harleyKmodel

Hi All,
My wet clutch on my 68CH feels like it is slipping a bit when I crank it. A friend commented to me that synthetic oils can cause this because of their cleaning additives? Is there some truth to this or is it just legend?
Thanks,
JerryR

It really depends on what type of synthetic oil and what type of clutch plates.

There's a little truth to the legend, but it has more to do with worn, original plates.

Old school oil is what I like. Still use 60 or 70 revtech off my shelf. Lighter oils, synthetic or not, could contribute to slipping if all adjustments are right. BUT regardless of weight and type its the friction modifiers added in the oil blend that allow slippage, even with Kevlar K wet plates. About the worst, is my favorite conventional oil #CastrolGTX. There 10-30 held viscosity at 600psi. They quit testing. I always ran their conventional 20-50 and never lost a lower end in 36 years of racing. And I built everything. But, the great GTX conventional makes my #Honda #XR544 clutch slip. Too slippery!! Erik

JerrryR wrote:Hi All,
My wet clutch on my 68CH feels like it is slipping a bit when I crank it. A friend commented to me that synthetic oils can cause this because of their cleaning additives? Is there some truth to this or is it just legend?
Thanks,
JerryR

It primarily depends on which synthetic oil you use. Most motorcycle-specific synthetic, mineral oils, of blends thereof contain no friction modifiers and are therefore suitable for wet clutch applications. Oils suitable for wet clutch operation will have JASO-MA, JASO-MA1, or JASO-MA2 designations indicating they are free of friction modifiers. For example, all the Amsoil full synthetic oils contain no friction modifiers, have the requisite JASO designation(s) and are suitable for motorcycle wet clutch use.

On the opposite side of the coin, there are many synthetic automotive oils that do contain friction modifiers (these won't meet the JASO requirements) and will cause clutch slippage. Such oils are obviously not suitable for motorcycle wet clutch use.

The excerpt below is from Barnett's website and regards appropriate oils for use with their wet clutch plates. Especially interesting are the comments about ATF and how the clutch function differs depending on whether you use Ford's type F (higher friction) or GM's Dexron (lower friction) ATF.

Hi Jerry,

Never had a 68 Sporty but I'm pretty certain that like the older ones, it cranks via the ratchet on the back of the clutch hub. That means the clutch plates play no part at all. Impossible to have slippage when cranking. Don't feel bad, even Harley had in wrong in the early handbooks saying a clutch that doesn't slip when cranking should be good on the road.

If I'm wrong on this, someone will put me right!

John

I'm thinking Jerry means "Cranking it on" High gear roll on's is where clutch slip first dhows up.

But your right about the clutch not playing a start in starting.

Running with oil that has friction modifiers will cause a problem with the plates.
In the old days we would drop th plates into a pan and cover them with a bit of gasoline. (Do this outside !)
Put a match to it. Thr oil in the plates will eventually burn off and you can clean and reuse the plates.
I wouldn't do that these days as I now know how to stop the clutch from slipping in the first place.
I\m not sure if doing this will burn off the friction modifiers though. We only used it on mineral oil saturated plates.

If you want to run it wet: Alto Red fibers, big twin clutch springs(shorter) with a 5/16" SAE washer in the bottom of cup. Any oil, but I run H-D 50wt, or Bel-Ray Gear Saver 75W or 85W. Set tension nuts so you can (with hard force) turn your pressure plate by hand when pulling clutch lever(disengaging). It works for me. Doesn't drag or pull, easy to get in neutral - and won't slip in high gear. Leave the cover off. Soak plates a bit before installing . . . Go for a ride - then drink a cold Red Dog !

When all said and done I found that if you pull in clutch lever and hold it there and turn clutch outer plate and check for wobble and if there is re adjust to remove wobble your clutch will respond better to neutral. By turning certain nuts in one half turn will correct this. Very tedious to do but worth the time. Only turn one half further on any one nut and don't back off any or turn more than a half turn on any. Don't loose count on any one - again very tedious you don want to over tighten just correct the wobble best you can. This method I found out to be better for clutch operation.