Stuck Raleigh steering tube; options short of cutting it?

[mcswell]

I'm rebuilding a Raleigh road bike. I've succeeded in taking everything apart except for the seat post and the steering tube. I'm not worried about the seat post; the height was good for me ten or twenty years ago, and my legs haven't changed. I'm less sure about the quill stem--it comes to the right height, the steering seems to turn smoothly, and this site: https://sheldonbrown.com/raleigh26.html says "The stock Raleigh headsets have proven to be unusually long-lived, so it will rarely be necessary to replace one."

But I found grit in bearings elsewhere on the bike, so I'm a little concerned.

The wedge moves, but the aluminum quill is thoroughly "welded" (as is the aluminum seat post). I've tried almost everything short of heating it with a torch or hacksawing it out, and I'm resigned to leaving it in there. But I'm thinking I want to clean the bearings, and possibly replace them, without removing the quill (since I can't). The BBs are loose (no retainer), and of course there's an upper and a lower set. By unscrewing the headset, I can get the BBs out. My thought is to replace them (4mm, at least the lower ones are), then flush out the races with WD-40, let that evaporate, and add the new BBs and grease.

Does this seem reasonable? Am I missing anything?

[peetee]

I wouldn’t like to trust a corroded stem so would take steps to remove it altogether. I would suggest you cut of what is visible - leaving a straight section if possible - and after removing the forks from the frame, soak the steerer tube in caustic soda solution to dissolve out the remaining stem section.

[TheBomber]

You’ll be wanting imperial sized bearings for a bike - so your ‘4mm’ will be 5/32”. Given the age of the bike I won’t rant about the ridiculous nature of that number.

[ed.lazda]

People who tinker with old motorbikes seem to use blowtorches quite readily to remove stuck bits, so I wouldn't rule that out. At worst you might need a new paint job. If you want to be a bit more gentle, a hot air paintstripper gun might do the job. Aluminium expands more than steel with heat, and repeated heating of the stuck part, with application of release agent and a bit of physical violence between cycles, might help unstick things. On reassembly, apply copper grease (my Thorn Mercury manual says seatposts should be greased every year). Good luck.

[peetee]

I wouldn’t attempt to heat a very thick chunk of aluminium that is wedged inside a very thin cylinder of steel.

[531colin]

I wouldn’t attempt to heat a very thick chunk of aluminium that is wedged inside a very thin cylinder of steel.

……,that is itself contained within another thin-walled steel cylinder, the frame head tube, with an inconvenient air gap

[PT1029]

It isn't the heating and resultant expansion that unsiezes it.
The aluminium oxide is hydroscopic, so absorbs water, which makes it expand and so siezing things up. When heating, the heat dries out the damp oxide causes it to shrink, reducing the tightness of everything, even unsiezing it.
As Colin says, the head tube is inconveniently in the way with its inconvenient air gap.
Something I have pondered but never tried is this. Take a metal bar that will fit up inside the fork column/inside the handlebar stem. Heat the bar so it is really hot and stick it up inside the fork column, possibly repeat a few times. Once the oxide has dried out and thus contracted, you might be able to remove the bars/stem from the forks.
If you can let the stem wedge fall out of the bottom of the forks, even better.
Once "dry", using a suitable unsiezing oil might help before you start to heave on things - apply oil, leave, re apply and repeat over a week or 2 if needed.
Suitable unsiezing oil does not include WD40 out of a blue can.

[mcswell]

Thanks for the replies. I'm going to stick with the seat post and stem, but replace the BBs and clean out the races. Thanks for the advice!

(and thanks to TheBomber for pointing out that they're 5/32" BBs)

[Brucey]

if you warm up anything Al that is stuck in steel two things happen;

1) the oxides which are causing the seizure start to dry out.
2) the Al will expand faster than the steel, and may start to yield. This is called differential thermal expansion (DTE).

1) means that the grip of the oxide will eventually reduce if it is heated for long enough. I had it in mind to try heating using a very low power for several weeks but I don't suppose I ever shall now. If the Al starts to yield this means it will shrink slightly and this in turn means it will be a wee bit looser once it has cooled again. If you can find some way of applying a straight pull to either the seat post or the stem eg. using a hydraulic jack, then your time is unlikely to be wasted.
DTE can induce about 0.2% strain at about 200C and this is probably above the elastic limit for most Al alloys at around 200C. If you can heat to ~150C and hold for some time the paint may survive. Cooling is likewise beneficial; if you can drive off most of the moisture using heat, then use liquid nitrogen on it, it should be easier to extract the offending item.