Ceriani 35mm fork springs manufacturer and/or shop

hooksey said:
Makes even more sense, with the value of our $ against the euro  ::)
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Thanks Hooksey,

DAM Classic Racing has indeed a great offer, but shipping from Australia to Belgium is costly.
Parcel total value + shipping cost + import cost.

Cheers,
Matt
 
Matt888 said:
Many thanks Ernesto & Stephane!

I must admit I'm a bit confused now:

Wirth 480mm
Wirth 500mm
Race Tech 425mm x 26mm 0.80kg
Race Tech 425mm x 26mm 0.85kg

3 different lengths, which one to choose?
I guess I could take out the original ones, measure them and replace by the same length?

Could anyone enlighten me on the differences to expect using different spring lenghts?

Mainly road usage, Ceriani fork with drum brakes (no discs).

Many thanks,
Matt
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Many thanks Clem, Piranha & Paul,
All valuable inputs!


But I'm still trying to understand the 4 different lengths now... which one to choose?
Wirth 480mm
Wirth 500mm
Race Tech 425mm x 26mm 0.80-0.95kg
Dam Classic 476mm 0.65-0.9kg



I found an interesting article on the Race Tech website:

SPRINGS - LONG vs. SHORT
2-1-500.jpg


Many of our customers have questioned us on why our fork springs are so short, particularly on vintage applications. Here's the long (or short) answer.

In the past the material that manufacturers used to make springs was pretty poor. This meant springs would not only often sack-out but it also meant that fairly heavy gauge wire needed to be used. The heavier gauge the wire the less stressed it is at maximum travel. But this also means that the spring designs were pretty heavy (they weighed a lot) for a given rate.

Let me back up here for a moment. Springs can be made with a variety of wire gauges or diameters. The larger diameter the wire, the more number of coils are required for the desired rate. Thinner wire could also be used requiring less number of coils. I explain this in much greater detail in "Race Tech's Motorcycle Suspension Bible" if you're interested.

These two examples; thick wire, lots-o-coils vs. thin wire, fewer coils introduces us to the concept of a Hi-Performance Spring. The thinner the wire the lighter the spring for a particular rate. These are Hi-Performance. This also requires better materials that weren't available back-in-the-day. In fact it is very rare (and pricey) even today (note: there are only two wire manufacturers in the world that can produce the quality of material we require for most RT Hi-Performance Fork Springs).

It may have crossed your mind that a spring design using thinner wire with less coils would have more travel for a given length than a spring made with thick wire. This means we can design our springs shorter and still have the required travel. This also means we will need to use longer spring spacers but they are generally much lighter than spring.

Using a shorter spring has the added benefit that it will fit in more bikes if we employ different length spacers. If we tried to chase all the original spring lengths we could never make enough of any one particular design to be economical.

So there it is folks. You're gonna have to cut some spacers. But really that is the only down-side. The up-side is less weight, more applications and super-tough hi-performance springs.




 
Matt, the length is not really that important - it is a secondary consideration. Initially you MUST worry about outside diameter of the spring. If you have standard road-going 35mm Cherries, the spring pocket in the top of the damper rod is diameter 23 and you may well have a stiffening sleeve inside the stanchion which is inside diameter of 25. You may find the race tech mentioned below do not even fit into your forks.
 
I would say the spring length plus spacer length have to add up to the required length (which I would think is the original (new) spring length plus spacer length).
Use shorter springs (within reason) and compensate by using longer spacers.
 
What you want is 10 to 15mm of spring compression and that includes the fork cap being screw down. Measure fork sag when that happens. Sag dimensions should be approx 1/3 travel. None of this has anything to do with the spring rate, this bit is ride hight. You do need something big enough and solid enough between the spring top and the spacer. I use a thicker than usual washer and the spacer is usually thick-walled poly pipe
 
Paul H said:
Matt, the length is not really that important - it is a secondary consideration. Initially you MUST worry about outside diameter of the spring. If you have standard road-going 35mm Cherries, the spring pocket in the top of the damper rod is diameter 23 and you may well have a stiffening sleeve inside the stanchion which is inside diameter of 25. You may find the race tech mentioned below do not even fit into your forks.
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Good to know these dimensions Paul, thanks!

I confirm I got standard road-going 35mm Cherries, all original inside (linear springs).

Cheers,
Matt
 
Vince said:
What you want is 10 to 15mm of spring compression and that includes the fork cap being screw down. Measure fork sag when that happens. Sag dimensions should be approx 1/3 travel. None of this has anything to do with the spring rate, this bit is ride hight. You do need something big enough and solid enough between the spring top and the spacer. I use a thicker than usual washer and the spacer is usually thick-walled poly pipe
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Thanks Grant & Vince,

Revue Moto Technique (French Technique Magazine) mentions a 105mm travel for a Ceriani 35mm fork with 170cm? oil (Shell Tellus 33 or 41).
The original Laverda Manual mentions 200cm? oil (Total Equivis 10).

Cheers,
Matt
 
200cm3 is for 38mm forks, pretty sure the 170 is correct for 35mm. Whatever, as long as the damper rod is covered by half an inch of oil after all the air is gone, fully extended, you have the required amount. I do this with 38mm Cerianis and it takes 200cm3 as the manual says. Oil weight these days is dependent on wear in the system, some require thicker oil, usually either 10 or 15wt.
 
Yep, I definitely recall 170cc for my SF1 with the 35 Ceris. And yes, pretty sure the staunchions were thinker-walled than 38s. Didn't know that was a 'strengthening sleeve', but makes sense. So just be sure you know your dimensions and confirm with your supplier.
 
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