Classic & Vintage - Campy NR FD stuck pivot - how to loosen?

I received a nice Campy NR FD, and noticed that the cage was really hard to move. I thought the pivots were gummed up and just needed a good oiling (as has been the case on several old RD's that I've had). However, working in light oil into the pivots didn't loosen them up.

Two out of three pivots can be disassembled: the one which holds the return spring unscrews from the cage, and the other pivot on the derailleur body slides off after removing a circlip. Upon inspection, those two pivots are just fine, not at all gummed up. The non-serviceable pivot point below, which connects the pivot arm to the cage by means of a rivet, was found to be the culprit:

http://farm8.staticflickr.com/7141/6610205985_d492265b25_b.jpg

This pivot takes a lot of force to move, so much so that it counters the return spring's action to the point where the RD can't reliably return to rest by spring action alone (the spring seems very strong). No amount of oiling has loosened it up. It feels like it's binding. What's causing it and how can I remedy it?

Clamp the round end in a vise with soft jaws then work the cage back and forth a bit to open the ears. This pivot can be pretty snug and still work well. That's a pretty heavy spring. You can also try hammering a blade down between the arm and the ear to make a little gap. But you do want to use anything too thick.

Clamp the round end in a vise with soft jaws then work the cage back and forth a bit to open the ears.

Ah, I didn't follow until I re-read this a few times... I see now. Basically you're suggesting yanking at the arm perpendicular to the pivot plane of movement. Should I worry about snapping the pivot arm?

Ah, I didn't follow until I re-read this a few times... I see now. Basically you're suggesting yanking at the arm perpendicular to the pivot plane of movement. Should I worry about snapping the pivot arm?

If you snap it, you have proved to yourself that you are not meant to be a mechanic :)

Okay, I tried it. No go. I could see that I was flexing the arm (without even excessive force-- scary!), while the cage ears were immobilized in the vise, and after applying force enough to flex the arm slightly about a dozen times, the pivot is no looser than before. Time for your plan B. I wonder if a razor blade will work?

Expanding the distance between the steel tabs of the cage is the plan.
A razor blade is sharp of course, and a bit brittle. Safety glasses time.
I can think of a bunch of ways to attack this, but your tool access is going to guide you.

Expanding the distance between the steel tabs of the cage is the plan.
A razor blade is sharp of course, and a bit brittle. Safety glasses time.
I can think of a bunch of ways to attack this, but your tool access is going to guide you.

I used a razor, and it worked... sorta. The razor's edge was thin enough to wedge between the arm and the steel ears, using a light tap of a hammer to drive it in the couple of mm before it reached the pin. I was also able to tap the razor causing it to rotate around the ear as it was wedged in. After doing this on both sides a few times, the arm is a LITTLE bit looser, but not loose enough to where I'm comfortable reassembling it. I might work in some heavier oil and repeat with a fresh razor, and call it done. Anything wider than a razor's edge is too wide to try to wedge in there.

What were some of your ideas, repechage?

What were some of your ideas, repechage?

I would fill the cage with a hardwood scrap section- a lucky cut off or sliced to fill tight, install the copper soft jaws in the bench vise, some more blocks to clear the inner tabs and that would stabilize the cage. From there a single edge razor blade might just be enough on each side at the same time, razor blades come in two thicknesses and the cage ears will spring back. You might have to wedge in from the sides, not just the top.

Working the arm possibly during and after should help too. This is the one Campagnolo part that often came as an assembly as you have.

Or, if you're feeling very ambitious, or seriously bored, you could grind off the head of the rivet/pin that holds the assembly together and start anew after widening the gap a hair. A bit extreme perhaps, and I probably wouldn't suggest this if that wasn't an early flat cage. I just happen to have one OEM replacement pin and several of the bronze bushings, Southpaw, if you want to attempt it.
That said, I think if it were me I'd try Repechage's method first.

Again, these can be pretty snug and still work fine as the return spring is heavy (and better a bit snug then sloppy), also the travel is not that far, so as long as it moves freely in the range of travel you should be fine.

I would at least assemble it and see how it feels. If still too tight, I would drive the pin out and re-assemble. You usually only have to file the exposed edges of one side of the pin (pick the side that looks "less swedged". I back up the ear with a small deep socket and knock the pin through with a steel drift and hammer. The trick is not to knock the pin all the way out, just let clear the pivot arm but leave it in the ear.

Now, I take a file and flatten the head of the pin against the inner ear making sure there is no burr left. Clean everything (there's a small brass bushing in the pivot arm), grease and re-assemble. To do this I use the socket to back up the other end and squeezr the pin back in using a vise. It's a good idea to make a fork shaped shim or use a .005 feeler gauge to stick in between the pivot arm and the ear to hold a gap while squeezing it together. This will keep the ears from getting too tight against the pivot.

Once the pin is back through you just have to lightly peen it over, and you should be good to go. I've done this enough times that I can do it with two hands, but it really helps if you can have somebody help out, as it's a bit of a juggling act to hold everything in position.

Use the hotwrench to get everything fairly hot-- like a damp finger will sizzle on it-- and squirt some PB Blaster in there. As the metal cools, capillarity will draw the penetrating oil in further. Do this outside, or in a well-ventilated area, though, as the fumes are truly gnarly.

Okay, update: I used the razor again as mentioned before, repeatedly inserting the sharp edge between the arm and the cage ears by tapping with a hammer, and then let some medium weight oil wick in. After repeated nudging, the pivot became looser. This afternoon I checked again after the oil had worked in, and it had loosened up even more, to the point of being almost no resistance-- but still snug. I'm guessing the original stiffness was due to a combination of tight compression and gumming up. I put it all back together and it works great! Smooth, with a strong return. Installed on bike and works as predicted. Not quite as nice as the Huret Jubilee which it is replacing, but fine enough.

Thanks all for the fine advice!

Put a drop of light oil in the seams once in a while to maintain the smoothness. Good job!