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stripped limit screw threads on Ultegra DI2 front derailleur

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stripped limit screw threads on Ultegra DI2 front derailleur

Old 05-18-19, 12:28 PM
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Lotus907efi
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stripped limit screw threads on Ultegra DI2 front derailleur

I managed to just do something real stupid. I have managed to strip the threads out of a Ultegra DI2 11spd front derailleur where the low limit adjustment screw threads in. I have removed the derailleur, unscrewed and removed the screw and looked down into the hole where the screw threads in. It is a metal screw but it looks like the screw threads into plastic. Anyone ever heard of stripping the threads out of a Shimano FD-6870 front derailleur? Is the limit screw indeed threaded into plastic? Any suggestions on how to fix or repair this? Or am I stuck with buying another front derailleur?
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Old 05-18-19, 02:45 PM
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Geekage
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It looks like you might be able to replace the plastic part the screws thread into. edit: sorry, that's mechanical. No similar part in the DI2 parts diagram.


Y5P198010 Stroke Adjust Screws (M4 x 15) & Plate for Band Type

Y5MR98010 Stroke Adjust Screws (M4 x 13) & Plate for Brazed-on Type

Last edited by Geekage; 05-18-19 at 04:17 PM.
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Old 05-18-19, 03:03 PM
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sch
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Looks like the screw is M4 and 8mm long. Next size up is the odd ball M4.5 for which taps are available and
on ebay the machinist world uses M4.5 screws for nominal sums in 8 to 12mm lengths. The normal screw
sequence from M4 is M5, which might be too large. Hard to say as I don't want to do the gyrations necessary
to see what the Low screw actually pushes against. My goto source for odd ball taps is www.victornet.com
but they do have a minimum order. Absent a tap, you order 10 of the 12mm long screws (from China) for
~$10 and carefully grind one to make it into a tap and see how it goes.

For how to do this: https://www.instructables.com/id/Mak...p-from-a-bolt/ or similar on google.
Would require some care with a screw that small but the screws are pretty cheap. Plastic or aluminum
would be easy to thread in this fashion. Or look at self tapping machine screws for ways to 'make a tap
from a screw. They have a short taper then a few scores along the sides to cut threads.

M4 nominal diameter is 0.1574", an 8-32 screw is 0.164", probably not enough larger to work.
Next size is 10-32 at 0.19" which is close to M5 in size, so English screws are +/- as an option.
M4.5 is 0.177" M5 is 0.197"

Last edited by sch; 05-18-19 at 03:26 PM.
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Old 05-18-19, 07:08 PM
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Try a helicoil insert
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Old 05-20-19, 05:42 AM
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Originally Posted by wsteve464 View Post
Try a helicoil insert
Bingo!
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