What is the unit of "position spring" and "position damper" in configurable joint?

Currently, I am implementing an application that renders real-like physics interaction in VR. But I am unsure whether the units that I am using for the configurable joint are correct.

I assumed,

1. the unit of "linear position spring" : N/m

2. the unit of "linear position damper" : N*sec/m

3. the unit of "angular position spring" : Nm/rad

4. the unit of "angular position damper" Nm*sec/rad

Until now, I used the units written above, and it seemed okay.

But today, I found that it does not show a realistic response at all. For example, even though I set the spring and damper values to be a critical damping condition, the object always overshoots. I think this is because of the use of faulty units or the limitation of unity physics itself.

Is there anyone who knows the exact units that unity physics uses for the spring simulation?