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Rethreading crank arm
#1
Morning all

I've managed to strip the thread of the pedal insert on a set of M770 crsnks (left arm fwiw).

Does anyone know if this can be helicoiled and if so where would a good place to use?

Thanks all
Ride the Spiral to the end
It takes us to where no ones been
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#2
"stayhigh65" Wrote:Morning all

I've managed to strip the thread of the pedal insert on a set of M770 crsnks (left arm fwiw).

Does anyone know if this can be helicoiled and if so where would a good place to use?

Thanks all

Yep they can be heli coilled. Theres a place on the Medway city Estate which do them but cant remember what their name is...a light engineering firm..I'll put my thinking cap on
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#3
Do you know what thread it is and I will see if we have the correct helicoil at work on friday.
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#4
LH pedal thread is the LH threaded one (I think Undecided)
Make sure your enquiries for helicoils reflect that - it may make it much harder to find.
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#5
"Jon" Wrote:Do you know what thread it is and I will see if we have the correct helicoil at work on friday.

[Luditemode]Do you mean the size of the thread?[Luditemode] a quick google says axle thread is 9/16" if that sounds about right?

If you like I can drop the offending part round to you tomorrow evening on my way to work.
Ride the Spiral to the end
It takes us to where no ones been
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#6
Dont worry about dropping it round. I have an old crank arm I can use to check. If it is imperial or left hand thread I probably wont have the correct one though. I will see what I've got when I'm back in work on Friday and let you know.
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#7
Sorry to be the bearer of bad news, but......

I'm pretty sure it'll be a 9/16" 20 tpi thread & I'm very sure it's a LH thread Sad

A set of taps (that's a tool for recutting threads, not something water falls out of Wink) will cost you about £30; if it can be saved.

A helicoil should be less to buy, but they can be tricky to get right without the right equipment/knowledge.

I think the M770 is Hollotech II Undecided  That means the crank arm is hollow & helicoiling it may not be the best idea anyway.

I'm happy to have a look as always, to see if it can be saved, but also think about asking Medway Cycle Repair or loking for  SH crank or crank arm.
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#8
If it'll cost 30 odd quid for a set of taps to fix then definitely better off looking for a 2nd hand chainset, i've seen M770's go for about 20 quid.
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#9
Definitely a left hand thread.  I only have the tools to do right hand threads so I'm out.  I am fairly sure you can buy a left hand crank arm for jejames.com.
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#10
I've got taps somewhere.
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