rhm

I've been trying to get the Gran Sport derailleurs on my 1959 Allegro to work as well as possible. They're not really complicated, and I have no doubt I will eventually figure it all out from first principles. But given that people have been fighting with these things for over fifty years, I know I'm missing out on the wisdom collected by countless mechanics over the years. And I'm frustrated that there doesn't seem to be an online resource that collects it all.

There is, for example, a pretty good guide to the bar end shifters: Campagnolo bar-end levers - servicing and fitting

And there are a lot of pages that help us distinguish the various versions of the Gran Sport derailleur, how to tell a Gran Sport front derailleur from a Valentino one, and so on; but I haven't found a guide to setting up a Gran Sport system.

Is there something obvious I'm missing?

repechage

For the rear mechanism, keep in mind it is 55 years old. I would remove the parallelogram spring and make sure the body moves freely without spring tension, I would even back off the adjuster screws to verify this, feed it oil too.
These bodies usually do not have a lot of unwanted torsional play, but test, don't guess.
I would be tempted to do as I did for my earlier unit, and move the jockey cage to the jockey cage next spring tension port, the aim is to increase the spring tension throughout, makes for snappier shifts.

Otherwise, the same guidance applies, adjust the hangar to insure its perpendicularity to the wheel, (even if using a claw, and especially if using one).

In the road to 10,000… then T-Mar land

sced

Probably the best place on the planet is right here in C&V

rootboy 

I'm not aware of one but…maybe it would help if you stated what trouble you're having, RHM.
GS functions just about like every other Campagnolo parallelogram derailleur.
Any particular snafus?

gaucho777 

Maybe this will be helpful:

https://www.bikequarterly.com/images/...erlyCampGS.pdf

And this, too (though you'll probably want have your browser translate it for you):

https://www1.ocn.ne.jp/~campa/newpage23.htm

rhm

Well, I think I have it working right, but one question is: Are there Gran Sport specific instructions for determining the appropriate chain length? @repechage has already indicated that it may be possible to increase spring tension and thereby chain tension; so that's presumably related.

Another question is: what's the best thing to do with the ball bearings in the jockey wheels? Grease? Oil? Replace with modern plastic jockey wheels? I cleaned the bearings out and packed the balls in grease. It took me a little while to figure out that there are ridges on one side of the jockey cages to register with the flat spot on the jockey cones: overkill, but clever!

As I said, I'm not actually having any trouble now, or at least none that I'm aware of. I had had some trouble, which caused me to change first the front derailleur, then the rear derailleur, to Record models. Still unhappy, I then changed the shifters, and then the bottom bracket spindle. The last two made all the difference; I don't know what was wrong with the bar end shifters, but I like downtube shifters better anyway. And the BB spindle was definitely too long. After I switched in a shorter one, everything fell into place and I was able to get everything working pretty well. So now I switched the Gran Sport derailleurs back in, and I think I have it working right. But: what do I know? I'm not a derailleur guy, and I'm most definitely not a Campy expert.

mapeiboy

Try campyonly.com

repechage

Campagnolo bar end shifters suffer as the cable length is long, and the handlebar to cable stop housing is not longitudinally stiff. Modern index cable housing helps, if you are willing to go that route. I switched from bar ends decades ago as they shifted "vaguely" at best.
Chain length is often made shorter than what one would want as the jockey take up spring just does not have the power any more. That is why I suggested to mechanically increase the tension. When the chain is the "correct" length, when the chain is strung between the smaller cogs and small chainring, chain slap is frequent.
I don't like the "box" front front changer. It is period, but is is slow on the downshift. The nature of the beast I think. An early Record should be superior.