Ceriani forks 38mm

motoddrob

motoddrob

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S/W Australia
I'm having trouble removing the fork sliders off the stanchions. Yes I have removed the M6 cap screw!
As the forks have been stationary for over 10 years I'm figuring that the damper rod is well stuck in the slider.
So has anybody come across this problem and how did you solve it?

Cheers
Rob
 
M6 screw Rob?

There's a M8 or M10 allen screw that you access from the bottom of the slider that holds everything together. Once that's out, a firm tug lets it all fall apart. The screw can be a bugger to loosen and remove, best to try while the fork leg is still under spring pressure.

If the fork at least bounced a bit before dismantling, it should come apart quite easily. It is known that the piston on the damper rod can swell and jam inside the stanchion, only brute force will solve that. Should this be the case, have new pistons made up from a good quality aluminium alloy.

piet
 
Thanks Piet, had 6mm alan key in mind, yes it's a M8. I took apart another set of cerianis I had to re-familiarize myself.
I put the stanchions back in the triple clamps and with a slide hammer motion they came off so all good.
 
That sounds flash Hooksie.
As mentioned in previous post I have them apart. Tomorrow I'll pull the damper rods out and clean. I'll have a look at the pistons and the action.
Slippery is good(y)
 
Has anyone experimented with Andreani or YSS cartridge replacement kits for our old bikes? Brooks Suspension lists applications for several older Ducati models that might suffice. It would be nice to have adjustable compression and rebound.
 
hooksey said:
My money is on the swollen Piston on the damper rod.
Got some made in delrin Rob if ya find ya need some slippery ones…..👍
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Different issue to removing the sliders. That piston is held in by the big circlip at the bottom of the stanchion, accessed after the slider is removed.
Slider can be hard to remove if the damper rod is a bit stuck in the bump stop cone bit. Sometimes the bump stop bit comes out, other times it stays in the bottom of the slider.
To check if damping is even, when you assemble them, fill oil and draw down on sliders together, uneven wear will have one of them easier to pull down.
 
Careful when reassembling them, lots of wrong instructions out there. I think there is a correct assembly drawing on Laverdamania.
 
Correct Lee, it was the damper rod stuck in the slider. It all looks pretty clean internally. Tomorrows plan is to clean, polish and assemble with fresh oil and refit to the bike. Need to get the front wheel on so I can roll it back into the kitchen over night.
 
motoddrob said:
Correct Lee, it was the damper rod stuck in the slider. It all looks pretty clean internally. Tomorrows plan is to clean, polish and assemble with fresh oil and refit to the bike. Need to get the front wheel on so I can roll it back into the kitchen over night.
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Relieve the piston a tad.
They swell with time.
Paul
 
The swollen piston problem seems quite random. I have three sets of 38s and none of them suffer from a stuck piston. I think I only came across one when I was working on customer bikes. It could be that different quality aluminium was used and it was pot luck what you got.
 
Tippie said:
The swollen piston problem seems quite random. I have three sets of 38s and none of them suffer from a stuck piston. I think I only came across one when I was working on customer bikes. It could be that different quality aluminium was used and it was pot luck what you got.
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Was a pretty shitty grade of monkey metal, some sort of zinc alloy. I remember a new one gradually swelling and de-grading itself in the spares box over a couple of decades, first at Moto Witt, then at OCT. We just left it sitting, out of interest of what would happen. It was the only one out of several! I reckon it's still in its box, I'll take a pic next time I'm at OCT.

piet
 
Tippie said:
The swollen piston problem seems quite random. I have three sets of 38s and none of them suffer from a stuck piston. I think I only came across one when I was working on customer bikes. It could be that different quality aluminium was used and it was pot luck what you got.
Click to expand...
Correcto mundo.........You Luckeee bastard!
 
I had a problem with the slider sticking on my SFC 1000, dismantled the forks and found that the Teflon sealing ring on the piston had swelled and grown longer, snipped a couple of mm off the end and reassembled, problem fixed.
Obviously the material used was hydrolastic and swelled, not sure if it reacted with the oil in the forks or the moisture in the air. Anyway after giving it the snip and changing the oil all's well.
 
Alzero said:
Has anyone experimented with Andreani or YSS cartridge replacement kits for our old bikes? Brooks Suspension lists applications for several older Ducati models that might suffice. It would be nice to have adjustable compression and rebound.
Click to expand...
Racetech emulators are a popular mod & are adjustable.
 
IAG said:
Racetech emulators are a popular mod & are adjustable.
Click to expand...
I know, I’ve installed them many times, but require removal for adjustment. I was thinking of something like there for the conventional forks on the various 650cc Royal Enfields:

IMG_0317.png
Also available for 38mm forks.
 
I have seen first hand Ohlin’s cartridges in 38mm marzocchi fork’s. Was on a 120 Jota in Breganze that is owned by Werner the owner of the museum. So it can be done😊you just need the money 😂
Tom
 
sfcpiet said:
Was a pretty shitty grade of monkey metal, some sort of zinc alloy. I remember a new one gradually swelling and de-grading itself in the spares box over a couple of decades, first at Moto Witt, then at OCT. We just left it sitting, out of interest of what would happen. It was the only one out of several! I reckon it's still in its box, I'll take a pic next time I'm at OCT.

piet
Click to expand...
The problem is the damper bushings are made of Mazak metal which is a zinc alloy. If there are any impurities in the zinc such as lead, it will over time cause the Mazak to corrode internally and grow in size. The term for the problem is known as zinc pest from German Zinkpest "zinc plague". It was identified in the 1920's and was not supposed to happen in anything made after about 1960 after higher purity zinc alloys were developed. But you still see it in things made today as they figure the item will be thrown away before this happens and the low purity zinc is much cheaper.

My 3CL forks were a nightmare to take apart after the bushings grew in size. I made new ones out of aluminum. Wolfgang told me he has new bushings turning to dust on the shelf.
 
Once I removed the damper rod stuck in the slider the rest of it came apart as it should.
Now all spick and span and polished. Just waiting for seals and boots
 
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