Stuck Stem - opinions sought

[mattr]

Coke will at the very least etch the surface of the aluminum (changing its fatigue properties if my materials science is up to date), and could very well take any surface treatment off as well.
The inside of an aluminum can is coated. With stuff that is resistant to the acids. Bit like your stomach lining, continually deals with stuff that's as bad as coke.

 

[pigman]

Re: Re:

When I was a retailer back in the 60/70s i used to clamp the suitably protected fork crown in a large wood working vice, to eliminate twisting the fork blades.

Keith

Yeh, Ive done that too and was going to suggest it, but its likely that the steerer is glued (bonded) to the crown, so there might be a risk of breaking the seal

 

[Ian Raleigh]

Coke will at the very least etch the surface of the aluminum (changing its fatigue properties if my materials science is up to date), and could very well take any surface treatment off as well.
The inside of an aluminum can is coated. With stuff that is resistant to the acids. Bit like your stomach lining, continually deals with stuff that's as bad as coke.

Were not like talking about leaving the alloy soaking in coke for weeks you know!

 

[mattr]

Hours will be enough.

 

[FINNEY1973]

Re:

Nothing has worked, plusgas / coke / subtly applied force / long screwdriver from the fork crown entry and a whack with the mallet. Given the bonded fork crown, i'm not willing to go the whole hog of vice & full force. Not prepared to cut the stem a) the stem is obviously as one with the forks, no guarantee i can cut the thing out without making the preverbial pigs ear of it & b) it's too nice a stem to butcher.

So it's going to be a different groupset for the build, I have almost all of it anyway. Just means sourcing calipers, levers, new bars and a different 25.0 seatpost. Suddenly it looks a bit more expensive than I anticipated, but the end result will still be a treat.

BTW the coke was used progressively from 20mins to 2hours.

 

[mattr]

Just an idea.

I can remember having a frame maybe 25 years ago where the only way to get the bars in the right position was to actually slam the stem. Hard.
This eventually led to the taper of the stem wedging in the lock nut in the head set.

Might be worth just undoing the lock nut, see what happens.
When I did that, it took about 10 seconds to get the lock nut off the stem. Having spent an hour or two trying to pull the stem off......

Funnily enough it was a vitus 787.

 

[FINNEY1973]

Re:

The upper headset parts almost clear the steerer when undone, i've tried hitting down onto the stem knuckle with the headset undone as far it will go, similarly with the headset parts loosely wound down onto the steerer. It must be a mighty chemical reaction that has occurred for the parts to have fused as they have. Really rather infuriating - It took 12 months to find a frame in the right condition & colour. I passed up two others, as they had a few too many flaws. Hindsight is not a wonderful thing!

Interesting yours was also a Vitus - something in the particular alloy perhaps or merely a statistical likelihood?

 

[danson67]

OK. In the interests of RB, I've had a look at the fork on my 979 (1987, 52cm, sky blue).
The steerer is definitely steel, not aluminium:

So some of the thermal ideas might be a good start after all. The bonding interface with the cast alu crown is at least 40mm long. The steel steerer runs down past the brake hole, so fit a front brake if you're worried about any twisting risk.
Also, it those methods don't work, it's easy to feel the alu/steel interface if you go for the longitudinal slicing method (as used on many a seat post).

Trashing a good stem will be considerably cheaper than sourcing all the other parts, and you'll be able to service the headset.

All the best,

 

[Midlife]

If you can see a bit of the steer tube will a magnet stick to it? Might confirm that it's steel and not alloy.

Shaun

 

[FINNEY1973]

Oh to be able to see my forks like that thanks for taking the time to post the image.

Only got a very small magnet but it doesn't stick to either the threaded part or at the crown. Could be the fact i'm using a wheel magnet :facepalm:

Mine is a MK1 979, did they alter the materials when they introduced the MK11?

http://www.equusbicycle.com/bike/vitus/ ... re%203.pdf
http://www.equusbicycle.com/bike/vitus/ ... re%205.pdf