The machine really just needed to be exercised a bit. After a few hours, the jerkiness has disappeared and everything is operating very smoothly. The steering clutches and brakes are very sensitive and positive in action. I didn't even have to "bleed" the hydraulic lines as they purged themselves during operation. Last week I resealed the angle and tilt cylinders and didn't even have to bleed them either.
Darin now has the tools I made to assemble the clutches so contact him for more information concerning their use.
For a relatively small dozer, this D21 is a pleasure to operate. I've been pushing dirt and clearing small trees, bamboo, and underbrush with ease. The joystick controls, to me, are more desirable than lever operation and less fatigue.
The utmost, main thing to consider on clutch overhaul is to positively seal all those bolt holes in the rear of the clutch housing to keep moisture and trash out. Also, new gaskets and seals will result in an air tight assembly.