Intermittent grinding noises

[Smarty2]

Hi all, my C5 petrol auto is making some grinding noises from I think but can't be 100% sure the offside front, it only happens when at operating temp and doing a left hand turn and straightening up again? There's no jerkiness from the dreaded Al4 and changes smoothly when hot. Garage have no idea until the noise becomes permanent or obviously something fails! Hoping it isn't the diff in the Al4? They checked the drive shafts and reported all was tight. Another mystery but thought I'd check here to see if anyone else has experienced this?
Regards