection","tag-zephyr-750"],"_links":{"self":[{"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/posts\/21878","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/comments?post=21878"}],"version-history":[{"count":0,"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/posts\/21878\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/media\/21860"}],"wp:attachment":[{"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/media?parent=21878"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/categories?post=21878"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.decoboco.info\/en\/wp-json\/wp\/v2\/tags?post=21878"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}