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How Many Plates?


robbiesty175
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Pulled the clutch cover off my Rotax 240 motor (tucked into an Armstrong/Can-Am frame, so thanks for allowing me into the SWM family!) due to the clutch sticking, even after warm.  The prior owner ran some pretty thick gear oil, and the motor sat many years unloved.  I prefer ATF, but things are still sticky.

 

Discovered five friction plates and six steel plates.  Should there be another friction plate? 

 

I am in the process of cleaning off the gaps in the plates, as I found some good material on this procedure elsewhere.  I've attached the pdf.

 

Appreciate any and all help.  Thanks!

 

 

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Clutch_Fix-1.pdf

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Hi, there are so many different permutations and who know's what's been tried with your clutch ?

Normally there are six of each. The stack height is usually around 32mm. The outer plain plate is usually 0,5 to 1 mm thicker than the others.

With time,  the standard friction material swells up apparently, thus causing the drag. The fact that the clutch usually drags when cold even with new plates seems to say it has not really much to do with the age of the plates themselves.

The clutch action is for most people a little heavy in action. Not really a problem if you ride classic nonstop and clutchless.

I have a set of sintered plates in my 125. They are made by Surflex in Italy. I wanted to put the same in my 320 but I have not been able to find any off shelf. Surflex will be producing again in October/November thy say.

Sintered plates soak up no oil, clutch separation is 100% even when ice cold. As good as no wear and therefore the same bitepoint day in day out. Standard springs, no slip in any of the higher gears, Magura lever, Venhill cable, clutcharm lengthened by 10mm, wetcluch 75w oil and the clutch is also pretty light.

I've put Barnett Engineering Kevlar frictionplates in the 320. Also made some clutch mods documented elswhere. Same lever/cable and Rockoil gearbox oil this time.

Still rebuilding the bike so I can't say how that combination works......soon hopefully.

 

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Found a free hour of time, so decided to clean up everything and pout it back together dry, just to make sure it all fits properly again.  Tried leaving two springs off and WOW what a difference!  Single-finger clutch action, and would love to see if this works.  Thinking about tightening up everything, Type F AFT and then give it a go.  Worse case is drain, tear apart and put back everything like it was.  Already seems improved, with the cleaner plates. 

 

UPDATE:  Cleaned, polished and cleaned again EVERYTHING!  Spent about 30 minutes fine tuning the clutch adjustment.  Added 1200cc of Type F ATF and or course the bike cranked up on the first kick.  Pulled in the clutch (with ONE-FINGER!!!) and it didn't lurch, budge or move forward at all.  Just a nice "click!"  Everything seems nice and smooth.  It went on the road through all six gears with seemingly no issues.  Pulls me up the hills in the yard with ease.  Pull the clutch in (which you LOVE to do, now that it's so light" and the bike rolls just like it should.

 

Found the previous owner upgraded the clutch arm and lengthened it too!  Plus an improvement with the larger balls.  Always an improvement!!!

 

Love my bike and can't wait to try it out for a nice day of riding.  Appreciate all the advice and support!

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Edited by robbiesty175
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Hi to all from Italy;

it is very important that the plates total thickness is near 27.5 mm .... the thickness of the plates new is 3.5+1+3.5+1+3.5+1+3.5+1+3.5+1+3.5+1.5=27.5 mm, this is very important for the springs preload, if this spring preload is reduced due to the plates wear the clutch slide for sure;

about the command, I use the original little balls (in teory a point of contact of a ball is independently of the ball diameter....) the original command with 10 mm longer lever and I remove the external ring that slide to the magnesium and I add a device in the same center of the adjust bolt ingaging the external of the thrust bearing to mantain centered the command....

normally I use 3 standard springs and 3 softer springs, the result is: no clutch slide and soft command.

Regards.

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Hi to all again....

to get a softer command is also possible increase the clutch rotation speed (as done in the climber....) in order to reduce the clutch torque and therefore reduce the preload of springs....but the torque reduced in the clutch appen again in the final transmission (mantaining the total reduction ratio....) with higher swinging arm reaction....

regads.

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