Ceriani rear shock absorbers

michipons

michipons

Hero member
Location
Palma de Mallorca
Dear all,

I have restored my old ceriani shock absorbers, I used the seals provided from Wolfang, re-chrome the springs, and repainted everything, they look great... 8)

According to laverdamania, the oil quantity is "full" and viscosity should be 20W.

I found only fork oil density 15, so I put this one. On the other hand regarding the amount of oil, teh term "full" is a bit relative, lets see if I can explain myself: when the shock is compressed, the rod slides into the bottle, thus reducing the available volume of the bottle, that means that if the bottle is full, there will be no "space" for the rod to slide in, so what I did was to put it full, then slowly compress the bar to the end, letting the extra oil to go out, then I closed the seal, on this way I am sure that the bottle has an amount of oil that allows the rod to go in.

Until now all good, but when I test them in the work bench, I have the impression that they rebound veeeery slowly, when I increase the preload of the spring, it rebounds a bit faster. May be with the weight of the bike and the preload, it improves, but I am not sure.... Any ideas or suggestions? I never tried ceriani absorbers before, but if I compare them to my koni in the le-mans or the Laverda 1000, those rebound much faster. After all the work I did, I would like to avoid buying a new pair of Ikon.

I was thinking to change the oil for a 10 or a 5, but that is a huge difference to what is recommended in Laverdamania...

Regards,
Miguel.

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Lovely job Miguel. One I never dared undertake, so I sold off all my Ceriani shocks.

A little light at the back of my brain from a long time ago says 80cc of oil.

Paul
 
For the 3c Ceriani shocks AFAIK oil should be as follows:
Total oil amount appr. 115 ml (of which appr. 35 ml in the outer tube and appr. 80 ml in the inner tube).

Grade of 15-20 sounds to thick - I would rather prefer something between 5 - 10 ...

Cheers Jo
 
Thanks to all,
So I was not so far from the path! I meassured 95cc (using the strategy described), regarding distributing the oil between the tube and between the wall and the tube, I think it doesnt matter, once you strut and extend a few times, the inner tube is allways full and the rest is out... (between the tube and the bottle).

Thanks Grant, Laverdamania says 20, I used 15, and I have the impression it should be less, as you say, 10 or even 5...

I think that now that I have them already attached to the frame I will wait for a ride test and eventually do some modifications if necessary.

Regards,
Miguel
 
Excellent job rebuilding those, Miguel. Did you have to re-hardchrome the shafts or are they original? Thy look in excellent condition. Hope you manage to get the right damping happening after all that hard work.
 
Nice work Miguel.
The rebound damping on my Ceriani rears is also very stiff. 
Was like that with the original shocks, and also after I rebuilt them.
I seem to recall that I used 100ml of fluid.

Tom
 
Piranha Brother 2 said:
Excellent job rebuilding those, Miguel. Did you have to re-hardchrome the shafts or are they original? Thy look in excellent condition. Hope you manage to get the right damping happening after all that hard work.
Click to expand...

Thank you, no I didn't re-hardchrome the shafts, they are original, if they had been in worse condition I would have change them with a complete kit that Wolfang has, including the shafts... I don't know anybody in Spain doing hardchrome, only in UK, so is usually never worthy.

Thank you regards,
Miguel
 
tom3c75 said:
Nice work Miguel.
The rebound damping on my Ceriani rears is also very stiff. 
Was like that with the original shocks, and also after I rebuilt them.
I seem to recall that I used 100ml of fluid.

Tom
Click to expand...

Great! good to know!
Thanks,
regards,

Miguel
 
Nice work restoring the shocks. I had a couple pairs of Ceriani shocks wit badly rusted shafts, quoted I got for hard plating was excessive so I found some hard stainless steel rod and cut to length then turned the threaded end stem on my lathe.



I made a jig to locate the original shaft top cap true and square and had a friend who is a professional welded tig the pieces together







Cost just a couple bucks at the steel supply shop. I don't recall the exact alloy but the dealer selected a stainless grade for its hardness.
 
Well done Canuck! it looks very nice job! I am confident using MIG, I regret I didn't buy a TIG machine, I think is optimum for that sort of jobs.

I am every time more convinced I have to buy a small turner.... but first I have to manage that my wife parks her car out of the garage... I am just half way to manage that! :LOL: :LOL:

Regards,
Miguel
 
that welding has to take a lot, and over time I fear for the safety of the joint, you cannot get a hard grade of S/S that is also easily weld able  especially when welded to mild steel, which should have been done with specialised filler wire or at least stainless filler wire, dissimilar metals is always the very hardest of welds to get strong.very nice job on the alignment jig.
CLEM
 
I'm tending to agree with Clem.

It's a bloody good idea to completely replace the shaft, I like it, but I would err towards a mechanical joint at the top, with maybe a steel socket of some sort being welded to the top eye-assembly, into which the new shaft could be fitted. (Having said that, there isn't room for much - the cherries use all the shaft travel when in full compression - using the rubber bump stop as a limiter).

Rebound damping loads and full-rebound (metal to metal in the shock with spring extention forces plus halting the downward wheel inertia) loads will provide the greatest challenge to the welds as they will be in tension then. Not huge in magnitude, but a bit of an arse-clencher if it broke.  :o
 
if the shaft broke, the shock on the other side would probably limit the amount of extension, with a bit of swing arm twist, but the  explosion might be enough to take the second shock very rapidly after the first, as in microseconds, as Haggis says an arse clincher, I had a shock bolt come off at Mallory one year at an ILOC test day, the handling felt funny and I stopped, , the left shock was attached only at the bottom, and the top was trying to do damage to the seat trims (1200TS) riding slowly to the end of the lap with a single shock was worrying, but doable, but had the shock exploded and released the tension, I think I might have had a very sore thigh, from either contact with it, or the ground.
CLEM
 
CLEMTOG said:
that welding has to take a lot, and over time I fear for the safety of the joint, you cannot get a hard grade of S/S that is also easily weld able  especially when welded to mild steel, which should have been done with specialised filler wire or at least stainless filler wire, dissimilar metals is always the very hardest of welds to get strong.very nice job on the alignment jig.
CLEM
Click to expand...

My friend has been welding stainless, cast iron, you name it for forty years, he works in the oil field maintenance industry and works in refineries. I trust his welding, he preheats components in an oven when necessary, scrupulously cleans components etc. He also repairs hydraulic cylinders and rams, no simple task. The welding was done with a stainless steel filler rod, like I said this is not his first rodeo. One of his specialties is repairing broken alloy engine cases and reattaching / rebuilding broken fins off heads and cylinders, what he can achieve with cast iron is amazing.
 
Canuck750 said:
My friend has been welding stainless, cast iron, you name it for forty years, he works in the oil field maintenance industry and works in refineries. I trust his welding, he preheats components in an oven when necessary, scrupulously cleans components etc. He also repairs hydraulic cylinders and rams, no simple task. The welding was done with a stainless steel filler rod, like I said this is not his first rodeo. One of his specialties is repairing broken alloy engine cases and reattaching / rebuilding broken fins off heads and cylinders, what he can achieve with cast iron is amazing.
Click to expand...

What a pitty that your friend is not living in Mallorca! :LOL: I would be a good client of him...
Miguel
 
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