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“Sir is that a Ducati?”

“Is there something wrong with your bike, why does it sound that way?”

“OMG that little things got a Dry Clutch?!?”

“LOL, I heard you coming from a block away and I could have sworn a monster was going to pull up”

“*Shaking head* I just don’t even know what to think of it. *Shaking head*”

“Man your bike makes a lot of click and chattering sound for something so small!”

And the hits keep coming. Its true, the dry clutch on the mini is something many people have a hard time wrapping their mind around.  Non mini moto enthusiasts think its down right insane that there is such a aftermarket add on for a bike that is some what a novelty to them. I gather that many of the custom mini community find them elusive, over priced,  a definite bragging point and possibly pointless. On the same point I’m sure there are a ton of people out there that think a Custom mini that is capable of 70+mph is also pointless. Who cares about pointlessness. The purpose of this little note is to shed some light on some of the pros and cons of the little clickty clack HP grabbers as well as talk about tips and fixes for some specific aspects of the Dry Clutch design.

Wet and Dry Defined

A ‘wet clutch’ is immersed in a cooling lubricating fluid,  A ‘dry clutch’, as the name implies, is not bathed in fluid. . - source > wikipedia.com

The Wet Clutch

Think smooth fluid action. For the most part a smooth fluid clutch serves us best. In my opinion the biggest  upside to the wet clutch is is cleanliness for the clutch itself. The fluid keeps the clutch plates clean and gives smoother performance and longer life. Wet clutches however, tend to lose some energy to the liquid. Since the surfaces of a wet clutch can be slippery (as with a motorcycle clutch bathed in transmission oil), stacking multiple clutch disks can compensate for the lower coefficient of friction and so eliminate slippage when fully engaged.

Wet clutches, since they use some form of internal lubrication, are also prone to slippage with the wrong oil.  Motor oils with added friction modifiers can induce unneeded slippage.  Most oils with a viscosity rating of 10W-40 and above don’t have those friction modifiers, but I wouldn’t bet that’s universally true.  Many motorcycle specific oils often have a JASO MA rating which means they’ve been tested to be safe tor wet clutches.

Wet clutches can also sometimes get sticky as the oil develops a viscous bond between the steel and fiber covered plates. This often results in a “clunk” when engaging first gear, particularly when the lube is thick as when cold.

The Dry Clutch

Many motorcycle racing designs such as many of the engines that are used in Moto GP use a Dry Clutch design for ease of maintenance as well as performance. On either of the designs I have worked with both Takegawa and Daytona I can attest to this.  I can have had the clutch pack out and back in the bike in under 15 min. I’ve even done this in the middle of a ride at a stop to investigate some other issues.

Dry clutches typically have a more narrow “slip” range.  It seems that the range from zero transfer of power to full lock transfer of power happens much more quickly than wet clutches. Thus, slipping the dry clutch during very slow speed maneuvers could get a little dicey.  The bike can tend to lurch forward as the last bit of clutch locked up. The clutch feel when not properly maintained will not be a linear engagement.  If you have ever driven a farm tractor you will have a sense of what that clutch surge would be like. Grabby is how I refer to it. I would imagine with a Inner rotor, or a lightened flywheel installed it would be very easy to stall out the motor if you were not on the gas enough.

Noise its in the ears of the beholder. As far as mini bike dry clutches that I have heard the Takegawa is pretty tame sounding where as a Daytona is obnoxiously loud. Fired up next to a Ducucati with a aftermarket open cover its hard to say which is louder.

Honk, Squeak, Chirp, Squawk when slipping

To me this is the Achilles heal of the dry clutch and just a bigger reason then any for me to say that the wet design is far better for a mini then the dry. Often what happens is wear debris get on the steel plates and causes them to engage unevenly there by you get some of the terrific squaking notes. Also what can happen over time is you get a general build up of glazing from the friction plate material on the steal plates, this can also cause the added squeaking nuisance.

Going back to the Daytona these screatching, chirp noises showed up almost right away and for a while I thought there was nothing I could do about it, perhaps just a issue with the design. The action on the clutch was also very poor, it grabbed so darn quick it made it almost useless for a street application. I tried to contact a few of the guys in Europe that I knew were running the same or similar clutches. People running the Takegawa versions were not seeing the same issues as I was or maybe they just didn’t want to say that their precious clutches had any issues. I did find a few guys running the Daytona dry clutches and all of them mentioned that they were having the same issues as I. None of them had any suggestions as to a fix.

One friend of mine was able to offer a suggestion. Liam Shubert who at the time was working on the Pracmic Moto GP team told me of a product that they use on the Duacti GP bike dry clutches called Molykote D-321R. Which is a spray on dry anti friction coating much like anti sease. He said to pull the friction and steel plates out and give them a good once over and  I would be good to go.

Molykote worked wonders. All the gripes and issues I saw went right out the window. After the first time I applied it the action was smooth, no chirping, and still grabbed like nothing else. I have since now only had to reapply it once in the last year and this last time I also cleaned the steel plates of any glaze by using a little brake cleaner and a scotch bright pad which is a tip i got off some Ducati forum. On my other bike that has the Takegawa dry clutch I eventually did notice some chirping sound and used it on that clutch as well.

To apply Molykote to a dry clutch remove the plates from the basket and hang them up in the garage. For sparying  give the plates, both the friction and the steel a twice around with the spray can and let them all fully dry in the sun before reassembling the clutch. That’s it. My only other tip would be to be careful with the pressure plate. Make sure to loosen it evenly in a crossing pattern a little on each bolt at a time. If you loosen all the way on one and non of the others or three and save the forth for last you risk breaking it by having all the spring pressure being held at one small point. I haven’t seen one brake on a Takegawa or Daytona unit but I have seen a pressure plate on a Honda NICE 110 clutch break in this manner.

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