Marzocchi Fork Steering Stem Removal

arancia said:
Wanting to polish the yokes, I'm trying to get the bottom yoke off the steering stem of an early 3C with 38mm Cerianis. I'd presumed it too should have the stem driven out downwards through the lower triple clamp but it's not budging even after several times left cooking in the gas BBQ very hot for a while.
In this case should it go out through the bottom? Stem looks like it may be about 1.5mm larger diameter on the underside than on top.
I don't have easy access to a press, is there a technique other than larger BFHs?
I got the lower bearing off with a pair of screwdrivers but otherwise this is what it looks like.
View attachment 62523
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Leave the steering stem be and polish.

Paul
 
Normski said:
Hi, can anyone tell me how to remove the steering stem from the bottom yoke on Marzocchi please? Is it a simple press out or is there anything holding it in?
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Hi Norman

Did you resolve the issue with the Marzo stem? I have the same issue with a yoke from a Mirage project.
On removing the yoke I found that the stem is u/s. Around a 40mm section of the thread is stripped, and the bearing locating surface has seen some heavy hands at some point, though damage to that isn't fatal. But the threaded section is.

So if it's feasible, I will get a replacement stem and press it back in. Or alternatively see about getting one machined up, if I can't get a s/h one.

Pete.
 

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alpinista1 said:
Hi Norman

Did you resolve the issue with the Marzo stem? I have the same issue with a yoke from a Mirage project.
On removing the yoke I found that the stem is u/s. Around a 40mm section of the thread is stripped, and the bearing locating surface has seen some heavy hands at some point, though damage to that isn't fatal. But the threaded section is.

So if it's feasible, I will get a replacement stem and press it back in. Or alternatively see about getting one machined up, if I can't get a s/h one.

Pete.
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If I recall correctly, that thread was machined like that ex-factory, it is the area to which the top yoke is clamped. You'd need a pretty big hammer to push the yoke over the complete thread. The lower bit of thread is utilised for adjustment of the bearings, the top thread takes the top nut. I think if you just check the fit of the yoke to the stem, you'll find all is well.

Your main issue is the seat of the lower bearing race, but, once the bearing is installed, you no longer see it. ;) I'd check if the stem is still straight, given that it's been butchered in such a manner...

piet
 
Thanks Piet. That hadn't occurred to me, but it makes sense. I will check the heights in the headstock, just to makes sure it lines up with the nuts.
I have checked that it's straight, and it was OK. Unlike a Ceriani stem on a 750 a few years back which had a 5 degree bend in it.

Thanks
Pete.
 
alpinista1 said:
Hi Norman

Did you resolve the issue with the Marzo stem? I have the same issue with a yoke from a Mirage project.
On removing the yoke I found that the stem is u/s. Around a 40mm section of the thread is stripped, and the bearing locating surface has seen some heavy hands at some point, though damage to that isn't fatal. But the threaded section is.

So if it's feasible, I will get a replacement stem and press it back in. Or alternatively see about getting one machined up, if I can't get a s/h one.

Pete.
Click to expand...
Hi Pete,
Yes I did. It needed to be pressed downwards as some said here. Damage from my wrong attempt was minimal and there was a small amount of galling as Breganzane warned. I needed it for the Egli so there was some machining done for 1” i.d. bearing and to shorten it a little - It went back together well with some loctite just in case.

I remember that bent Ceriani stem of yours - didn’t that come out upwards?
 
Thanks Norm, that’s useful to know. Can you recall whether yours had the smooth section on the threaded stem at all?
If that is normal, I won’t need to do anything further with it.
 
You're right there Norm. That's very different to mine. I don't have the pinch bolt for one thing. What was the donor bike?

I've had some more info and pics from Adam S today, as he's recently done his Series2 Jota head bearings. His stem appears to be identical to mine, in that there is a smooth section between two threaded sections. The smooth section is where the top yoke sits. If I look really closely at the pic of one on Andy Wagner's site it also appears to be the same.

It's been interesting to dig into this. Every day's a school day, as they say? The good news for me is that my yoke and stem doesn't need binning.

Thanks for your help with the responses. I hope the bikes are behaving. It will be a while before this Mirage sees the road, as it's been off the road for at least 5 years, according to the PO, and is well overdue for some thorough TLC.

Pete.
 
Just confirming what Piet said, the turned section of thread is absolutely normal for Marzocchi stems. There's two different thread sizes there, one for the top nut and one for the bearing preload collar. The latter thread root diameter is a little smaller than the diameter for the top yoke clamp, so it shows through. Nothing to worry about.
 
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