Clear instructions for installing rear derailleur mounting or upper pivot bolt

[Patrick Moore]

I bought a Dura Ace 7400 rear derailleur that had an ugly purple aftermarket mounting or upper pivot bolt, and decided to replace it with an original steel one. No trouble getting it apart, but much trouble getting it all back together.

I used to do this myself 10 or 15 years ago, so I know it can be done, but it has been so long that I forget how.

Where can I find instructions for getting it all back together? The problem of course is that you have to keep the little spring pegs or prongs in the holes, one in the derailleur body or "upper knuckle, the other in the little unnamed donut with tabs that the B screw fits into (in the 7400 there is no B screw, just a tab that butts against the hanger stop), then squeeze donut into knuckle while rotating donut backward against strong spring tension so that the non-B-stop tab is held under tension by the tab on the knuckle, then with your fourth hand install the circlip to hold it all together.

Again I've done it, and when I did it, it was hard but not awful, but I have forgotten the skill.

Can anyone give or point to a source for clear instructions?

Another, unrelated question: Is there a way to disassemble the parallelogram plates so that one can file the inner stop? I don't see one with the Dura Ace 7400 series.

Thanks.

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Patrick Moore

Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum

[masmojo]

Well, I "think" I understand what you're asking, but I'm afraid without it sitting right in front of me, it's hard to visualize as I haven't done it in awhile. Looking at the diagram, it appears to go together in much the same fashion as the tension spring of a Shimano Cantilever brake.  It shouldn't really matter, but I would back the tension screw off all the way before reassembly.  if I am seeing it correctly. Insert the spring and spring keepers(?), then rotate the spring until the ends land in the holes at either end. Place the derailleur on a table or use an Allen key to apply pressure to the bolt then continue Turning/compressing the Spring until the groove for the C ring is exposed. With your third hand insert the C clip in the slot. should be easy from there. 

On the other question: the pins that join the Parallelogram plates sometimes have a screw slot (rarely), but because you are asking I assume yours does not. That being the case it's simply a matter of what goes in must come out.  A simple drift to drive out the pin with a hammer. This is chancy though, because once removed it may want to come loose when reinstalled, better to let sleeping dogs lie. is there some chance of getting a Dremel bit in there? If the pin has Knurling to hold it in that would increase your chances of being able to reinstall it satisfactorily.

[Garth]

  Of all places Park tool shows an older DA RD being overhauled with teeny sized photos.

https://www.parktool.com/blog/repair-help/rear-derailleur-overhaul

I've found plenty of videos but they are of the newer style of RD that have an allen head pin rather than the c-clip. I'll link this video anyways of the newer style as he shows and explains well the attaching the spring unit into the body. No music or speed instruction, just him speaking as a normal person.

RJ the bike Guy  https://www.youtube.com/watch?v=L5KWFhzIPoc

[Patrick Moore]

Thank you everyone. It all gives me some thoughts about how to maintain pressure on the mounting bolt while you install the spring and rotate the cage to get proper tension. I'll give it a try.