Collision detection firing too late or too early

I'm trying to make a sticky grenade by disabling its rigidbody upon collision, using OnCollisionEnter(). However, OnCollisionEnter() fires when there is clearly no collision happening, as you can see in this image : https://imgur.com/w9KMEff. This causes my grenade to stick in the air. I suspect this is due to a lack of synchronization between physics loop & rendering loop. Also, my standard "non-sticky" grenade uses the same model & is working finely.

I already tried the following :

• Verify that there are no other colliders which could cause my grenade to "stick in the air"
  
  
• Use OnTriggerEnter() instead. The result is a little better but the problem is that it is fired too late, only once the grenade is inside an obstacle or an enemy.
  
  
• Add rigidbody & continuous collision detection to all objects
  
  
• Tweak PhysicsManager.DefaultContactOffset from 0.01 to 0.001, as suggested by Eliasar
  
  
• Switch from "PCM" to "Legacy Contacts Generation"
  

None of these worked so I'm feeling a little desperate. Thanks in advance for your help !

Code I use to stick the grenade upon collision :

void OnCollisionEnter(Collision c) {
rigidbody.isKinematic = true;
transform.parent = c.transform;
}

 

Use https://docs.unity3d.com/ScriptReference/Physics.OverlapSphereNonAlloc.html to detect collision manually.
Then do the same if it collides with something.
OnCollisionEnter tends to be somewhat unreliable when it comes to timing.

 

Thanks I will try. So I guess I should run OverlapShere inside FixedUpdate ?

 

Depends. If you move your grenade by the physics - then yes.
Otherwise check at the code where you're performing your movement.