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Thread: Freeing a stuck limit screw

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    Default Freeing a stuck limit screw

    Any advice on a Chorus 11sp FD with a stuck low limit screw? Soak it? Whack it? Heat it? Itís pre-2015 so screwdriver head.

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    Default Re: Freeing a stuck limit screw

    Kroil
    Tim Campen

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    Default Re: Freeing a stuck limit screw

    Quote Originally Posted by nick k View Post
    Any advice on a Chorus 11sp FD with a stuck low limit screw? Soak it? Whack it? Heat it? It’s pre-2015 so screwdriver head.
    It should have a carbon face plate, which I think means that the screws thread into carbon so there is the possibility the screw is cross threaded or seized.

    Back in the day, I'd say just replace the face plate but I don't know that's possible. I think the pivots on pre-2015 were still threaded rather than rivets. If so, I'd remove the pivots and work on the limit screws in the face plate from the back side. I'd try very hard not to remove the threads in the face plate.

    I have a pre-2015 down in the garage but the bear and I have an agreement about visits after 9PM. I'll check in the morning.

    Jorn Ake
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    Default Re: Freeing a stuck limit screw

    Quote Originally Posted by j44ke View Post
    It should have a carbon face plate, which I think means that the screws thread into carbon so there is the possibility the screw is cross threaded or seized.
    I would be veru surprised if the screw threaded into the carbon, that's generally considered not to be good engineering practice. At best the resulting thread will have half the load capacity of the screw, at worst it will promote delamination of the carbon. The usual routine is to bond in a threaded metal insert.

    On the other hand I'm quite certain Campagnolo's engineers know many, many things I don't so maybe they've worked out how to do it.

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    Default Re: Freeing a stuck limit screw

    Quote Originally Posted by Mark Kelly View Post
    I would be veru surprised if the screw threaded into the carbon, that's generally considered not to be good engineering practice. At best the resulting thread will have half the load capacity of the screw, at worst it will promote delamination of the carbon. The usual routine is to bond in a threaded metal insert.

    On the other hand I'm quite certain Campagnolo's engineers know many, many things I don't so maybe they've worked out how to do it.
    That would make sense to me too, but Iíve removed a limit screw once and thought it looked like carbon. That could have just been the area at the edge of the hole though, now that I think about it.

    Either way, getting at the screw from the back would be optimal. Some Campy screw heads are cut for both X and ó tipped screwdrivers, so a nice flat-headed screwdriver might give better leverage for removing a stuck screw.

    Not sure what solvents would work here to help loosen things up.

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    Default Re: Freeing a stuck limit screw

    Quote Originally Posted by j44ke View Post
    It should have a carbon face plate, which I think means that the screws thread into carbon so there is the possibility the screw is cross threaded or seized.

    Back in the day, I'd say just replace the face plate but I don't know that's possible. I think the pivots on pre-2015 were still threaded rather than rivets. If so, I'd remove the pivots and work on the limit screws in the face plate from the back side. I'd try very hard not to remove the threads in the face plate.

    I have a pre-2015 down in the garage but the bear and I have an agreement about visits after 9PM. I'll check in the morning.

    I thought the OP is talking about a FD?

    I would try soaking it in low viscosity lube like a light chain lube and see if it budges.
    Chikashi Miyamoto

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    Default Re: Freeing a stuck limit screw

    Quote Originally Posted by Mark Kelly View Post
    I would be veru surprised if the screw threaded into the carbon, that's generally considered not to be good engineering practice. At best the resulting thread will have half the load capacity of the screw, at worst it will promote delamination of the carbon. The usual routine is to bond in a threaded metal insert.

    On the other hand I'm quite certain Campagnolo's engineers know many, many things I don't so maybe they've worked out how to do it.
    Probably not a good idea to thread directly into the carbon. We've used plastic sleeves in a sandwich construction for a reasonably high load applications and have not had any issues other than the weight penalty.
    Chikashi Miyamoto

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    Default Re: Freeing a stuck limit screw

    Quote Originally Posted by Chik View Post
    I thought the OP is talking about a FD?

    I would try soaking it in low viscosity lube like a light chain lube and see if it budges.
    You're right. I totally missed the FD. What an idiot am I.

    Thanks for correcting.
    Jorn Ake
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    Default Re: Freeing a stuck limit screw

    The Chorus 11 front derailleur does have a removable cage. There are two pivot pins held in place by tiny c-clips. Remove the clips and then you can dislodge the cage, spring and get at the backside of the limit screws to cut a slot and perhaps get them out with a flat head screwdriver.

    Alternatively I've taken to using a very long flat head screwdriver with a nice flat-square tip to adjust front derailleur limit screws. It gets the hands away from the frame which helps get some force on the screw head without destroying it. Also helps on really stuck screws (have not tried this on front derailleurs) to clamp a Vice-Grip to the screwdriver blade to get an top and bottom grip for more leverage.

    But there isn't any carbon I can see on my front derailleur, so I'd soak it in solvent. If it doesn't let loose, try the freezer method for some contraction/expansion effect.

    Again apologies for trashing this thread with my reading comprehension skills.
    Jorn Ake
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    Default Re: Freeing a stuck limit screw

    Since no-one has mentioned it yet: in future you can make your life easier by using a "plus minus" screwdriver in those adjustment screws, reducing the chance of stripping it in the first place.

    https://www.wiha.com/au/en/tools/scr...c-slimfix?c=19

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