See also http://www.bulletphysics.com/Bullet/phpBB3/viewtopic.php?f=9&t=2677 and http://code.google.com/p/bullet/issues/detail?id=227 To enable, use constraint->enableFeedback(true); And then either use constraint->getAppliedImpulse() for an estimated applied impulse, or constraint-> getAppliedLinearImpulse(), or constraint->getAppliedAngularImpulseA() or constraint->getAppliedAngularImpulseB(). +removed a few warnings.