Harsh Cer Forks.

+1

Well having thought I'd cracked it yesterday, today I take the bike out and it was like riding a different machine - not a better one. Spent another hour up and down the coast with nothing particularly positive to report, just the same but different.

Need to do some more homework, there must be a way of making this work.
 
"forks as harsh as all crap." That sounds pretty much like sports suspension from the ?70s as fitted to Lav and Duc.
You are dead right Davo that getting the originals set up properly and working as well as they can is satisfactory. My own experience showed that replacing worn rebound valves (the stepped washer, I spun new ones up on the lathe that sat well into the damper rod) made them very good. However you still have both rebound and compression together reliant on oil viscosity. The emulators allowing these to be independent allows also all the possibiities to get it wrong. As this thread shows, playing with suspension can be like mud wrestling. Chasing "handling" problems is just as fraught as tuning problems. This thread is great for us who do want to play the game to set a benchmark. I have had them in my road SF for quite a few years and reckon they are great, the roads here in Norway have lots of big step bumps from water under the road freezing and expanding in winter and with emulators the forks cope much better with them. A bit of kickback from small sharp bumps is the only issue for me, and if fitting the lighter springs fixes it then I?m happy.
For me the big issue with these forks is stiction as they don?t have teflon guides.
 
This thread prompted me to go back to the box to check the spring rate.

Now here's a (potentially) stupid question, from the instructions I found on the box.

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To fit my springs I just opened the shock by taking off the cap and put the new spring in.

Also 100% sure I was told to put the spring in with the tightly wound section at the top. The instructions above say put that at the bottom. (Unless the instructions were written for upside down forks).

Anyway have I missed a trick here?
 
"(Unless the instructions were written for upside down forks)." I think you are confusing forks with shocks. The Ikon 7610 is a rear shock absorber with an external spring.
 
Davo, some sort of adapter is required to fit an emulator to the top of the damping rod. you can use any springs that fit.

Tippie, a neat trick with the ceriani is to fit the alloy bit, with the teflon ring, from the marzo fork, to the top of the damping rod
to reduce stiction. you could also machine a groove in an adapter to take a teflon ring. i suspect there is the suitable ring in use in an automatic gearbox somewhere for pennies. i'll see if i can find a pic.

Cam, in this part of the world the # denoted pounds not kilos. sorry for any confusion
 
The stiction I refer to is between the stanchion (downtube) and slider, but it is a good idea of yours for stiction between damper valve and stanchion.
 
jotacorsa said:
Davo, some sort of adapter is required to fit an emulator to the top of the damping rod. you can use any springs that fit.
Click to expand...

That is now the case but was not so when I originally bought the emulators for Ceriani forks. It was definitely not mentioned on the Racetech site and if you look at the Technical pages on Laverdamania to this day it still only mentions the need for adaptors for Marzocchi forks only. In fact, the first time I read anything about emulators came from this forum after Vince commented that he had found out about them from the Racetec technician at a meeting somewhere.

The original adaptors for the Marzo forks were to allow the emulator to seat properly on top of the damper rod, which was not required for the flat top of the Ceriani rod. The adaptors they now recommend for the Ceriani forks have a seal that stops fork fluid passing around the emulator and have nothing to do with the emulator seat on the rod - a completely different function.
 
That was Paul Thead, Mr Race Tech at Wakefield Park race track. We went to a track day to watch Crispin sort his Space Frame and Paul was in the next pit, he comes to OZ ever year to do Suspension Seminars. It was hard to follow we he was on about but it involved a Teflon seal that forced all the oil through and not past the emulator.
At the time, maybe 5 years ago they had a bit made to do this for 40mm Husky forks. I never did get any info direct from Race Tech USA from my emails but the local bloke in Sydney did something for me. On mine its something below the emulator that this seal was fitted to and I haven't seen it since it was fitted?
 
Here is a (bad) picture of an adaptor (required for Ceriani forks) I made machined with a Teflon ring.

Cheers,
St?phane
 

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I finally got a chance to try the fork out and it's very very nice, firm but no discernable shocks coming through the bars. Will try it out on a longer faster test at some point soon.
 
After last weekend long day ride that included a great bike road, 30k or so of not so smooth dirt farm tracks and an hour of slow traffic splitting I am much happier with the Cer fork on my 3C. Firm but nice and compliant.

So I now tried the same setting on the 38mm Maz fork on my Pantah expecting similar results. It's way worse.
I have a pair of Maz Symbols shocks on the rear that I wasted some money on having rebuilt and wasn't so happy with the result so I borrowed a pair of Koni shocks of Jason to try. The first lap of my test track and I noticed the horrible bouncing that happened with a closed throatal, causing almost a sea sick feeling was considerably reduced with the shock swop. I checked to see if I had an out of round wheel or tyre it was that bad before the shock swap. Seems I need new better working shocks. So then I checked the fork sag and travel used. The fork action is harsh and choppy, well worse than the Cer fork with the same settings in my 3C. Sag is close at 30mm but I am only using 80mm of fork travel on this bumpy test track. Where is the other 30 or 40mm of travel, don't know if total travel is 120mm but will check. I am thinking maybe the suspension expert may have over filled the oil and its hydraulic locking? So next job is a fork oil change and checks of the oil height. Going for 150mm springs and emulators out. Here we go again.



 
You are doing lots of good research for us Vince. You seem always to go for as much oil as possible, using the fully inserted slider method, with as small an air gap as possible. On conventional damper rod forks I have always used the method where I fill enough oil to ensure coverage of the valves. I fill the forks and pump enough that all air is out, and then make sure that I cover the top of the valves by about a cm of oil. If I quickly extend the slider it should not suck air, with emulators I use a rod to push down on the emulator so that it follows the damper rod. Using this method I have found that the amount of oil I add is the same as specified for virtually any bike. I then check the airgap by the compressed slider method and add a bit to one side if necessary so that they are the same.
It is just a suggestion as you have tried so much with these forks.
I remember production race teams used to fill as much oil as possible to overcome some of then soft spring clearance problems with Japanese bikes, and it is the way to do cartridge forks.   
 
Hi Tippie, do you remember what the distance was that you ended up at for air gap. I find it hard to believe mine have the oil level high enough to lose 40mm of fork travel but I don't see what else would do that? Couldn't be coil bound springs, the suspension bloke does know his stuff. Used him for years
 
My bikes are 750?s so different length downtubes.
I noted down 215mm from the oil to the top of the downtube fully compressed had the allen screw on the emulator just covered. Was 230ml of fork oil. It always was 200ml without emulators. One is a racebike and one is a road bike and both work as well as I can expect from  Cerianis. I just fitted the blue springs as suggested to the roadbike as it could have taken sharp steps a bit better but otherwise it was fantastic. I might fit the blues to the racer but I just added 10mm more preload as it was bottoming under brakes. Will see how both bikes go pretty soon when the weather allows here in arcticland.
It is easy enough for you to give it a try.
 
So I blow the fluid out of the 38mm Maz forks today, with zero fluid in them I still only get 80mm of travel so the restriction definitely isn't the fork Hydraulically Locking with too much fluid. I think from memory the springs are preloaded about 10 to 15mm so I doubt that also why I have so little travel. I will pull the springs tomorrow and find how much the forks can move with the caps and springs out, I expect that to be at least 110mm or a bit more.Don't know what's going on with this missing fork travel?
 
Caps off and springs out I get 130mm of fork movement with no restrictions. Spoke to the suspension guru and he said cannot be coil bound, to be honest, the main spring is too light for my weight but there the heaviest available and it has zero preload anyway. This makes no sense at all so it's going out to him to see why it's defying the laws of physics. I want my 50mm of missing travel and a more compliant fork.
 
Thought you bike had Ceriani's on it and that you had sorted it... way too much time on your hands Vince me thinks.
How did you get on with Roger did you make a date for the club ?
 
Haven't spoken to Roger yet, this is now the Maz forks on the Pantah. The Laverda Cer forks are way better now. Seems the Laverda emulators have had the stronger green, in my case no colour, springs, replaced them with the blue springs and it now nice and compliant. Unlike the 38mm Maz forks in the Pantah. Today I was thinking maybe I had the wrong wheel spacer fitted when my mate did the 35mm to 38mm fork swap 30 years ago but a trip to Gowys confirmed Its got the correct wheel spacer and that wasn't the cause of the binding issue.
 
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