From what I've heard before, its because the power steering aid is trying to turn the wheel further then it can go, and hence its being strained.
Apparently it's not good/you're not meant to full lock on PS cars, and there is like a point where its full lock but not FULL full lock if you know what I mean.
Apparently it's not good/you're not meant to full lock on PS cars, and there is like a point where its full lock but not FULL full lock if you know what I mean.