let's just think about this ...

[bonnie john]

my hd clutch is bathed in oil up to the height of the outer circumference of the plates at their lowest point (manufacturer's spec)

a clutch by nature will centrifuge off any oil that dares to get near it while it's running

when it's not running, the clutch is tightly engaged or compressed. some oil might capillary into it, i'm betting about a glass pin-head full

so how do clutches slip when using FM oils?

i just can't seem to get my head around this one

 

[bepperb]

Your theory is that no oil actually touches the clutch plate or flywheel surface, so it doesn't matter what oil you use?

If that's your thought, why use any oil at all?

 

[Jim 5]

The clutch basket is further outside the circumference of your clutch plates and looks like a hamster wheel with thick exterior ridges. My guess is that the basket is going to splash oil all over the place even if you're right about the oil level relative to the plates.

 

[bonnie john]

that's a strange reply

the oil is there to lube the centre bearing of the clutch hub on the mainshaft, and to lube and cool the primary chain and drive

and yes, you could run no oil if you went to a belt drive with a sealed bearing. this conversion is well documented

 

[dsmith41]

Sorry, what is an FM oil? What does FM stand for?

 

[bonnie john]

hi ds

i'm using it the context of FRICTION-MODIFIED

hth, johnny

 

[Jim 5]

Originally Posted By: bonnie john
that's a strange reply

the oil is there to lube the centre bearing of the clutch hub on the mainshaft, and to lube and cool the primary chain and drive

and yes, you could run no oil if you went to a belt drive with a sealed bearing. this conversion is well documented


The fact that neither of us knows what the other means probably is indicative of my assumption that HD clutches work and look the same as a typical japanese/german/italian/english shared sump set-up with wet clutch plates inside an aluminum carrier basket. I've never had or seen an HD clutch opened up so this could explain things.

 

[ccdhowell]

I imagine that the clutch fibers absorb the oil to a degree when the bike is not running. I know that you must soak new clutch plates in oil overnight before you install them or they will wear out quickly. I imagine there is some interaction between the soaked plates and the characteristics of the oil. A friction modified oil would impart those properties to the plates when it is absorbed into them. I agree that it would be hard to imagine clutch plates on a running engine bathed in oil, but the oil is present...absorbed into the plates. That's my take on it, don't have a clue if I'm correct or not, but someone will correct me if I'm not, no doubt.

 

[Silk]

I bet if you pulled your clutch apart you will find oil on the plates.

Do it now and show us the photos....

 

[bonnie john]

110,000 k's and still running strong silk

i aint pulling nothing to bits till it's broke

as an aside, i owned a commando as a kiwi youth many years ago. you had to dismantle and clean the clutch quite frequently as the plates STUCK together and wouldn't free up or "slip" when you tried to free the clutch as you went to kickstart the beast

 

[Silk]

After years of running BSA's and Triumph's with leaky primary chaincases,when I got my first Norton (1962 99,600cc),I'd fill the chaincase,and then give it an extra glug to allow for leakage.But the Norton chaincase didn't leak...and I got clutch breakaway at 95 mph in top gear.Didn't slip at any other speeds or gears,just 95 in top.It was hard to talk myself into putting in the exact amount of oil,it just didn't seem right.

 

[PT1]

Oil lubes the bearings, chain and cools the clutch plates. You have to soak new plates in oil at least 2 hours before rebuilding a HD wet clutch. FM oils can leave additive deposits on the plates that causes them to slip. Very rare but it can happen.