Stuck/fused pedals. What’s the solution?

[The History Man]

Thanks to all. The heat is the way forward methinks. I have a five inch 40lb engineering vice affixed to a 6ft workbench with 3ft of shelving on top of that. I am large. I moved the whole lot with adjustable sleeved with pole. This was after a bit of a soak.

been soaking in plusgas for two days since.

 

[The History Man]

Cranks are removed from frame.

 

[legrandefromage]

...and the cat is in the basket

I repeat

the cat is in the basket

 

[fearfactoryüberalles]

Take the pedal apart, only the spindle must remain. Secure the spindle in the biggest/strongest mofo vice you have access to. Even better to have a 15 mm spanner, put it in the axle, then tighten the spanner's head horizontally in the vice - make sure you don't mind to scratch/deform it a bit due to the brutal method-this way the spanner stabilizes the axle from rotating as it works against the vice nicely.

Now get a steel tube (more like a pole), with a suitable inner diameter (depends on if LHD/RHD crank)- ideally a bit thick walled- to use it as a lever, and with soft padding (avoiding crank damage) just slide the crank into it. Get freezing spray and spray the crank 'till it looks icy. Make sure you turn it into the right direction-remember now you are seeing the crank from behind-it can be pretty deceiving. Turn the pole with the crank in it. It should pop. IT MUST POP!!!

 

[fearfactoryüberalles]

About the heating method which was kindly suggested by some-I don't think it does any good to the cranks-freezing also breaks chemical bonds and much more safer/healthier-for crank and its owner too.

 

[The History Man]

So, spray it with butane lighter fuel?


maybe not heat it.

 

[The History Man]

And you can’t put a pole over rhd spider.

cranks in vice.

 

[The History Man]

...and the cat is in the basket

I repeat

the cat is in the basket

When you coming home son I don’t know when…..

 

[hookooekoo]

If the cranks were to be frozen, then in theory the spindle hole in the crank will get smaller more quickly than the spindle gets smaller. At least I think that's how it works. The expansion coefficient works in reverse for cooling too, but it creates a contraction instead of an expansion, so the crank will grip the spindle even tighter. I can accept that cycling the temperature from cold to hot might help break up the adhesion that has occurred due to corrosion. However, I wouldn't try loosening it when it's cold, because in theory the crank is gripping the spindle even more tightly.

You could try buying some freezer spray, but it's expensive, so you might as well just try putting it in deep freeze under the frozen peas. The ultimate would be to immerse the whole thing in liquid nitrogen (77K). Liquid nitrogen is very cheap, as it's generally considered to be a waste product from the fractionation of liquid air*. However, you'd need to know someone who worked in one of the few labs or industries that uses it to get access. Second best would be dry ice (solid CO2) in a methanol bath (195K), but again, most people can't access that. On the other hand, most people have access to a hair dryer or a heatgun, and it costs nothing more than a bit of electricity.

* Nitrogen is approximately 70% of the atmosphere, so oxygen and all the other rarer gases are much more valuable.

 

[novocaine]

Without a forge you are not going to do anything to the cranks with a bit of heat from a heat gun. Crack on and stop chattin about it.