Replacement Shimano Rear Derailleur Bolt - Mines Stuck

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Replacement Shimano Rear Derailleur Bolt - Mines Stuck

Postby mattwilkinson » Fri Nov 30, 2012 10:37 pm

Hey guys,

I've rounded off 2 Allen keys on my 3 year old rear derailleur. I'm turning it to single speed for now.
Will probably never go back to gears on this, Getting a new bike.

I was wondering how i'm going to get the bolt off. I could use screw extractors, or could I drill straight through it?

If i ever wanted to go back to gears. How do i go about getting a replacement screw?
Do they come with derailleurs as I haven't been able to find anything about this online

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Re: Replacement Shimano Rear Derailleur Bolt - Mines Stuck

Postby WarrenH » Sun Dec 02, 2012 7:20 am

This isn't too difficult. I'm presuming galvanic corrosion with dissimilar metals has caused the lockup rather than buckling from an accident?

Things to get:
Get a new Allen key, of the exact size. Not a cheap rubbish supermarket hardware quality set for $5. Go to a place that sells quality tools, if you were in Canberra, rather than Bendigo, I'd suggest a place like Speciality Fasteners or ring and organize to meet the Snap-on tool van. Does Bendigo have a Snap-on tool van?
Phone a Mate.
A sturdy table or work bench.
WD 40 or a similar type spray.
A light hammer and a glove for the hand that turns the Allen key.
A small bit/s of plywood that will take up the space between the dropout and the stay if the dropout doesn't sit flat on the edge of the table or you don't have a work bench thin enough and you have to resort to using the dinning room table. The plywood will protect the table. If the screw/bolt is protruding you might have to drill a hole in the ply to allow the dropout to sit flat and be well supported.

About an hour before spray the offending part with WD40 or what other anti corrosion spray you might have. Just before you start the removal repeat the spray.
Phone your mate, he will hold the bike on its side parallel to the floor with the dropout sitting flat on the edge of the table.
Put the short side of the Allen key in the screw/bolt and lightly and repeatedly, tap the Allen key (from above the screw) with the hammer while turning it, to undo it. That will break the corrosion bond. It might take some effort. You might even have to tap the long end of the Allen key gently with the hammer, to start to help turn it. But, do start tapping from above firstly.

Don't be impulsive and heavy handed ... this is a softy softly catch a monkey job.

As another thought, when putting the hardware back on, coat the screw thread with an anti corrosion paste like Tefgel or even a Lithium based grease.

Good luck.

"But on steep descending...Larson TT have bad effect on the mind of a rider" - MadRider from Suji, Korea 2001.

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