Ceriani fork differences between Laverda & Ducati

B

Basketcase

Senior member
SF2

Well I installed Ducati 580mm fork tubes expecting to pull 10mm through the top triple which would still clear my handlebars.

However, I also installed Ducati damper rods because they are much better quality hardened and ground. The Laverda damper rods were soft steel (not the bushes !!) and the circlip grooves a bit shallow which tend to jump out.

However, the Ducati rods were 10mm longer. This means the forks on full extension are a further 10mm longer.

So now I have 20mm of the tubes pulled through the top triple to make the centre stand height correct. But now I can't fit my Raask bars ... FFFFFFF.

Options:

1.  Weld a bit to the centre stand feet. I used progressive rate springs so the bike sinks a bit more than usual off the stand for correct steering.

2. Install a 10mm spacer under the damper rod cup to limit extension. (Maybe above the valves without blocking the oil holes).

3. Shorten the damper rods on the lathe.

4. Install Ducati Ceriani flat top triple clamps with 610mm tubes pulled way through and use clipons clamped above the top triple. Problem is the the Ducati triple clamp offset is smaller and parallel with the steering head changing steering geometry.


 
Option 3 sounds like the easiest and quickest. Take it off the bottom end and then tap the thread in another 10mm.

You forgot option 5 - rake out the steering head and turn it into a chopper  :D
 
Dellortoman said:
Option 3 sounds like the easiest and quickest. Take it off the bottom end and then tap the thread in another 10mm.

You forgot option 5 - rake out the steering head and turn it into a chopper  :D
Click to expand...

Wouldn?t option 3 mean drilling in 15mm before tapping an extra 10mm.
 
Dellortoman said:
Option 3 sounds like the easiest and quickest. Take it off the bottom end and then tap the thread in another 10mm.

You forgot option 5 - rake out the steering head and turn it into a chopper  :D
Click to expand...

I got a complete Ducati Ceriani front end off a Harley !!!

Apparently a company in Perth (Australia) used to do conversions.
 
chrisk said:
Wouldn?t option 3 mean drilling in 15mm before tapping an extra 10mm.
Click to expand...

No, the damper rod already has a hole up through the middle.

However, you raise an interesting point. I dunno whether the ID of the tube is OK to simply run a tap further in. Something in a rarely used corner of my memory tells me that the rod ID is 10mm, but the bottom bolt is M8. So the threaded bottom end of the rod might be smaller ID than the rest. I could easily be wrong abut both the rod ID and the bolt size, but it would pay to check before chopping it off.
 
What about geometry adjustable clip-ones and mounting them on the tubes above the triple clamp?
Cheers
Jason
 
Or revert to standard Laverda forks as the perceived quality improvement is offset by the other stuff you mention.
 
Lee87H said:
I love the Ceriani that came on my SF2, very happy with their performance,
Click to expand...

Fine except that I need new tubes and springs.

These Ducati 580mm tubes, springs & dampers effectively cost me nothing.

Fit to Laverda sliders and saves a bit of money ... but adds a pile of nuisance.
 
Dellortoman said:
No, the damper rod already has a hole up through the middle.

However, you raise an interesting point. I dunno whether the ID of the tube is OK to simply run a tap further in. Something in a rarely used corner of my memory tells me that the rod ID is 10mm, but the bottom bolt is M8. So the threaded bottom end of the rod might be smaller ID than the rest. I could easily be wrong abut both the rod ID and the bolt size, but it would pay to check before chopping it off.
Click to expand...

And something tells me there is a brazed insert at the bottom of said tube...

piet
 
Sounds like 10mm long alloy bushes on top of the valves.

Below the buffer springs and with enough ID clearance for oil flow through valves and past the damper rods.
 
That sounds like the best option with the spacers.
An interesting point re the Lav damper rods being mild steel. I seem to remember mine were hard to drill when I fitted emulators, so I guess they were not mild steel.
As far as fitting flat Ducati triple clamps, I had these on my street bike  with standard rims (Jota clamps also have the same offset as the Ducati ones I used), albeit with considerably longer rear shocks and I found it steered perfectly neutral and stable. I was used to the kicked back Lav clamps but never found them neutral steering, which is my preference. I have the same with my 17" rims now and they are great on that too. However the standard headlight mounts won?t fit properly.
Also the different Ducati models had different length damper rods in their Cerianis if I recall correctly.
 
sfcpiet said:
And something tells me there is a brazed insert at the bottom of said tube...

piet
Click to expand...

I was just about to point that out ...... you can't just cut off the tube and retap.

I am in the process of reconditioning a set of Ceriani's off a Ducati 860 GT as well as the forks from my SFC. I measured the differences between the two ...... I suspect that these 860GT forks are different than the forks you have.

                    Laverda SFC        Ducati 860 GT

Damper rod      235 mm                215 mm
Fork tubes        570 mm                610 mm
Spring length    480 mm                520 mm

The damper rods are identical except for the length. They both seem to be good quality hardened steel.The piston on the Ducati damper rods is a softer material than the SFC pistons.

Just looked again ..... on mine you would not be able to get away with shortening the rod unless you could add a new threaded insert. It looks to be maybe 15 mm deep only.
 
if you want less travel or a shorter fork just put a spacer under the top out spring and shorten the spacer on top of the fork spring by the same amount .

Eldert
 
Eldert said:
if you want less travel or a shorter fork just put a spacer under the top out spring and shorten the spacer on top of the fork spring by the same amount .

Eldert
Click to expand...

I can't imagine wanting less travel ...... seems to me if you want the correct length fork ..... you use the correct parts or manufacture the correct parts. Everything else is a compromise.
 
I have new old stock 580mm Ducati tubes that cost me nothing so its worth trying to compromise.

The Ducati damper rods are much better material than my Laverda ones but 10mm longer so a spacer would limit fork travel to the same as my SF2.

Then only 10mm will protrude above the top triple clamp and I can still use my existing handlebars and the centre stand works OK.

 
Just curious ..... what length are the damper rods? My SFC forks have a 235 mm damper rod and the Ducati forks I took apart have 215 mm rods. Curious as to why the difference in metal quality as well.

Glad you have a plan without having to butcher anything.
 
Hi Jim,

The damper rods are in the bike at the moment so I can't get at them. I think the Ducati front end was originally a 750 since it used 580mm tubes and flat top triple clamp.

I will measure the old Laverda damper rods at the weekend. I think they came from a triple since they had 595mm tubes with Lav sliders. Those damper rods are made of soft low tensile steel with the cap welded in as opposed to Ducati high tensile hardened with brazed in cap.
 
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