Steering stem cracks

[mark vb]

I keep coming back to look at this, are there two cracks oposite each other and slightly offset from the straight ahead position?
I'm thinking that the largest load is turning left where the weight is transfered forward and to the right hand side and that appears to be the plane that the damage is done.
I've never had a close look or ridden a sidecar with conventional forks but I'd have thought the rake angle would lift the front tyre towards it's edge using a flat carcase tyre.

With reference to a clock face, with 12.00 at the front of the steering head, the cracks are....
- The double cracking (i.e. the large and small
cracks which are close together) are at approx.
8.00.
- The middle-sized crack is a touch after 12.00.
I am determined to get to the bottom of it!

[Snaf MKII]

Yes, I'd like to know as well. What brought you to change the bearings. Were they notched and if so was it straight ahead or a bit to the left.

[Asgard]

It's odd, really looks like someone use something to knock/pry up the old race from below to remove it and went into the steerer
don't see how it would tear in that place and it isnt a crack

[mark vb]

Yes, I'd like to know as well. What brought you to change the bearings. Were they notched and if so was it straight ahead or a bit to the left.

The first time I changed the bearings (at around 33k miles) the bike was still solo - there was typical notchiness evident when turning the bars with the front wheel raised off the ground, the notchiness being at 12.00 (straight ahead). All very normal.
Second time round, with the chair having been fitted for over 7 years, was a bit different. Play in the bearings alerted me to the fact they needed adjusting. Steering was a bit stiff (with the wheel raised off the ground) but no notable notchiness. The play could be got rid of by adjusting the bearings, but when the play was gone the steering was incredibly stiff.
First time round, the notchiness could be seen where some of the balls had slightly indented the cups. Second time, ie. now, there are no discernible incidents on the cups. So, rather different to the first time!

[mark vb]

It's odd, really looks like someone use something to knock/pry up the old race from below to remove it and went into the steerer
don't see how it would tear in that place and it isnt a crack

As mentioned, I'm the only person who has changed the bearings since the bike was new, so I can say with 100% certainty that a chisel hasn't been used to knock/pry-up the cup! Both times I've used a cutting wheel, using a cold chisel to make a final blow on the cut, to crack the cup. The chisel has been aligned to the cut, which itself was made at an angle of around 25-30 degrees, ie. not horizontally across the stem, which the three cracks/tears/fissures are.
I agree the term 'crack' is probably not entirely appropriate.... split or tear or fissure is probably a better term.

[catcitrus]

I cannot understand why the "cracks " are so open yet there appears to be NO deformation of the stem (alignment) that would cause them to open, and no hairline cracks either side which you would expect. To me they just look like nicks from a cutting disc. However, replacement is the best cure.

[qcnr]

They are not going to 'heal' themselves.... No matter how they appeared.

[mark vb]

I cannot understand why the "cracks " are so open yet there appears to be NO deformation of the stem (alignment) that would cause them to open, and no hairline cracks either side which you would expect. To me they just look like nicks from a cutting disc. However, replacement is the best cure.

Exactly - the 'cracks' are very open and there is no discernable deformation of the stem which would cause them to open. I can categorically say they haven't been caused by a cutting disc. It may be hard for third parties to accept this as fact, but I can say with 100% certainty that the first time I removed the cup the stem had no nicks or cuts caused by an errant wheel. The second time I removed the cup, my Dremel wheel was kept at an angle of 30 degrees in one place - in contrast to the three horizontal 'cracks', one of which is approximately opposite the other two. If you saw the 'cracks' in the flesh you would know they are not from a cutting disc, I can assure you
Anyhow, I have got another stem. I'm going to get the original checked out by a metallurgy lab to try and cast more expert light on the 'cracks'.

[mark vb]

They are not going to 'heal' themselves.... No matter how they appeared.

No, it's not a rare magic stem At least not as far as I'm aware.... that's why I've now got hold of a replacement

[catcitrus]

I look forward to the metallurgy report on this interesting "fault"--perhaps try some two part crack detector in the area---red dye, wipe clean and then white developer--the red die will soak through from the crack and show up against the white overspray.