Sloppy HingeJoints

I am making a robotics game, and I need to be able to attach different types of objects to motors including wheels, weapons and extenders with varying colliders. Because of the varying colliders, I cannot use WheelCollider. Whenever I try to use HingeJoint or ConfigurableJoint I end up with the sloppiest results. Wheels are dangling far below their attachment point and they don't even keep the chassis from hitting the ground. Here's an example picture: ![robot][1]

The wheels in this picture all contain a ConfigurableJoint which I applied with this script:

 ConfigurableJoint confJoint = grandChild.gameObject.AddComponent("ConfigurableJoint") as ConfigurableJoint;
 confJoint.connectedBody = transform.root.rigidbody;
 confJoint.xMotion = ConfigurableJointMotion.Locked;
 confJoint.yMotion = ConfigurableJointMotion.Locked;
 confJoint.zMotion = ConfigurableJointMotion.Locked;

The code is properly executed so I guess you don't need the rest of the script. [1]: /storage/temp/19000-bot_example.png