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I want to disassemble my Rear Derailleur 9-speed -> https://bike.shimano.com/en-EU/product/component/acera-m3000/RD-M3000.html

Here is a video of instructions for disassembling a general rear derailleur:

I've removed the upper G-pulley, but I want to remove the metal part, but I don't see how, did not find videos, the manuals did not mention that part. But there is a little cap at the bottom, it's difficult to remove it and I wonder If it's a real cap, it there a screw behind it ?

On the picture below I want to remove the metal black part below. Need help.

enter image description here

The image of the "cap", can I remove this?
enter image description here

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  • Currently I'm trying with a thin Swiss knife to remove the cap, but it's not east. The cap is getting destroyed.
    – mihkov
    Jun 24 at 21:35
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    Even this scheme doesn't show the part can be separated: dassets.shimano.com/content/dam/global/cg1SHICCycling/final/ev/…
    – mihkov
    Jun 24 at 21:44
  • Do you mean a cap around the center of a jockey wheel? Or some other cap? Arrow is not pointing at a jockey wheel, so does this derailleur have something else at that "elbow" ?
    – Criggie
    Jun 24 at 22:13
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    @Criggie I've added another photo with the "cap" or cover (not sure what is the correct word for that) check the post, I'm talking about this "cap" and whether there is a screw behind it. You can see the scratches already I've made with the knife. So I wonder, can I remove this?
    – mihkov
    Jun 25 at 6:22
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Many Shimano derailleurs do not have any removable hardware to disassemble the cage pivot area as shown in that video. I believe what most of those that don't have instead is a peened retaining pin that occupies the same place and does the same thing. If you wanted to explore the notion of hacking it into something that is removable, it would probably be a good idea to start with a discarded derailleur with a similar pivot design that's already toast. It's probably not worth it from any kind of functional repair/maintenance perspective.

Basically the only time it's worth worrying about servicing the cage pivot on a non-clutch RD is when someone has immersed the whole thing inappropriately in solvent. Barring that, the pattern is that one goes to all the trouble of getting into it, the grease is still in there doing great, and dealing with getting the spring wound into place is a giant waste of time.

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  • thanks for answering, I don't have spare rear derailleur and that's why am asking to not make it worse. I'm worrying because it have some struggle noise when it's moving, I just want to clean and put some grease again if it's possible.
    – mihkov
    Jun 25 at 6:27
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    Getting the spring back is a real PITA.
    – Vladimir F
    Jun 25 at 6:56
  • Actually I didn't went to that part in the video 16:00, it looks easy when you have proper tools, but in my case it might be difficult. It's a good reasons to delay this maintenance. for that part of the derailleur
    – mihkov
    Jun 25 at 8:03
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    Concur - thats a spring under tension in there. They do not play nice when reassembling - I've never achieved it. Buying a new derailleur is a better idea
    – Criggie
    Jun 25 at 8:47
  • I have plans in the future for buying a new derailleur (upgrade for bigger cassette), maybe winter and there will be a good time to disassemble current derailleur .
    – mihkov
    Jun 25 at 10:11
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I concur with Nathan's answer. It's typically not cost effective nor of much benefit to take the cage off of a rear derailleur at this (relatively low) level of Shimano hierarchy. New Acera derailleurs can be purchased for the mid $20USD range. If your time means anything to you and the fact of questionable benefit makes tearing into this a possible waste of time.

That said, (-: the piece you are trying to remove is a U shaped clip which retains the derailleur body to the bolt that is fixed to the inner cage plate. It does come out with some good persuasion. Inside this area is a spring, one end of which you'll see set into the inner cage plate behind the pulley wheel. Remove the outer cage plate by removing the pulley bolts. When the outer facing aspect of the inner cage is accessible, it might help to push the end of the P-spring into the derailleur body which will free the cage to turn. IIRC you still need to remove that retaining clip in order to remove the inner cage.

Inside you'll find just the P spring which is directional so keep track of the orientation. The spring surrounds a hollow axle of thin metal. The spring's ends set into little holes--one in the derailleur body and one or two in the cage. During reassembly you'll set the ends of the spring into their respective holes and wind the cage to generate the P-spring tension. It's a bit tricky to keep the ends of the spring engaged while keeping the cage out a bit from the derailleur body so that it can spin beyond the body's cage stopper. In the video, the stopper bolt can be removed, but at this level the derailleur body has a raised section molded into it or the stopper is a fixed pin that cannot be removed from the cage. So the technique is to wind the cage generating spring tension then when beyond the stopper bolt, push the cage and derailleur body together and reinsert the u clip.

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One of the Shimano official facebook pages answered me, that this model of derailleur cannot be dissembled as I want. They've send me the same scheme I posted somewhere above (just the link is different): https://si.shimano.com/api/publish/storage/pdf/en/ev/RD-M3000/EV-RD-M3000-3841B.pdf

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