diff --git a/src/BulletCollision/CollisionDispatch/btManifoldResult.cpp b/src/BulletCollision/CollisionDispatch/btManifoldResult.cpp
index aa3d159f8..23c73c882 100644
--- a/src/BulletCollision/CollisionDispatch/btManifoldResult.cpp
+++ b/src/BulletCollision/CollisionDispatch/btManifoldResult.cpp
@@ -22,7 +22,12 @@ subject to the following restrictions:
 ///This is to allow MaterialCombiner/Custom Friction/Restitution values
 ContactAddedCallback		gContactAddedCallback=0;
 
-
+CalculateCombinedCallback		gCalculateCombinedRestitutionCallback = &btManifoldResult::calculateCombinedRestitution;
+CalculateCombinedCallback		gCalculateCombinedFrictionCallback = &btManifoldResult::calculateCombinedFriction;
+CalculateCombinedCallback		gCalculateCombinedRollingFrictionCallback = &btManifoldResult::calculateCombinedRollingFriction;
+CalculateCombinedCallback		gCalculateCombinedSpinningFrictionCallback = &btManifoldResult::calculateCombinedSpinningFriction;
+CalculateCombinedCallback		gCalculateCombinedContactDampingCallback = &btManifoldResult::calculateCombinedContactDamping;
+CalculateCombinedCallback		gCalculateCombinedContactStiffnessCallback = &btManifoldResult::calculateCombinedContactStiffness;
 
 btScalar	btManifoldResult::calculateCombinedRollingFriction(const btCollisionObject* body0,const btCollisionObject* body1)
 {
@@ -134,16 +139,16 @@ void btManifoldResult::addContactPoint(const btVector3& normalOnBInWorld,const b
 	
 	int insertIndex = m_manifoldPtr->getCacheEntry(newPt);
 
-	newPt.m_combinedFriction = calculateCombinedFriction(m_body0Wrap->getCollisionObject(),m_body1Wrap->getCollisionObject());
-	newPt.m_combinedRestitution = calculateCombinedRestitution(m_body0Wrap->getCollisionObject(),m_body1Wrap->getCollisionObject());
-	newPt.m_combinedRollingFriction = calculateCombinedRollingFriction(m_body0Wrap->getCollisionObject(),m_body1Wrap->getCollisionObject());
-    newPt.m_combinedSpinningFriction = calculateCombinedSpinningFriction(m_body0Wrap->getCollisionObject(),m_body1Wrap->getCollisionObject());
+	newPt.m_combinedFriction = gCalculateCombinedFrictionCallback(m_body0Wrap->getCollisionObject(),m_body1Wrap->getCollisionObject());
+	newPt.m_combinedRestitution = gCalculateCombinedRestitutionCallback(m_body0Wrap->getCollisionObject(),m_body1Wrap->getCollisionObject());
+	newPt.m_combinedRollingFriction = gCalculateCombinedRollingFrictionCallback(m_body0Wrap->getCollisionObject(),m_body1Wrap->getCollisionObject());
+	newPt.m_combinedSpinningFriction = gCalculateCombinedSpinningFrictionCallback(m_body0Wrap->getCollisionObject(),m_body1Wrap->getCollisionObject());
 	
 	if (    (m_body0Wrap->getCollisionObject()->getCollisionFlags()& btCollisionObject::CF_HAS_CONTACT_STIFFNESS_DAMPING) ||
             (m_body1Wrap->getCollisionObject()->getCollisionFlags()& btCollisionObject::CF_HAS_CONTACT_STIFFNESS_DAMPING))
     {
-        newPt.m_combinedContactDamping1 = calculateCombinedContactDamping(m_body0Wrap->getCollisionObject(),m_body1Wrap->getCollisionObject());
-        newPt.m_combinedContactStiffness1 = calculateCombinedContactStiffness(m_body0Wrap->getCollisionObject(),m_body1Wrap->getCollisionObject());
+		newPt.m_combinedContactDamping1 = gCalculateCombinedContactDampingCallback(m_body0Wrap->getCollisionObject(),m_body1Wrap->getCollisionObject());
+		newPt.m_combinedContactStiffness1 = gCalculateCombinedContactStiffnessCallback(m_body0Wrap->getCollisionObject(),m_body1Wrap->getCollisionObject());
         newPt.m_contactPointFlags |= BT_CONTACT_FLAG_CONTACT_STIFFNESS_DAMPING;
     }
 
diff --git a/src/BulletCollision/CollisionDispatch/btManifoldResult.h b/src/BulletCollision/CollisionDispatch/btManifoldResult.h
index 86bbc3f72..12cdafd1b 100644
--- a/src/BulletCollision/CollisionDispatch/btManifoldResult.h
+++ b/src/BulletCollision/CollisionDispatch/btManifoldResult.h
@@ -34,6 +34,15 @@ extern ContactAddedCallback		gContactAddedCallback;
 
 //#define DEBUG_PART_INDEX 1
 
+/// These callbacks are used to customize the algorith that combine restitution, friction, damping, Stiffness
+typedef btScalar (*CalculateCombinedCallback)(const btCollisionObject* body0,const btCollisionObject* body1);
+
+extern CalculateCombinedCallback		gCalculateCombinedRestitutionCallback;
+extern CalculateCombinedCallback		gCalculateCombinedFrictionCallback;
+extern CalculateCombinedCallback		gCalculateCombinedRollingFrictionCallback;
+extern CalculateCombinedCallback		gCalculateCombinedSpinningFrictionCallback;
+extern CalculateCombinedCallback		gCalculateCombinedContactDampingCallback;
+extern CalculateCombinedCallback		gCalculateCombinedContactStiffnessCallback;
 
 ///btManifoldResult is a helper class to manage  contact results.
 class btManifoldResult : public btDiscreteCollisionDetectorInterface::Result
diff --git a/src/BulletDynamics/Dynamics/btDiscreteDynamicsWorld.cpp b/src/BulletDynamics/Dynamics/btDiscreteDynamicsWorld.cpp
index fc85b4f86..a196d4522 100644
--- a/src/BulletDynamics/Dynamics/btDiscreteDynamicsWorld.cpp
+++ b/src/BulletDynamics/Dynamics/btDiscreteDynamicsWorld.cpp
@@ -952,7 +952,7 @@ void btDiscreteDynamicsWorld::createPredictiveContactsInternal( btRigidBody** bo
 						int index = manifold->addManifoldPoint(newPoint, isPredictive);
 						btManifoldPoint& pt = manifold->getContactPoint(index);
 						pt.m_combinedRestitution = 0;
-						pt.m_combinedFriction = btManifoldResult::calculateCombinedFriction(body,sweepResults.m_hitCollisionObject);
+						pt.m_combinedFriction = gCalculateCombinedFrictionCallback(body,sweepResults.m_hitCollisionObject);
 						pt.m_positionWorldOnA = body->getWorldTransform().getOrigin();
 						pt.m_positionWorldOnB = worldPointB;
 
@@ -1113,7 +1113,7 @@ void btDiscreteDynamicsWorld::integrateTransforms(btScalar timeStep)
 			for (int p=0;p<manifold->getNumContacts();p++)
 			{
 				const btManifoldPoint& pt = manifold->getContactPoint(p);
-				btScalar combinedRestitution = btManifoldResult::calculateCombinedRestitution(body0, body1);
+				btScalar combinedRestitution = gCalculateCombinedRestitutionCallback(body0, body1);
 
 				if (combinedRestitution>0 && pt.m_appliedImpulse != 0.f)
 				//if (pt.getDistance()>0 && combinedRestitution>0 && pt.m_appliedImpulse != 0.f)