Crank removal.

[beastie]

I have a chainset that is stuck on to the square taper bottom bracket. Tried a crank removal tool and thought it was working ........ eh no. Stripped the threads on the chains. The other side came off all right. Any suggestions please?

 

[GrumpyGregry]

application of plus gas, undo and drop chainrings out of way and apply Birmingham spanner*?



*percusive maintenance. rubber mallet then increasingly large lumps of metal if it doesn't shift.

 

[Night Train]

You could try heat.
Put the bike somewhere really cold so that the BB axle is nicely chilled, then pour boiling water on the crank arm. The expansion of the aluminium crank might be enough to let it be removed with a soft faced hammer (or a block of wood hit with whatever hammer shaped object you have to hand).


Alternatively, as the crank is scrap anyway, I would use a hack saw and cut the crank off the BB axle. A cut close to one of the flat sides of the square opposite to the crank arm should allow a little force to open up the square in the crank to loosen it.

 

[tyred]

Put the crank bolt back in again but don't tighten it up, leave loose by a few threads. Put the bike in a high gear and mash it going up a steep hill.

 

[beastie]

Put the crank bolt back in again but don't tighten it up, leave loose by a few threads. Put the bike in a high gear and mash it going up a steep hill.

I will try this first, then heat and the "Birmingham
spanner" then the hacksaw.

Thank you loads.

 

[sidevalve]

You could try to "break" the taper with two hammers. One on one side of the crank one one the other. place one hammer on one side and strike the other side of the [same] arm a sharp blow with the other hammer. You need to use good heavy hammers [or one hammer and a good big lump of steel]. May break the crank but either way you've not much to lose.

 

[tyred]

The other option is a ball joint splitter between the inside of the crank and BB cup. I resorted to this on my MTB but just be careful not to damage the frame.

 

[Drago]

You're probably using an Octalink crank extractor on Square Taper cranks. The foot of the pin is fatter on Octalink extractors, it doesn't push through the hole and onto the end of the spindle. Rather the foot catches the edges of the square home and the extractor ends up pushing against itself, usuallycresulting in the threads being pushed out.