Steel in aluminium. Heat or cool to separate?

brocklanders023 · Aug 8, 2018

Hi all. Had some bother removing a drive side crank. To be fair my extractor was weathered and the second option was a Aldi special but either way it hasn’t shifted. Thing is the frame has come up really well so i’d like to build it with my choice of parts as originally planned so need the current DX crank off.

Before I resort to the bike shop I plan to either heat or cool it and try again. Question is, with a steel axel in a aluminium crank which way should I go for best results?

michael franks · Aug 8, 2018

Re:

I've got a similar problem to yours - steel pedal axle stuck in aluminium crank - and I think the way to go is to heat the area and as aluminium expands faster than steel it should loosen the corrosion. Shock treatment ie: the judicious use of a hammer might help it along.

I suppose you could also freeze the steel axle and there's an interesting vid here:

https://www.youtube.com/watch?v=0PeK7VfUMAI

but I'm not totally convinced by it. I wish you luck with your difficulty and I think patience plays a part in it as well.

brocklanders023 · Aug 8, 2018

Re:

Thanks Michael, that makes sense. Heating is easier also and I need a new extractor!

MR OX · Aug 8, 2018

Re:

It's an obvious question but have you tried Halfrauds "shock & unlock" spray? I've had some good results with it.

brocklanders023 · Aug 9, 2018

Re:

Not yet mate but will now.

KermitGKona88 · Aug 9, 2018

Re:

No heat,no cold, just these

https://www.ebay.co.uk/itm/Drill-Chuck- ... 2544446065

JonTom · Aug 9, 2018

Re:

Pop the kettle on.

Slowly pour the boiling water over the end of the crank by the BB or pedal, and try removing again.

The heat will expand the alu just enough to free the steel.

Might take more than one go but you can have a cuppa and a biscuit while you're doing it.

Retro Spud · Aug 9, 2018

Re: Re:

kermitgreenkona88":otn8m00k said:
No heat,no cold, just these

https://www.ebay.co.uk/itm/Drill-Chuck- ... 2544446065

Are you speaking from experience or that they look like they might work

I can see the advantage of these wedges pushing and perhaps an extractor pulling you’d get a bigger bang for your buck, but if your extractor cannot be used I can’t see these working without a lot of brute force and potential damage from a mid guided hammer blow

Like the concept and the added push power here and will be following this thread closely as I too have a similar problem

elite504 · Aug 9, 2018

Exactly what Michael and Jon Tom said.

thummie · Aug 9, 2018

Re:

Had some topline cranks that had not been move for 15 years and stuck solid.
Using a ball joint splitter and a spare crank bolt, I put as much tension on the crank as I dared.
Then applied gentle heat to the crank with a heat gun. around 30sec later the crank popped off. Reckon the crank was no more than 40 degrees C when it let go.

Steel in aluminium. Heat or cool to separate?

brocklanders023

michael franks

brocklanders023

MR OX

brocklanders023

KermitGKona88

JonTom

Senior Retro Guru

Retro Spud

elite504

thummie

Dirt Disciple

Similar threads

Latest posts