TY175 clutch mechanism vs DT175 clutch mechanism

[David Lahey]

While I was working on the clutch cam on my hot rod TY175 recently, I checked to see if there was a cam that was in better condition in a DT175A motor that was sitting around.
I found that the DT175 cam has the adjustment ramp in the opposite direction to the TY175 cam and wondered "why is this so"?
I still haven't worked out why they were made different. Both of them work fine in the TY175 motor.
Does anyone have any ideas?

[Kurt]

By reversing the ramp direction do you get a greater area of shaft to be in contact with the sidecase housing in the area where the load is being applied by the clutch push rod, therefore reducing wear?

[llewdaert]

One would tend to move down and one would tend to move up,as the load comes onto the ramp. Either case the load shifts toward the small end ,so no change there.

But the up and down movement may tend to load the seal with crud when it pulls down, or expose the shaft when moving up.

Overall moving up when loaded would be preferable in my opinion,as it stays in that position momentarily. So would not get dirty.

But moving down on application -the shaft may already be caked, and thereby damaging the seal and eventually causing ingress into the primary/clutch area, and wear on the rotary bearing surfaces..

Maybe.......