Have a John Deere 4640 quad that crushes hard when going into any gear and also jerks forward when you release the clutch pedal. Clutch rebuilt and adjusted with the jd tool had the same symptoms with the old clutch. The clutch valve has been checked, all springs and valves are operational. Any suggestions?
There is no friction surface on the John Deere 4640 QR flywheel to be repaired. Burn-in / discoloration will not harm the performance of the clutch as long as the surface is still smooth and flat.
The clutch needs to be very carefully adjusted with the best inch torque wrench you can afford. Let’s say you did it.
The most likely problem is an oil leak in the clutch piston oil circuit. The clutch valve modulates a small amount of coupling oil. It cannot compensate for a leaky piston seal. The most common cause is a very rough piston bore which causes wear on the seal. The surfaces on which the seal runs should be mirror smooth.
You may also have a leak elsewhere in the clutch housing.
Also, if the splines of the clutch hub are worn, the clutch will not function properly. How’s the remote, the sleeve?