How to rotate one object relative to another with a scalar

Hello, I am trying to create a steering wheel of a boat that when it gets rotated around the z-axis, it will rotate the rudder of the boat by the same amount divided by x. The problem is right now when I divide the z value by 4.5, the rudder will indeed turn slower as intended, but if I turn the steering wheel counter-clockwise from 1 degree to 359 degrees, the position of the rudder will jump to a different location presumably because I am using division. If I instead use multiplication of 8, it works fine for instance.

(never posted here before, so please let me know if you need more info - thanks :) )

Code:

             Vector3 eulerRotation = new Vector3(rudder.transform.localRotation.eulerAngles.x, steeringWheel.transform.localRotation.eulerAngles.z / 4.5f, rudder.transform.localRotation.eulerAngles.z);
             rudder.transform.localRotation = Quaternion.Euler(eulerRotation);