Stripped Pedal Threads

[Electric_Andy]

Hi all,

I'm overhauling a bike for my stepson (child's MTB with 20 inch wheels), and I took the pedals off which were fairly seized but screwed out ok. When I come to screw them back in it seems the threads are knackerd. Rather then welding them back in I was thinking of a Helicoil thread repair - does anyone know what size the internal threads are? FWIW they are smaller than "standard" MTB threads (i.e. tried another set of adult pedals to see if those would go in, but they're bigger). How would one measure - is it simply the width of the internal cavity?

Thanks,

 

[Yellow Saddle]

Remember that the one pedal is a left hand thread. The size is 1/2" but I have no idea what thread it is. BSF or some such.
However, there is a ready-made solution for that made for bicycles. Visit your local bike shop that has a large workshop. They will have the right Cyclus tool. The specific tool is supposed to live here: http://www.cyclus-tools.eu/code720059.html?&L=3 But the page is dead. The tool is great though.
The repair will cost more than a new crank.

 

[Tim Hall]

No, the OP said standard pedals are too big, so they're not 9/16th. Sheldon suggests 1/2 inch x 20 tpi.

 

[PhilDawson8270]

Getting an imperial left hand thread heli coil may be difficult.

A cheap set of chain rings will probably be cheaper too

 

[Electric_Andy]

chain rings will probably be cheaper

Ah, I hadn't thought of that. ok, maybe I will force the pedals back on (it worked on one side, might work on the other), it required a lot of force but nothing snapped. If I ruin anything or it goes loose, I can weld them, and if that all looks too messy I will buy new cranks. Cheers