Balancing Forces + Gravity

I am having problem coding basic suspension i think i have Physics problem don't know how to approach it. I am trying to suspend a box in air using physics i think i am doing something wrong would like a new set of eyes

 using UnityEngine;
 using System.Collections;
 
 public class Suspenzija : MonoBehaviour {
 
     public float SuspensionRayLength;
     public float SuspensionPower;
     public Rigidbody kart;
 
     // Use this for initialization
     void Start () {
     
     }
     
     // Update is called once per frame
     void Update () {
     
     }
 
     void FixedUpdate ()
     {
         //Defining position,  bottom midle of Box 
         Vector3 midlebottom = transform.TransformPoint (new Vector3 (0f, -0.5f, 0f));
 
         //SuspensionRay hitColector and executes ray for difined point
         RaycastHit WhatRayHited;
         if (Physics.Raycast (midlebottom, -transform.up, out WhatRayHited, SuspensionRayLength)) 
             {
             //Compresion Calculation
             float RCompressionRatio = WhatRayHited.distance / SuspensionRayLength;
             //Reversing it for using it as power multiplayer cuz multplaying it with 0.* is /
             float CompressionRatio = 1 - RCompressionRatio;
             //Clamp just to be sure xD
             Mathf.Clamp (CompressionRatio ,0f ,1f);
 
             //Adding Force to counter gravity so Box goes Up
             kart.AddForceAtPosition (Vector3.up * CompressionRatio * SuspensionPower, midlebottom, ForceMode.Impulse);
 
             //Waz geting jumping box like trambolin so i diceded to add counter force so if suspension almost 
             //extended i add force down, hoping for the best but not good solution, NEED HELP
 
             //MY idea for stoping box jumping all time Not WOrking ATM
             if  (CompressionRatio < 0.8f)
             {
                 float  AntiCompressionRatio = 1f * CompressionRatio;
                 //Tryed adding first pure counter force but it dident work so i tryed to kinda limit it 
                 //with math.clamp but still not geting stable suspension MY MAIN ISUE
                 Mathf.Clamp(AntiCompressionRatio,0.1f,0.6f);
                 {
                 kart.AddForceAtPosition (-Vector3.up * AntiCompressionRatio * SuspensionPower, midlebottom,ForceMode.Impulse);
                 }
             }
 
 
             //Green Ray for debuging
             Debug.DrawRay (midlebottom, -Vector3.up, Color.green);
             Debug.Log (WhatRayHited.distance + "Distanca of hit Amortizera");
             Debug.Log (CompressionRatio + "Power of Amortizera");
 
             } 
         else 
             {
             //Red Ray for debugign
             Debug.DrawRay (midlebottom, -Vector3.up * SuspensionPower, Color.red);
             }
     }
 }