oldnslo

I've narrowed down the "wont make the 3rd shift" assessment to a level, that I would like someone who has disassembled already to help guide the conversation. As background primer, its not sticky lube, or wear. This is a ultra low mile bike and shifter. I'm operating the brifter without any cables/housing.

The Shimano exploded view does not reveal the guts, which is what I need. In a nutshell, there are 3 components in play. The lever, the sprocket wheel and the catch pawl. In this case the pawl does not clear the 3rd sprocket position, and thus just engages the two positions. I can manually get the 3 position to actuate, so it is working in that aspect.

What I surmise is that there is some "stop" or adjustment that ends the arc of the lever during a shift? If I could somehow adjust that arc a smidge, it would allow the pawl to clear the sprocket tooth, and joy would once again reign supreme. The pawl is free and not an issue. As a final data point, a YT vid on a Shim 105 triple shows that there is 2 sets of ratchets on the sprocket wheel, one top, and one bottom. If that's the case on a Sora, I cant view the bottom unless I fully disassemble.

Got any insight into adjusting that "arc", or another way of advancing the sprocket wheel a smidge?

Kontact

Which Sora shifter do you want help with?

masi61

Did something change about your Sora triple front shifter? Like maybe you just replaced the cables and housing and now you are setting up the cabling?

Did it previously shift well and now it won’t shift to the biggest chainring (what you call 3rd position).

Also. If the front shifter isn’t consistently shifting, the normal maintenance of cleaning out the mechanism with PB Blaster or WD-40 might loosen up any hardened grease that might be in there.

oldnslo

Kontact , its a ST-3304, thanks. (edited)

70sSanO

I am assuming you have an ST3303 and not an ST3300. From what I have read, (see thread below), the ST-3303 (triple), does not have a trim function, but the ST3300 (double) does.

If you are getting the clicks you want but not the travel, and it is an ST-3300, it is not a triple shifter.

There is also an ST-3304, which is a triple and has trim.

Here is a thread that goes through this...
https://www.bikeforums.net/bicycle-m...3-no-trim.html

John

oldnslo

I've edited the earlier post to be ST-3304 and is clearly marked. I was looking at the RD side when gathering the number. It has the trim function, however I was ignoring that callout in the 3rd shift description as the 3rd selection is available via a manual (not lever) intervention, and is not the trim function.

As mentioned earlier, it WANTS to get into that 3rd position, but just wont make it over the tooth to the 3rd position, unless manually operated.

Kontact

Just curious, have you actually tried this with a cable? And have you checked that there aren't any cable fragments jammed in the mech where Shimano shifters tend to break them?

oldnslo

Diagnosed originally with a cable and housing, then removed those to eliminate those as causes. No cable breakage, fragments, not crashed, no road rash or damage. All parts are visibly in working order because the cover has been removed, and can be manually operated in all 3 positions, just not with the lever for the 3rd position.

Kontact

What is manual operation vs lever operation?

oldnslo

Referencing back to the OP, a small screwdriver can be used to manipulate the sprocket past the pawl without use of the shift lever itself. This manual operation with a screwdriver ensures all shift positions (in this case 3 plus a trim) are available to use. In other words, there is no binding in the critical parts involved with upshifts or downshifts. It's only the shift lever that does not have enough travel (seemingly) to over center the pawl past the 3rd sprocket position.

Kontact

Later hidden cable shifters were more prone to this, but I would be looking at where the lever contact the internal mechanism. Shimano shifters generally work by moving both levers simultaneously for shifts to larger cogs, and uses the small lever to lift the pawl up so the large lever can rotate the internal cog unimpeded. If the internal lever from the small lever gets bent or worn, this 1, 2 timing gets off and effectively blocks the cog from being moved.

I dunno if that is the problem with your shifter, but it would explain what you are describing.

oldnslo

Kontact , it appears a partial disassembly is in my future in order to get a bottom view of the sprocket, where the lever engages the mechanism to advance the gearing. Your response confirms what I suspected in the OP of there being two pawls (I've used pawl and ratchet interchangeably), as observed in a YT vid.

Thanks for your responses.

icemilkcoffee 

Unless the brifter is brand new, typically they need some tension pulling on them to work properly. You need to insert a cable in there, and constantly pull on that cable while shifting

oldnslo

Thanks, however that's not been my experience with these, and is definitely not the case for this specific shifter.

oldnslo

Case closed, issue resolved.

Root cause = 2nd pawl (lower and hidden from view), was not fully pivoting, where the upper (and viewable) was free to fully pivot.

Solution used = While lube was initially used, and a heat gun for warming dried grease, the placement of the brifter FACE DOWN overnight, allowing a further migration of lubricant along with an additional heat gun cycle (warm to the touch, not hot) freed the pawl from its unwelcomed hold on the pawl shaft.

Thanks all for their responses.