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repairing stripped crank bolt options (not pedals)


crazyt
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I have a 155mm bombshell crank which is not easily replaced that had the threads stripped from kids riding it while the crank was loose. It uses a M15x1 as the crank bolt to hold the non drive side arm to the spindle. 

I found an M14x1.5 helicoil repair kit and used that to repair the threads.

 

However now I cant find an M14x1.5 flat bolt of the same style as the original. I have ordered an M14x1.5 drain plug, which is approximately the same thing, but might be too short.

 

The bolt is essentially these

http://www.cyclonebicycle.com/product/32377

 

image.thumb.png.aa847d26d25e54ca6f21a9dddfdfe87e.png

 

I think my options are to find

1) M14x1.5 bolt of the right style. These are the drain plugs

image.thumb.png.7b71f3a869351f5fc136256cbb54f183.png

2) Countersunk M14x1.5 and a countoured washer

image.png.7571d8eb9939e3e7dd9e8678413d7a07.png

3) Find a way to tap the spindle thread. I could only find M14x1.5. Im guessing because the threads on 1.0 are too small for a consumer level kit.

If anyone had access to real machinery that would be ideal..

 

image.thumb.png.d60ba44b402fc056d140c9b9badf6d19.png

Edited by crazyt
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1 hour ago, TheX said:

Long live the tool makers.

100% this. Not everyone wants to populate spreadsheets for a living.

Spent years in and out of those machine shops and learned so much. Watched guys melt down old pistons to fill into cylinder heads that were damaged from dropped valves etc. The guy that taught me used to weld magnesium😎.

Can still smell the naphtha lol.

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The build was a trailcraft maxwell 24. I migrated all the parts over but the spindle threads for the non driveside crank were stripped (hotrock had a 68mm shell and the trailcraft has a 73mm so the original bolt was long enough to hit threads on the hotrock). I used the helicoil to repair the threads which worked great. I wanted to get the lug nut bolt so at least he could ride the bike on his birthday.

I got two versions of drain plugs from amazon (couldnt find the lengths) but shipping was a week out. It turns out both worked. It is one of the few times when every option and backup option worked, which was nice for a change.

Edited by crazyt
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On 11/11/2020 at 7:41 PM, crazyt said:

I ended up finding this from oreilly. It looks ridiculous because it head is too big to fit inside the recess of the crank arm, but it works for now. I am almost 100% sure the drain plugs are long enough based on how well this worked

image.thumb.png.2dad234454d15db5c9f82cfb8c4cc15c.png

could dremel/file that down as needed. Maybe angle grind it down.

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