I did a search for Syncro and saw most of the posts were in this forum (as opposed to the mechanics forum), so I'm posting here.

I cannot get my Syncro II left shifter to work. The right one (8 speed) works perfectly. The left one has absolutely no friction and therefore can't keep the front derailleur on the big ring.

I've attached a photo which I hope shows exactly how I'm assembling it. I haven't found an exploded diagram of my exact shifter online, so I'm hoping some of you can help.

The interface between the lever and the brass flat bushing (G) is really friction free. The interface between the "G" bushing and the lever itself is what creates the channel for the cable. There is no channel for the cable milled into the lever itself like in some versions.

I've installed downtube shifters before, most recently a Dura Ace 9 speed where the left shifter has a strong spring to counteract the spring of the front derailleur. I also installed some shifters I got from Velo Orange DiaCompe shifters which (if I recall correctly) used a combination of ratcheting and friction to keep the derailleur on the big ring.

Thanks for any help you can give. I'm hoping it's just a dumb mistake.

The interface of the lever and flat "G" bushing is only friction-free if there is no pressure between the two parts. The contact diameter is large and so should provide much friction at the lever if the adjuster screw tension is being applied to the lever.

Possibly the plastic bush with the square hole is not aligned with the flats on the boss, or is somehow bottoming on the boss at the base of the flats, such that the screw tension stops there and does not force the shift lever against the flat G-bushing.

So determine what exactly that the screw tension is bottoming against, because it isn't the lever and it should be.

Seems like the plastic bushing might need to be moved to the left, relative to part(s) B, C or/and D, which should then produce force on the lever from screw tension.

The parts between the screw and the lever only need to
A) transmit screw tension to the lever, and
B) absolutely prevent the screw from rotating (at all) when the lever is moved.

The plastic bushing along with any washers/parts with internal flats MUST
A) engage the flats on the boss, and
B) float laterally on the flatted end of the boss. Any bottoming at the base of the flats will prevent tension from reaching the lever.

Thanks. That's what I was kind of thinking - that something was preventing the adjustment screw from applying friction. I'll work on that. It seems to me that I recall when I installed those DiaCompe ENE shifters (From Velo Orange) a couple of years ago, I had to put a spacer (i.e. washer) between the frame and part H to push everything out so the adjustment screw could apply enough pressure. It was the same frame, so that might be exactly it, maybe a little idiosyncrasy of this frame's bosses.

In the mean time, on another forum, someone suggested that I had the domed washers (C) aligned improperly. I have them nested so the convex sides both face outward. It was suggested that they should be aligned to create a spring. The person suggested concave-concave, but that made me wonder if it should be that or convex-convex

According to Campy's instructions that shouldn't be the case (and btw, it should be convex sides both face inward):

I've learned a lot from this thread and another one in a different forum: Syncro II Left Shifter Problem

There are two versions of the Syncro II, pre-92 and post-92. I've attached photos of both versions and a diagram of the left shifter.

The pre-92 is as pictured in the diagram parken posted above. It doesn't have the same parts in the same configuration as mine. It has a more centered cable run on the left side. The levers have straight blades.

The later version, which I have, has a cable run on the left that is right on the inside edge of the shifter body, and distinctly, has a cable adjuster on the right side. The levers are curved.

I think 8 speed might be the point they changed (mine are 8)

The above linked thread goes through that and also this web page has a lot of information. The last gasps of Syncro ~ tears for gears

Thanks for all the help. I'm hoping this thread can help future people who are setting up these beautiful shifters. I'm pretty sure my problem is that I have the little concave washers installed incorrectly, and I think I need to add a spacer (i.e. flat washer) between the frame and the shifter brass bushing to push everything outward so that the screw can tighten down better. I think the boss on the frame is a little too long.

To close the thread...

I had to put a very thin spacer (the thinnest appropriate sized washer I had in my box o' washers) between G and H in my parts photo above. The square part of the frame's boss stands proud of part H by a mm or two, and that little bit prevents those two parts from touching, preventing friction. The thin spacer solved the problem and the shifter works perfectly. I might take the Dremel to the boss and grind it down a little, or maybe not.

FWIW: The right / rear shifter is shifting a Campy 8 speed RD (modified with a longer cage for the 50/34 X 11/28 drive train) and a Shimano 8 speed cassette. Although I bought a Shiftmate #1 to adapt the Campy shifting to the Shimano cassette, I forgot to install it. On the stand, it appears to shift very nicely - perfectly to my eyes and ears. I'm going to ride the bike tomorrow and see if that holds true. Just a data point in the big Shimano/Campy world.

Thanks for help and ideas.

My Campy shifter parts stash ahs a few varieties of down tube stops. Older NR/SR shifter boss stops have the square opening indexed differently in relation to the stop in comparision to Synchro levers. The boss stops don't interchange.

But, I also have a selection of thicker stops. I'm curious if these thicker stops are for frames with boss's that 'stand proud'?

The problem is those old shifters kind of sucked. I'd upgrade to a set of vintage Gippiemme...

These ones if you can find them...VeloBase.com - Component: Gipiemme Crono Sprint (retro-friction)

Wise choice, by far the best retrofriction levers ever made (by Simplex btw); I have tried Campy Doppler and SunTour racketing but the Simplex system is simply the best

Now that you mention that, I'll dig through my parts. I have some from some Shimano SIS shifters and another set from my DiaCompe ENE (ratchet type). If any are thicker, I'll use them instead of plan a (spacer) or plan b (modification)