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Stuck Sora lever

thistle_thistle_ Posts: 5,692
edited February 2011 in Workshop
I was riding in today, went to downshift to overtake the car in front and the lever wouldn't budge, so I just had to keep up with him.

I got to work and had a quick look at it.
Pulling the exposed bits of cable makes the deraulleur shift over, so it's not the derailleur.
I unhooked part of the outer and pushed the cable into the shifter so it poked through the other side and the lever would move again an click. I put the cable back in and it jammed again.
The cable is only 2 weeks old - not frayed and slides through the outer nicely.

Anyone got any idea what the problem might be and how to fix it? There's a massive hill on the way back home and I'd appreciate not having to go up it on the 11T :(

Posts

  • Mike67Mike67 Posts: 585
    Is the nurdle (not sure what it's called) on the end of the cable seated properly in its hole in the shifter? It should go right in and be flush with the innards.
    Sounds like the shifter is functioning but something is stopping it moving around with the cable in place..

    Also check the nurdle is the correct size/finished correctly. I've had ones that have residual bits on them that I filed off before fitting.
    Mike B

    Cannondale CAAD9
    Kinesis Pro 5 cross bike
    Lots of bits
  • Buckled_RimsBuckled_Rims Posts: 1,648
    Cable stretch as it's only 2 weeks old.

    Click the shifter to the 11T cog. If it's cable stretch the cable will be all floppy under the chain stays, it should be like a bass string on a bass guitar. If that's the case, just loosen the RD cable clamp, pull the cable tight and tighten.

    Turn the bike upside down to test as the indexing might need a few quarter turns.
    CAAD9
    Kona Jake the Snake
    Merlin Malt 4
  • thistle_thistle_ Posts: 5,692
    Cheers for the replies so far.

    Buckled_Rims- I don't think it's cable stretch. There was hardly any slack in the cable when it was on the 11T. I had to push the dérailleur over by hand to give enough slack to pull the cable out of the frame.

    Mike - I think the bit on the end of the cab;e was seated properly. It worked fine for 11 miles then half a mile from work it just jammed. I'll try poking it to see if I can get it in any further, but I think it is seated correctly.
  • deswellerdesweller Posts: 5,175
    Had the old cable frayed at all? You might have some leftover strands in the shifter.
    - - - - - - - - - -
    On Strava.{/url}
  • thistle_thistle_ Posts: 5,692
    Des - not sure about a fragment of frayed cable. It's a possibility although it seems to be something more solid.

    I have blasted it with GT85 and it seems to be a bit better - it ratchets most of the time, but much more reliable when you are pulling the lever (as if you are braking) so I think it's catching on something. Leaving it to dry off a bit before regreasing and testing it.

    Thanks for the suggestions :oops: :D
  • thistle_thistle_ Posts: 5,692
    On the off chance someone else has the same problem, here's how I managed to bodge it back to working order.

    I tried blasting it with GT85 and it all seemed to work until I put some grease on the moving parts, then it all jammed up again. There didn't seem to be any loose fragments of cable or expired mechanism jamming anything either.

    Pull the lever back to expose the top, remove the 3 screws (keep them very safe) and undo the 8mm bolt on the front of the lever (don't worry, it won't all spring off). Pull the plastic covers off the top and off the front to expose the innards.
    I'd already taken the gear cable out to do this (and the bar tape off - mistake) but I'm pretty sure you can do it with the cable still in, it just makes getting on of the plastic covers on and off more difficult.
    Strap your lever up against the bars to make it easier:
    ugw7_450_u945o.jpg(Click image for bigger version)

    This is what it is supposed to look like inside (photo is the left lever):
    ugw7_723_u945o.jpg
    This is the right (jamming) lever:
    ugw7_89c_u945o.jpg
    For anyone who can't be bothered clicking for the bigger pictures or is otherwise censored at spot the difference, there is a spring on top of the ratchet pawl which hooks onto a sticking out part of the metal body of the lever mechanism.
    On the right lever, this sticking out part has sheared off so the spring is not attached at one end and the ratchet doesn't work.

    It's the bit by the pliers where it broke off from:
    ugw7_4a0_u945o.jpg

    Part 1 of the bodge - grab the straight end of the spring (the one on the inside of the lever) and bend it around 90 degrees as close as you can to the coil:
    ugw7_33c_u945o.jpg(you probably will need to click this to see the detail)

    Next, make a groove in the metal plate at the front of the mechanism. This should be just wide enough for the spring to fit in and just deep enough so it doesn't stick up too much above the top of the plate. I tried doing it with a hacksaw but it wouldn't dig in so ended up using a needle file:
    ugw7_433_u945o.jpg
    A grinding attachment on a Dremel would probably do the job, but be gentle with it and try not to grind any other parts of the mechanism - it's very congested and fiddly in there:

    Then all you need to do it to get the spring back into place, which is incredibly fiddly. One end sits on top of the ratchet pawl, the other needs to hook into the groove you just made. I used some snipe nose pliers to put the pawl end on first:
    ugw7_7f3_u945o.jpg
    Then I used the pliers to grab the other and stretch it into place:
    ugw7_ac2_u945o.jpg

    It will stretch the spring slightly, and it will be a bit wonky but it is working OK for me. The closer you can bend the spring to the coil, the more spare length you'll have to get it into the groove. If you've got the groove the right size, it should fit in nicely:
    ugw7_979_u945o.jpg

    Then all you have to do is put all the bits of plastic back on, put the nut on and the screws back in, put your gear cable back in if you've taken it out and job done :D

    I'll post back whinging when it breaks. I've done 45 miles this morning though and it's lasted that far which isn't bad.
  • I'm not sure if you've seen this before but here's an instruction how to repair Sora. But Shimano documentation might just be as good if you need to take everything apart :shock:

    http://www.instructables.com/id/Servicing-repairing-Shimano-Sora-Shifters/
    CAAD9
    Kona Jake the Snake
    Merlin Malt 4
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