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Aluminium seized in steel

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Alfie Peacock04/05/2017 00:18:54
24 forum posts

Hello

I have a 1960s cycle frame and the stem is seized in the steel tube, any ideas how to free the stem from the tube.

I have tried heat when the tube very cold but its stuck fast.

I could get it done by a cycle frame refinisher but its quite expensive to be done.

Thanks for any replies.

Ady104/05/2017 00:53:51
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2800 forum posts
368 photos

Have you taken the bolt and collet out?

The bit that expands as the stem bolt tightens? and holds it in the frame?

If the bolt is out the expanding collet bit may be stuck and need some hammer work, stick a bar down the hole in the stem and give it a few good solid taps

edit: No, on hindsight, refit the bolt loose, then bang it on the top to unseat the expanding collet

Edited By Ady1 on 04/05/2017 01:17:33

Alfie Peacock04/05/2017 01:43:28
24 forum posts

This is not a simple dismantle of a bike stem, its corroded up. Steel with aluminium dont mix.

Jeff Dayman04/05/2017 03:29:36
1000 forum posts
21 photos

Hi Alfie,

As you probably know, if these parts have been together a long time in wet conditions there is a chance they are chemically bonded permanently. There may be an electrical / electrolysis trick that could work to reverse the reactions but I don't know it. You could try the old standby mechanical solution - put the handlebars on the stem, take a pneumatic hammer with a blunt chisel tip, and apply it to the outer end of the handlebar, then the other end. The vibration may shake it loose, and using the handlebar will give you some leverage to get more torque on the joint. A leather glove or block of wood between chisel and handlebar will prevent marking the bars. If you've got a friend to help hold the frame and apply some penetrating solvent/oil mix like WD-40 or diesel fuel/transmission fluid mix to the joint as you use the pneumatic hammer that may help. It may take a few tries over a few days to get it apart like this, but keep trying and it will likely come apart, unless a permanent reaction has happened as mentioned above. Failing all that, the aluminum could be carefully bored away and a new stem made.

Good luck JD

John Haine04/05/2017 07:03:22
1462 forum posts
89 photos

This happened to me on an old bike though newer than from the sixties. IIRC I removed the saddle from the seat post and applied WD40 and lots of wellie from a mallet.

Note to self: when I get home remove post from current bike and relubricate.

JasonB04/05/2017 07:36:38
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Moderator
11084 forum posts
991 photos

I have seen it done by holding the bike upside down and melting the alloy out. Needs care if the lugs are silver soldered

A 60s bike is likely to have a wedge type fixing so slacken the bolt in the middle of the stem and then give it a tap this may loosen the usually steel wedge which could be what has rusted rather then the stem corroded but it is more likely a reaction between the two metals that will be hard to break.

third option is to undo the headset to expose some of teh steerer and saw through it, take to frame builders and get them to fit a new steerer tube into teh fork crown.

A lot will depend on what the bike is, if it is just your old school bike you fancy having a ride of then may not be worth it but if on tehother hand it is a nice classic lightweight with fancy lug work then better to get it done by someone with the right gear, atthe very least the steerer is likely to need reaming to clean up the surface and headset replacing.

J

not done it yet04/05/2017 08:21:51
930 forum posts
3 photos

I have tried heat when the tube very cold but its stuck fast.

 

I've no real idea, but the above seems 'back to front'.

 

Better to heat the steel then cool the ally to break any joint between them? Coeff's of expansion being different?

Edited By not done it yet on 04/05/2017 08:23:03

roy entwistle04/05/2017 08:33:06
668 forum posts

There seems to be some confusion here as to whether it's the saddle stem or the headstock

Roy

Emgee04/05/2017 09:23:50
573 forum posts
152 photos

Hi Roy, believe it's the headstock from description.

Emgee

J Hancock04/05/2017 09:31:45
130 forum posts

Sounds like the aluminium has behaved as the sacrificial anode and has 'grown' into the steel.

I do not think you will get that apart without ' breaking' something.

Were it a simple tube , a thin grinder to split the tube and reweld but not so in this case, I fear.

Neil Wyatt04/05/2017 09:40:48
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Moderator
10694 forum posts
493 photos
60 articles

I'm assuming the frame is precious and the stem, (whether seat or handlebar) can be lost.

Invert the frame, put it over a plastic tray and plug any holes so you can fill the affected area with water without it dripping out.

Empt out the water and replace it with caustic soda solution and leave for several days. It will erode the aluminium without attacking the steel, and should hopefully get in between the two metals and loosen the joint, which won't be 'welded' but packed with aluminium oxide .

This will probably take the paint off as well but is less likely to cause damage than mechanical methods.

The other way is to use a piloted drill, but even a few years can be enough to lock a stem solid, fifty+ years will be a challenge.

Neil

john carruthers05/05/2017 08:46:28
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466 forum posts
167 photos

A cheap 'Oven Cleaner' from Aldi et al will disolve aluminium very well, especially when hot.

(don't ask how I know this )

Jeff Dayman19/05/2017 00:38:30
1000 forum posts
21 photos

Looks like Alfie the OP has disappeared. Too bad, was interested to hear what he did with the stuck stem. JD

Michael-w19/05/2017 06:21:58
1704 forum posts
48 photos

a hydraulic press would be my safest bet if it were available.

Michael W

Matthew Reed19/05/2017 08:15:44
39 forum posts

 

I would keep trying with heat, based on my experience with musical instruments. It may not work here, tbh, but it is different thinking.

But it isn't about getting a heat differential, in getting the inner tube to shrink through cooling etc, but about breaking the 'chemical bond'. Just heat the whole thing as hot as you date. The different metals, and the oxide, will all expand at different rates breaking the seal between them. Even the different diameter of the tubes causes the expansion movement to differ enough to crack the bond. In thin walled brass and nickel silver, such as trumpet tuning slides, you can 'hear' things have changed when you tap it (perhaps 'sense' is more accurate, so please don't ask me to ask explain.)

Just get it as hot as you dare, then cool quickly, leave for a while, and repeat a few times. When you think it might have changed, flood with whatever lubricant or anti corrosion chemicals you fancy and apply 'No1 tool' in an appropriate direction.

No idea if this will work, but it's where I would start: the musical world often uses 'different' approaches.

As a second thought... cycles, especially older ones, are notorious for having strange/obscure/hidden fixing methods. Are you sure there isn't a bolt/cotter/strange-grippy-bit somewhere? I also seem to remember a fashion for welding/brazing such joints on touring bikes as a common 'upgrade', once the position was established: it's not a field renowned for good engineering practice!

Edited By Matthew Reed on 19/05/2017 08:18:46

Mick Berrisford19/05/2017 17:01:59
99 forum posts

Another vote for caustic soda . Just take the right precautions - glasses and gloves minimum as it's nasty stuff.

John Reese20/05/2017 17:58:07
327 forum posts

If it has a bolt hole through it, just drill through it with successively larger bits until the wall is quite thin. Shove an awl between the steel and aluminum to break collapse the aluminum. No nasty chemicals.

If it is a relatively thin walled tube, use a hacksaw blade to cut through the aluminum wall in 3 places. Cut just until you reach the steel. Use an awl to collapse the aluminum into the hole.

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