pstock

I am turning to you all in a last ditch appeal for help with an incredibly stubborn stuck stem and fork.

In the past year I have defeated about 5 seriously stuck seatposts and 4 stem/fork tubes, some of which took weeks of soaking to free. But this one, after two months, has be stumped.

So far I have undertaken the following measures:
1. soaked it both sides in Liquid Wrench.
2. removed the bolt and plug from the stem,
3. heated it with boiling water (per Dave Moulton)
4. I have replaced the handlebars with long metal pole to get excellent leverage.
5. I have (carefully, or as carefully as I reasonably can. and I have them locked in at the shoulders so I think it should be solid enough) locked the fork blades in a wooden Workmate bench vise.
6. filled the headtube with diesel fuel for 2 days.
7. frozen it (handily, it is freezing here in Toronto so I just left it outside for a few hours.)
8.I have bashed it hard with a sledge hammer (to break up the bond?), dropouts on concrete, stem protected by a block of wood (I'd rather not trash the stem.)

About 2 months ago, after the liquid wrench drenching and heating (step 3) I got an encouraging CREAK and small bit of play.
then it seemed to seize right up again.

this week, after 2 days of diesel fuel soaking, freezing, bashing, I got another CREAK and a little more play. But then it seized right up Again (I can't figure this out - I would think that if it started to move, it should stay movable... I am guessing that if the surfaces are really rough in there, it could get stuck again in a new position?)

it should be noted that the the frame to this Colnago is already seriously damaged (cracks and holes in the down tube) and so would need serious refurbishment anyway.

But I would like to recover the forks and stem. someone could use them.

HELP!?

Peter

Andy_K 

The only thing I can think of that you haven't tried is soaking it with ammonia.

I got a stem like this loose by riding it for a couple of months after doing pretty much what you describe above and giving up.

bikeman715

I agree with Andy_K ,ammonia should do it. Note, not the ammonia you buy at a supermarket but at a hardware store, it stronger stuff.

FBinNY 

Ammonia is very effective with aluminum/steel galvanic corrosion. Unfortunately it should be done as a first, not last resort. Once the parts are thoroughly soaked in oil the ammonia won't wick down to where you need it.

The fact that got a creek is a hopeful sign, but the problem with severely galled parts is that any movement can worsen the galling.

Here's one last ditch thing you can try. Loosen the locknut on the headsee and see if it can move up an eighth inch or so, though the stem seems to be pushed in all the way. If there is some room to push the stem deeper, that's exactly what you're going to try. But you have to do it right.

Brace up the fork on a length of pipe or bar stock, with the other end solidly braced agains something with lots of inertia. An anvil would be best, but a good sized boulder, or even a hard tree stump you're using for splitting wood. The key is to have a zero give fixture that will concentrate any hammering effort in the steerer and stem.

Now use a heavy hammer, if 3 or more pounds, and deliver a serious blow to the top of the stem. You don't want to use just one killer shot, not try to hammer it down with multiple blows. If you can move it, that'll break all the bonds. Soak it in cutting oil thinned naphtha so it'll wickm in. You want cutting oil because it has anti galling additives to prevent fresh galling as you try to work it loose.

Finally fixture the crown itself in a bench vise (protected with leather or hardwood) Fit a wrench over the back of the stem, using the extension as flats so you have a purchase, Twist and see if it moves, if so continue , but keep it oiled and cool by resting between each effort. Once it's moving have a friend hold and pull the extension as you work it back and forth and see if it rises. Do not let it get hot. Stop for a beer every few minutes, and 2 beers when you succeed.

LarDasse74

Something I have done that works when you don't need to save the stem is multiple rapid maniacal blows to the underside of the stem with a metal hammer. It'll mangle the stem but, goddamn, it'll come out.

pstock

Oh and I should have added, that the only other trick I have tried on other stuck stems was to bash them out from below, by sticking a length of 1/2" pipe up from below between the fork shoulders, and knocking it out that way.

the only reason I haven't tried this in this case, is that there is a 1/3" pin jutting into the lower end of the steering tube, from the front end, down by the fork shoulders. that would block a pipe and I am not sure I want to knock or cut it out in case that somehow ruins the fork.

I'll have a look at another Precisa fork and see if that is standard.

pstock

actually the stem is not pushed in very far. That is a photo illusion since I released the headset top nut. there's lots of room

mechBgon

I'd lop off the stem with a hacksaw, remove the fork, and plunk it upside down in a container of lye for a few days. It'll eat the aluminum and leave the steel.

pstock

Good suggestions.
Though I need a couple of clarifications.
when you say "Brace up the fork on a length of pipe or bar stock" do you mean, length of pipe parallel to and between the fork blades bracing up under the bottom side of the headtube? as per attached?



Second, when you write "You DON'T want to use just one killer shot, not try to hammer it down with multiple blows." did you mean "you DO want to use just one killer shot"? I presume that was a typo.

Thanks

Peter

FBinNY 

Yes, you want to support the base of the steerer tube directly so there's zaro stress on the crown or blades.

Yes, you do want to do it in one killer shot. It wasn't a typo, just sloppy editing.

Remember to not let it warm as you work it loose, or it may jam again.

zebede

Since you have exposed a portion of the fork tube, I would consider heating the fork tube with a propane torch, being careful to stay as far away possible from the fork crown.
After It is hot as possible with propane (not map gas, not oxy, acetylene Unless you were very careful to not overheat) I would douse liberally with cold water. The expansion contraction
may break the bond.