Monday, April 7, 2008

Seemed like a good idea at the time...

A 9-speed Dura Ace shifter came to me recently with a problem. The release lever wasn't working. It worked if the main brake lever was held in place at the same time the release lever was activated, but that is a very awkward contortion while riding. Usually, this is a symptom of a sticky pawl inside the shifter's guts. An overnight soak in a degreaser can sometimes bring the shifter back to life - especially on older Shimano mountain bike shifter pods.

However, this lever had other things on its mind. I was confident I'd come into the shop the next day and it would be working like a champ. Wrong! Still wasn't working. Hmmm, wonder if Shimano is wrong about the internals not being serviceable. A fifteen minute google search yielded this site on 9-speed STI shifter overhaul. Pretty exhaustive work by the author and very handy.

With this newly found info in hand, I tore into the shifter. Now, it's always pretty easy to take something apart. Putting it back together, on the other hand, well, not always so easy. In the case of the STI shifter, it's a major pain to get the springs to cooperate. I made a tool out of a small screwdriver - basically, cut a slot on the tip of a flat blade screwdriver that I could use to coerce a spring back into it's hole.

The tool's a keeper. The shifter is not. When the shifter was disassembled, I noticed the same problem that was noted on the overhaul site - namely, that the ratchet pawl cage was damaged as shown in this photo (lower right corner).

So, I knocked off the burrs on the damaged section and set about to reassemble the shifter. Hey, maybe by cleaning up the burrs, it'll work. Nope. Got the shifter reassembled and still no go. Next time a non-functioning road STI shifter comes in, "sorry, those aren't serviceable." Lesson learned.

(What's playing: KWMR)

1 comment:

Oli Brooke-White said...

Haha! I am new to your very cool 'site Mike, and this post takes me back to my also failed attempt at repairing an STI lever. The spring struggle goes down as one of THE most frustrating bike repair related things I've ever had the misfortune to deal with! :-D

Cheers for the great reading, Oli from New Zealand