Struggle with siezed stem or just service headset bearings in situ?

[SkipdiverJohn]

One of my salvaged cheapo MTB's is really getting on my nerves. Sod's law it's the one of the two that actually fits me very well with a 22" frame - and not the slightly smaller one that came apart relatively easily!. The handlebar stem is seized solid inside the headset tube, and the application of penetrating fluid and big hammers have so far failed to persuade it to free off. This bike is really badly neglected and was obviously an open-stored commuter hack before being abandoned; I had fun and games this afternoon even just getting the brake calipers off the tube spigots.
Although the seized stem is a nuisance, the bars are actually set at a pretty comfortable height for my size, so I'm thinking possibly of taking off the top headset race, extracting the balls, then dropping the forks with the stem stiil in, to release the balls out of the lower race. Any reason why I shouldn't just do this, repack the races with fresh grease, and reassemble the headset without first removing the stem?
I've got a D-lock (with no key of course!) left locked around the top tube and down tube, so I'd really like the stem off so I can remove the lock from the front of the frame without having to bust it or cut it, but it's not currently looking promising. I'm stubborn though, I don't like to give up too easily.

 

[Smokin Joe]

Assuming an aluminium stem try some ammonia rather than penetrating fluid. Apparently it breaks down corrosion on alu.

 

[SkipdiverJohn]

Assuming an aluminium stem try some ammonia rather than penetrating fluid. Apparently it breaks down corrosion on alu.

No aluminium bits whatsoever on any of my machines apart from the wheel rims on the MTB's. All low-cost, low value bikes. You wouldn't be able to keep hold of anything nice for more than 5 minutes where I live anyway.

 

[BalkanExpress]

If it is steel try Coca Cola, again the idea is that the acid will dissolve the rust.

 

[lazyfatgit]

^^ Coke worked for me in a similar situation.

 

[Drago]

50/50 mix of acetone and automatic transmission fluid.

 

[Tim Hall]

50/50 mix of acetone and automatic transmission fluid.

94.3% ammonium nitrate and 5.7% fuel oil.

(No. Don't try this at home, at someone else's home or any where else)

 

[gazza1286]

It's a question of leverage. Assuming this is a quill/wedge type - the handlebars need to supported from underneath on something really solid such that the front wheel is off the ground. This means that any force applied to the wedge bolt isn't 'absorbed' through the suspension/tyre. A swift downward strike will dislodge the wedge without any bother.

 

[Ajax Bay]

It's a question of leverage.

I see no moment here. Maybe rather a question of percussive force (but agree with your recommended attack method).

 

[Tim Hall]

I can't see any reason not to clean and re-grease the races in situ. Provided that you've figured out a way to remove that D lock. Then unfreezing the stem can become a problem for another day. Perhaps never.

Although, if the balls are in a cage in the fork crown bearings, then removing and replacing the balls could be slightly fiddly.

Cut the cage and bin it. Replace with loose balls.

 

[Drago]

94.3% ammonium nitrate and 5.7% fuel oil.

(No. Don't try this at home, at someone else's home or any where else)

You'll need about 1% ground charcoal to do an effective job. Mix it to a consistency that when squeezed in the hand it just retains its shape.

 

[SkipdiverJohn]

A swift downward strike will dislodge the wedge without any bother.

The wedge nut isn't the problem. Its dangling loose on the end of the expander bolt once slackened.

I think some of the chemical solutions are a tad drastic; I just want to separate the parts not blow the whole thing apart!

 

[Tim Hall]

The wedge nut isn't the problem. Its dangling loose on the end of the expander bolt once slackened.

I had this on my Mercian. I got them to sort it when I had it repainted.

 

[SkipdiverJohn]

It appears my mum was right all along and patience is a virtue. After repeatedly squirting the seized MTB stem with penetrating fluid and clouting it with a big rubber mallet every few days for six weeks it finally freed off this afternoon with nothing more dramatic than a gentle "ping" as the jammed parts loosened off. The expander bolt and wedge nut are red rusty, cannot believe just how rusty considering this is actually the newest of all my bikes and was the only one I had such trouble dismantling. Everything is getting well covered with lithium wheel bearing grease before it goes back together, don't fancy a repeat of all that hassle!.

 

[tyred]

The easiest way for a steel stem is to turn the bike upside down, remove the mudguard if there is one and pour diesel into the steerer tube and let it sit for about a week. Diesel works well as a penetrating fluid and is very cheap.