Any suggestions to undo 987.2 clutch hard line union?

See pics. This is a design revision from the threaded union on the 986 and 987.1 , and I haven't found any references yet for how to get it apart. In my case, the line failed at the crimped connection between the hard line and the rubber "U-turn" hose. The replacement part number is 987-423-113-16 and I've confirmed that it is correct for my vehicle. As situated in the car. This is under the left (US driver's side) side of the car, pretty much under driver's door latch. I removed the rearmost and the left-rear underbody trays to see this. The front of the car is to the right in this picture. A zoomed in version showing some more detail. Note how the rubber is folded up. I can easily push the left (male) part of the union deeper into the right (female) part, so they're not binding at all that I can tell The forward side of the union on the replacement part. You can see that there's an O-ring seal with a backup, and then there's a C-clip which I imagine is what retains the two parts together. The aft side of the union. Note that the flat metal ring and the rubber cylinder are a separate "collar" part, and can slide towards and away from the C-clip. So far, I tried just pulling the halves apart, and using a screwdriver and a dead-blow to hammer the body of the union towards the left, to no avail. After some thought, my current guess is that this might be like a fuel line fitting with an integral release tool, where the sliding collar can push forward to disengage the C-clip. Will see if I can persuade it forward when I get back under the car in the morning. That said, if anyone's done this before or has suggestions or advice, I'm all ears.

No judgement, my first advise is do not hammer it or use similar force, you could damage it. Given that it shows no corrosion, it should separate correctly without undue force once someone weighs in on the proper procedures. Good luck, hopefully someone here can provide the correct answer. Till then if it’s in a safe place where it’s not in your way? Take a break from it. It might compress to release, wild guess.

On BMW ’s there are quick release fitting where you first have to push the male part in, then pull on the release ring to separate the two. wonder if this is similar to that?

There's a special tool for it. I purchased one when I changed my power steering hose. Release 000-721-978-00 | Gaudin Porsche Parts is the cheapest I've found. Other sources go for around $70. Edit: removed redundant image

Here's more info. Edit: Didn't realize Google Drive links embeds the document where you can hover over the image and scroll with your mouse wheel or scroll normally on mobile. Cool!

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Reminds me of a Shark Bite fitting for plumbing, and the tool seems like it works similarly.

Thanks for all the suggestions and references, y'all. This was actually super easy to release. A screwdriver or two would probably do the trick, but it turns out the Harbor Freight metal trim tool was even easier (Harbor Freight #99739). I just pushed the collar forward with the trim tool until I saw the orange O-ring (and worked it around the circumference a bit to make sure it wasn't slanted), and then I pulled the union apart. Installation is just to push the two pieces together until they click, and to make sure you can't pull them apart again. There will be some float in the union when it's properly connected. The black colored cap from the Dorman #47397 vacuum cap kit fits perfectly to plug the upstream side of the union. I inserted it with the open end facing out, and then I was able to use a pick (or screwdriver) to fish it back out. Pro tip, that same cap size fits over the slave-cylinder end of the hose, so you can keep it clean while fishing everything through the undercarriage (as delivered, the union side includes a cap but this end is open) Here are the old and new parts side by side. They are actually a slightly different shape, and I ended up needing to tweak the new one a bit to get it to lie correctly. Thankfully, as long as you follow the right trajectory, it's actually easier to get the new one in and situated than it is to get the old one out After everything's situated, things line up exactly where they need to be. Already went for a test drive and everything's working as it should.

Nice find! Glad things worked out.