How much clutch hub movement?

I am getting a drumming noise right at 1800rpm on my 73 850. Nothing above or below that rpm.
This seems to be the point of maximum vibration, front wheel dancing, etc.
It feels like it was coming from the primary so I removed the outer cover and:

I can easily move the clutch basket a little bit in and out.
My suspicion is that maybe the hub nut needs to be tightened down again, with something to hold the hub from turning.

OR, maybe I am wrong, and the drumming vibration is not coming from the primary.

My questions: Am I correct in assuming that a properly set up clutch and basket should not be able to be moved by hand in
and out from anywhere on its circumfrance, even the little, by definite, that I can feel? Basket should be rock solid?

You should not be able to move the clutch chainwheel "in and out". A slight amount of "wobble" with the plates and spring removed is normal. I would check the circlip on the mainshaft that the clutch hub locates on. These can shear if the clutch hub nut is overtightened. Of course the obvious is the clutch hub bearing wear.

I finally shimmed the primary to eliminate the circlip altogether--the clutch center lands abut directly on the mainshaft grooves for a jam fit--no wobble, no worries about crushing the circlip with 80 lb-ft of torque--plus the whole rotating mass moves inboard 1 mm or so.


Tim Kraakevik
kraakevik@voyager.net
'72 Combat

Check the rear ISO. I've heard that noise before and it went after the rear ISO was replaced. The ISO had completely disintergrated into rubber dust, strangely the motor ran so smoothly. :?

Cash