We spend an awful lot of time on GCN's Maintenance Monday videos trying to
make our bikes look and perform like new. But, let's face it, for a lot of
us, we're also going to be just trying to keep old parts working.
Or maybe even reconditioning and renovation old parts so that they do start
to work. So, with that in mind, here is how to renovate an old rear derailleur and
bring it back from the dead.
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This particular example is a Shimano Dura Ace 7700 rear derailleur from about,
I think, 2002. And it is a thing of beauty. So, when I had to take it off an
old Cyclocross bike of mine because it had stopped working, I was understandably
pretty upset. So, let's see if we can't bring this back to life. The reason that
it has broken, as you can see, partly the jockey wheels are worn out,
but that's easy to replace, and we have a video already on that subject.
But this one is suffering from two frozen pivots. The first one that allows the
whole derailleur to pivot back on your frame. Then the second one,
which allows the jockey wheels to actually tension the frame, has,
you can see, completely seized up.
We'll start very simply by giving it a thorough clean using a soluble degreaser.
Basically, it's just going to make it more pleasant to work on,
if nothing else.
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If either pivot freezes, like with this one, generally it's just a case of taking
it apart and then really thoroughly degreasing them and regreasing them,
because basically they just get so gunked up and slightly corroded.
So, that is what we're going to do now. It is a reasonably complex job.
There are an awful lot of small parts in here, parts that need to be reassembled in
the correct order. So, proceed with a little bit of caution. And remember that
anything you do take apart, just keep a record of the order in which it comes
apart in.
Okay, first up, let's do the top pivot bolt. We need to remove this little
circlip, first of all. There is, as you can probably remember,
quite a powerful spring in here. It is starting to unwind. First thing that comes
off is that, so our B-tension adjustment plate. On the other side of it,
you'll see there's a little hole there. That is the hole that our spring goes
into, So, remember that. Pop that there. Then, we've got a seal,
which has done its job admirably for 14 years. Then, oh, we've got a spring.
There we go. It's as simple as that in there.
Right, the second one is a little bit more complex perhaps. And to start with we're
going to need to take off the jockey wheels so that we can actually get access
to that bolt there.
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To remove this lower pivot then, we need a 5 mil Allen key, and we just need to
unscrew. At this point, you really, really need to be careful,
because the derailleur cage will start to unwind, and we need to remember which way
it unwinds so that then when it comes to putting the tension back in,
we do it the right way. There it goes. I don't have any biceps.
Right, come on then. Ready, there we go. Oh man, look at that.
Yeah, that's probably why it wasn't moving very well. Can you see that?
Can you see that?
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Okay, we are as clean as we're going to get. And you can see actually now,
if you look closely, there is quite a bit of corrosion on the bushing there.
So, we maybe need just to take the very edge of that off with a tiny bit of emery
paper. But hopefully, hopefully, just a thorough regrease is going to get it back
so it is at least functioning again. Keep your fingers crossed.
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Aha! How satisfying is that? Now remember, as we're tightening that screw,
we also need to move the lower cage of the rear derailleur so that it's in its normal
place. If you remember, there was that stopper screw just on the back,
so that needs to clear the derailleur cage. And then as we tighten the screw,
it holds it in place. So, that is now back working. There we go,
sneak preview. Look at that. I'm feeling good about this repair.
Let's do the top pivot now. So, that is all thoroughly cleaned.
Push the pivot bolt back in, then our spring. You can see the hole inside there,
that's what we need to locate. If you look at that spring, you'll see that it's
not actually symmetrical. One little prong is longer than the other.
So, the longer prong goes inside the actual body of the derailleur itself.
More grease.
There.
Okay.
This last bit is going to be the trickiest bit. We have to put our B-tension
adjustment plate back over the spring, so we line it up. And then we have to twist
it counter-clockwise to load the spring whilst pushing it in, holding it in place,
and then grabbing our circlip and pushing it back into place so that it all locks.
Come on, do it. Quick! Quick!
I'm in!
Just got to put our jockey wheels and cage back together now. I did say this rear
derailleur needs new jockey wheels, but, for the sake of this,
these old ones will at least function. Ready for the moment of truth?
Look at that. It works. It works. One successful renovation of a
Shimano 7700 rear derailleur. It's back in action. That's the method for a
Shimano Dura Ace 7700 rear derailleur. Most Shimano rear derailleurs are going
to be very similar to this. Most Campagnolo rear derailleurs will also
be quite similar to this. But SRAM, SRAM is slightly different.
So, that top pivot there, that doesn't have a spring in it. So, it won't ever
freeze, but you will occasionally,
perhaps, need to lubricate it. And then, that lower pivot there,
that cannot be serviced. So, do not try disassembling that because you will come
rapidly unstuck.
Well, that hasn't really taken all that long actually to bring back what is
rapidly becoming a piece of history to life. In fact, it's taken considerably
less than an hour. So, you don't even need all that much spare time.
Just remember that when you do sit down to do a job like this,
you've got a good place to do it so that you're not going to be losing any tiny
little fiddly bits in thick carpet or, I don't know, underneath your fridge or
something like that. And then, also, every time that you take something apart,
you keep a track of exactly how it came apart, and the orientation of the parts as
well, because like I mentioned with that spring, that is really key. There we go.
Now, for more maintenance videos here on GCN, we have an
absolute ton. Why not subscribe to the channel? That way, every time a new
one comes out, you will know about it. To do that, just click on the globe. Now,
it will not escape your notice that those jockey wheels really do need repairing
before I press this derailleur into action. So, to know how to replace jockey
wheels, although you probably already do. So you can click just up there.
And then, the other key thing is to index your rear derailleur perfectly,
and we've got a really in-depth look at exactly that just over there.
Oh, and if you do like reconditioning and renovating old parts, give this video
a thumbs up, and we'll do more.