diff --git a/src/BulletDynamics/Featherstone/btMultiBodyDynamicsWorld.cpp b/src/BulletDynamics/Featherstone/btMultiBodyDynamicsWorld.cpp
index 1be76ad86..f5a7a7f1e 100644
--- a/src/BulletDynamics/Featherstone/btMultiBodyDynamicsWorld.cpp
+++ b/src/BulletDynamics/Featherstone/btMultiBodyDynamicsWorld.cpp
@@ -588,15 +588,14 @@ void btMultiBodyDynamicsWorld::solveExternalForces(btContactSolverInfo& solverIn
                 {
                     if (!bod->isUsingRK4Integration())
                     {
+                        // avoid damping in external forces (e.g. gravity)
                         const btScalar linearDamp = bod->getLinearDamping();
-//                        const btScalar angularDamp = bod->getAngularDamping();
                         bod->setLinearDamping(0);
                         bod->computeAccelerationsArticulatedBodyAlgorithmMultiDof(solverInfo.m_timeStep,
                                                                                   m_scratch_r, m_scratch_v, m_scratch_m,isConstraintPass,
                                                                                   getSolverInfo().m_jointFeedbackInWorldSpace,
                                                                                   getSolverInfo().m_jointFeedbackInJointFrame);
                         bod->setLinearDamping(linearDamp);
-//                        bod->setAngularDamping(angularDamp);
                     }
                     else
                     {
diff --git a/src/BulletDynamics/Featherstone/btMultiBodyLink.h b/src/BulletDynamics/Featherstone/btMultiBodyLink.h
index 1cd6b8c07..565bb6b3e 100644
--- a/src/BulletDynamics/Featherstone/btMultiBodyLink.h
+++ b/src/BulletDynamics/Featherstone/btMultiBodyLink.h
@@ -157,6 +157,7 @@ struct btMultibodyLink
 		  m_parent(-1),
 		  m_zeroRotParentToThis(0, 0, 0, 1),
 		  m_cachedRotParentToThis(0, 0, 0, 1),
+          m_cachedRotParentToThis_interpolate(0, 0, 0, 1),
 		  m_collider(0),
 		  m_flags(0),
 		  m_dofCount(0),
@@ -179,6 +180,7 @@ struct btMultibodyLink
 		m_dVector.setValue(0, 0, 0);
 		m_eVector.setValue(0, 0, 0);
 		m_cachedRVector.setValue(0, 0, 0);
+        m_cachedRVector_interpolate.setValue(0, 0, 0);
 		m_appliedForce.setValue(0, 0, 0);
 		m_appliedTorque.setValue(0, 0, 0);
 		m_appliedConstraintForce.setValue(0, 0, 0);