Alloy stem vs steel steerer

Hi there, I have an alloy stem stuck in a steel threaded for steerer.....any advice getting the two to part?.....the centre pin and wedge thing are loose and free, but they seem locked together.....on two frames I own! :?

Give me a lever long enough and I can shift the world. But some Penetrating oil or coke would probably help in this case.

Ammonia can dissolve aluminium corrosion, try blocking the stem bolt, turning the bike upside down and filling the steerer with ammonia. Go easy on the twisting, it's really easy to bend/twist light rorks. Use a bit of wood between the top of the fork legs rather than the wheel to twist against. This reduces the risk of twisting the forks blades.

Failing that, a nuclear option that has worked for me in the past is; saw off the top of the stem leaving 4cm of stem poking out. remove forks from frame. blowtorch steerer, aiming to get it to the point just before it turns red. dunk the stem-stump in ice water to just before the steerer. the stem then cools more than the steerer, when the water stops boiling off the stem put the stump in a vice, should twist/pull right out.

This should only really be done if you absolutely have to, it's a pain in the arse and dangerous! You could also use caustic soda to dissolve the aluminium but that's even more dangerous/annoying

hey Eastsidebikes, are you Dr Frankenstein by any chance?

I have put together some zombie bikes in my time