taguy4

I have a set of old Shimano Sora 9-speed shifters that I used on a bike project I just got done putting together and I'm having trouble getting the right one to index properly. When shifting from high gear (small cog) to low gear (large cog) the shifter doesn't want to move the derailleur enough on each shift to line the derailleur pulleys up with each cog, except for the last shift which all of a sudden brings the derailleur to where it should be. Then shifting the other way (low gear to high gear) it does just the opposite - it moves the derailleur too much with each shift.

I've worked and worked with the cable tension adjustment and the derailleur adjustments, as well as spraying a bunch of WD-40 in the shifter mechanism in case something is gummed up, but I still get the same result. It's as if there is a return spring in the ratcheting mechanism that has lost its tension and so the shifting up and down isn't balanced.

I've read that Shimano 9-speed STI's aren't very reliable and that's why the people who rebuild STI's won't even mess with them, and that STI's in general are not very long lasting compared with non-ratcheting types of shifters. Is this this STI kaput or can it be saved? The left one isn't in the greatest of shape, too, so it's not the end of the world if I have to replace it. These shifters were in a bunch of parts I had been given to from a bike that was salvaged from Hurricane Harvey. Ordinarily I'm not a huge fan of STI shifters - mainly because I think they look ugly as sin - but since they were a gift I thought I'd try to make them work.