Originally Posted by LarDasse74

THere are a couple reasons I can think of that the threads pulled out -

The first one that comes to mind is that there was a washer sitting in the place that used to be under the bolt. Without removing this washer, the puller is pushing agains the washer, which is fixed at the base of the threads, and pulling aginst the threads... since there is nowhere for the washer to go, the threads let go. This problem is usually identified by the mechanic pushing with all his might to turn the puller, but it seems that the crank is seized... the mech pushes and pushes until he feels the crank start to move, except it isnt the crank moving, it is the threads letting go.

Another possibility is that you failed to thread the puller all the way to the base of the threads - if too few threads of the crank are engaged with the threads of the puller, it is possible to pull the engaged threads out without an extrordinary force.

Lastly, the crank could be seized to the spindle. This is possible, but from my experience, less common than the forst two problems.

Of course, you will need to have the threads re-tapped to a larger size - there is not enough material left to cut threads at the original size. Many crank pullers used to have two sizes of threads (reversible). THe smaller thread size on these pullers, IIRC, was the more common modern size. I always thought the larger size was just an obsolete euro size or something, but maybe it can be used on cranks where the threads have been damaged and re-tapped. If you had such a puller I am sure any machine shop could tap the threads for you.

Others mentioned a crank pulling system above that sounds like it taps your crank to accept a larger pulley. I am not familiar with any sytem for pulling out damaged cranks, but I am sure whatever this system is it is the cat's pyjamas!