Vehicle is X5 E53 3.0d 2005 facelift. When turning right and under hard acceleration to join traffic I experience a hard thump from the transmission. I don't get this when travelling straight. Any ideas of the issue would be welcomed. Recent work included new front tyres of the correct rolling radius, fluid changes to autobox and transfer box. This did not make a difference to the issue which appears to be more prominent when the car is cold.