Can't rotate a configurableJoint with angularVelocity in 5.3

I have a game in Unity 4.7 that uses many configurablejoints as motors. It no longer works in 5.3.
For example. I have a static cube (cube1) connected to another cube (cube2) along the X axis.
cube2 has a configurable joint attached to connectedbody cube1.

I set a targetAngularVelocity 10,0,0
RotationDriveMode XYandZ
In 4.7 it spins fine.

I can’t seem to duplicate this in 5.3.
I set the other parameters the same.
The cube will not rotate in 5.3
There is no jointDriveMode if I query it, it is set to “none” and it cannot be set.
How do I get the cube to rotate with a velocity in 5.3.

Make sure that you have a position damper value set in the drive.

If you check the docs for PhysX under the drive settings (Joints — NVIDIA PhysX SDK 3.4.0 Documentation) you’ll see the formula used to calculate force:

force = spring * (targetPosition - position) + damping * (targetVelocity - velocity)

So without a damping value the force will always be zero when using velocity only.