please help!!!

i got home the other day in my 2002 wrx and as i was reversing it onto the drive, i felt something wrong. it felt at first as though i had a flat front tyre, but when i got out to check, it was fine! i got back in again and whilst on (almost) full lock it did it again!! im wondering if my steering rack is on the way out?! it makes a type of knocking noise. i took it to a garage to have it look at, but there is nothing visably wrong with it!!

 

were you reversing whilst cold i have the same problem check that your belts on your front pulleys are not worn mine is and needs replacing

 

no, it only really does it when its warm and after a long drive. can also smell burning oil.