[sanjuro]

I have an old Raceface Northshore crankarm which took a biff and stripped its pedal threads. The pedal was still attached but coming out at an angle.

I can probably retap it, but has the arm been signficantly weakened? Has anyone retapped a crank pedal thread before and continue riding on it?

 

[mr.loops]

I have an old Raceface Northshore crankarm which took a biff and stripped its pedal threads. The pedal was still attached but coming out at an angle.

I can probably retap it, but has the arm been signficantly weakened? Has anyone retapped a crank pedal thread before and continue riding on it?

Try to retap the pedal first. If the threads are really gummed up you might not be able use the crankarm (pedal might fall out due to no thread engagement)
If this is the case, you can always heli coil the crankarm. Use red loctite, allow it to cure before riding and you should be fine. (I have done about 20 pedal heli coils and have yet to see one come back failed)
Good Luck

 

[ultraNoob]

I agree with Mr. Loops. I've been a mechanic for 15 years and the only real tricky part to rethreading/heli-coil is drilling it STRAIGHT the first time cuz there's no do-overs.

 

[sanjuro]

Well, the boss gave me a great tip: do it from the inside of the crank arm, where the good threads are...

 

[ultraNoob]

To do a proper heli-coil job, you need to drill out the old threads, tap it with the designated heli-coil tap, then follow it with the thread insert all the way through, and finally snap off the install tab.

 

[oiswego]

this is exactly what i need to do!
http://www.ridemonkey.com/forums/showthread.php?p=2553587#post2553587

since helicoils are a new idea to me and you guys have done it before....
what size helicoil do i need?
what size drill bit?

any other advice before i try this out tonight?

 

[ultraNoob]

From my understanding, there are 2 thread sizes for pedals and you'll need 2 heli-coil kits. One pedal is left threaded and the other is right threaded. Each heli-coil kit runs about $40 + the drill bit. The right hand thread is easy to locate, but the left hand thread may be a special order at your LBS or autoparts store.

Off the top of my head, not really sure which side is left threaded or right threaded.... but right threaded is "righty tighty, lefty loosey"

Unless you're doing lot's of rethreading or work in a machine shop/repair shop, I don't really think it's cost effective to DIY. Your LBS might do it for the cost of buying 1 heli-coil kit.

 

[chinkerjuarez]

Right Crank arm, drive side, is Right hand Threaded. Left Crank arm is left hand Threaded