Fork Oil Weight

V

Vince

Hero member
I am having a rethink on what fork oil I am using.I like a soft action and to use the full travel in my 3C.Thats Cerani 38mm forks fitted with Emulators,when I had the Race Tech blokes fit the Teflon bushes to the Emulators they wanted to use 15wt at 130mm.I didn't like that idea so we ended up at 7.5 wt but they said if it kicked hard off bumps then the oil was to light.Lately I have noticed it kicking plus some patter on corrugations so I am going to try the 15wt.I am usually found riding rough as guts back roads with all manner of big and little bumps.I have big bones,130kg plus.Whats the consensus out there in Laverda land re fork oil.I am looking for suspension that I don't notice a thing,comfort and traction even under brakes.Hoping that 15wt doesn't prove to harsh or slow ending up in packing,thats not reacting fast enough before the next bump.
 
My 81 jota front end is standard  and I have found 7.5 spot on. I put in 300 ml.
Not ure how this would translate to Ceriani 3C.
John
 
Vince,

I run 340ml of 15 weight on my 3C.     
It works for me and, at about 85 kg, I'm a bit lighter than you are.
Also, ambient temperatures are not very low in my part of the world.
However, this is with the standard Ceriani damping.
 
With emulators in Cerianis on my twin I have the recommended by Race-Tech 7.5wt, rebound is excellent but a bit too much compression, will back off the spring on the emulator if it annoys me too much. It kicks up a bit on sharp bumps, does not kick back from a bump. Remember that the emulator (compression damping) can adjust with shim/spring but rebound is the original valve unit and only oil weight alters it (unless you start experimenting with the valve). If the Race-Tech guys said 15wt you should try it, but make sure your rebound doesn?t get too strong, as you say not returning in time for the next bump.
 
interesting discussion. Noticed last time out on Monty (with the new springs) that it was bit soft in the front, but particularly in the cold morning. Running 10wt, emulators @ 30% out on the spring, with a new 420mm spring, and to compensate, 20mm longer than previous pre-load spacer, to bring the spring to 400mm (as spec. standard). The longer the day went, the more stable it went. Now some of that may have been tyres, but we have an established regime and it's pretty reliable, track temp. etc... BUT

I'm trying to figure out whether to increase preload, say in 10mm stages, or whether the emulators are capable of taking that vague feeling out in cooler conditions. I may have answered my own question in thinking about this post... but I'm interested in other more experienced thoughts perhaps.. :D

Cheers in Racing

8)
 
Ian,its not that hard to make external preload adjusters from scratch.Buy a set of fork caps and drill and tap for 10mm bolts.Insert the bolts and double nut a big washer inside the cap.There are kits available to do this.They also make air pressure release buttons as well.Similar to the Schroeder tyre valves that used to be BAD IDEA used to pressures forks.With lots of action forks can build up air pressure that changes the last bit of travel.These buttons make relieving this pressure easy pesy.Having the forks pump up would make them harder,not your problem.
 
If you lack pre load on your front end,there is a good chance the front wheel will chatter when coming out of a bend  while on the power.Reason being the spring isn't being loaded up sufficiently.
If that's not happening then I'd take off a small amount of preload,to allow the spring to be compliant,and therefore give back some feeling to the front end.

Andy
 
Vince said:
Ian,its not that hard to make external preload adjusters from scratch.Buy a set of fork caps and drill and tap for 10mm bolts.Insert the bolts and double nut a big washer inside the cap.There are kits available to do this.They also make air pressure release buttons as well.Similar to the Schroeder tyre valves that used to be BAD IDEA used to pressures forks.With lots of action forks can build up air pressure that changes the last bit of travel.These buttons make relieving this pressure easy pesy.Having the forks pump up would make them harder,not your problem.
Click to expand...

Can you give us a link to the aforementioned kits?
 
beauchemin said:
Can you give us a link to the aforementioned kits?
Click to expand...

at least on the Mazocchi forks, when you look into the top of the fork cap down the hole, there is a screw with tapered edges. Under that screw is a hole drilled right through the fork cap. In that hole is a ball bearing and a spring. When the fork innards start to build pressure, the ball bearing lifts against the spring and relieves that pressure. So, original design feature. Not particularly weather tight. Don't know about Ceriani forks, as their caps are quite different.

next time anyone is servicing their Marzocchi forks, remove the small screw from the fork cap, clean out all the rust and gunk blocking the hole, clean up the ball bearing and spring, lightly lubricate, and away you go. I would be interested to know if Ceriani has the same overpressure release feature built in somewhere.

Paul LeClair
 
LaverdaIan said:
interesting discussion. Noticed last time out on Monty (with the new springs) that it was bit soft in the front, but particularly in the cold morning. The longer the day went, the more stable it went.
8)
Click to expand...

Maybe get some fork warmers made ups  :D
 
Paul LeClair said:
at least on the Mazocchi forks, when you look into the top of the fork cap down the hole, there is a screw with tapered edges. Under that screw is a hole drilled right through the fork cap. In that hole is a ball bearing and a spring. When the fork innards start to build pressure, the ball bearing lifts against the spring and relieves that pressure. So, original design feature. Not particularly weather tight. Don't know about Ceriani forks, as their caps are quite different.

next time anyone is servicing their Marzocchi forks, remove the small screw from the fork cap, clean out all the rust and gunk blocking the hole, clean up the ball bearing and spring, lightly lubricate, and away you go. I would be interested to know if Ceriani has the same overpressure release feature built in somewhere.

Paul LeClair
Click to expand...
Pulled the original screw, spring and ball out on my fork caps, drilled them out and araldited some schraeder valves in. Wanted to relieve the pressure in the forks so that the seals would have an easier life, bit like the crankcase relief valve on the engines preventing reducing oil leaks.
 
Well, that's news to me!  I've not seen the ball valve gadget in the fork caps. I have two bikes with Marzocchi forks. The Ducati has schrader valves in the fork caps. I don't pressurise the forks, although that was the original idea. I just use them to relieve pressure once in a while - only reliable way of getting them both equal without a balance pipe. The Laverda just has solid plugs, no ball valve.

Cam
 
My Marzocchi forks have the ball release valve.
As Paul said, when I do a fork oil change I make sure it is free to work.
John
 
My RGS Mazocchis definately had the pressure release mechanism, seemed pretty rudimentary so I whacked in some schreaders cut from old inner tubes; they dont keep the pressure in, they keep the pressure out. Seems to work.
 
Paul LeClair said:
at least on the Mazocchi forks, when you look into the top of the fork cap down the hole, there is a screw with tapered edges. Under that screw is a hole drilled right through the fork cap. In that hole is a ball bearing and a spring. When the fork innards start to build pressure, the ball bearing lifts against the spring and relieves that pressure.
I would be interested to know if Ceriani has the same overpressure release feature built in somewhere.
Click to expand...

Paul, my '73 3c with 35mm forks had that same silly damn rust trap that you describe, definitely Ceriani forks. I think when they went to the 38 mm forks Ceriani had seen the light and didn't bother to put the pressure relief mechanism in. Well, I don't remember seeing it in any 38mm Ceriani bikes.
Now let's see how many people have Cerianis with 38mm forks with pressure relief valves.

Ken
 
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