I recently fitted a new steering rack to my wifes 1.8 TDCI Focus and it works a treat. Got the car 4 wheel aligned and it was as sharp as a new one. Wifes been driving it for the last 5 odd weeks and when I get in it to drive it the other day I noticed it felt really vague in a straight line or on changing direction.
Now when I changed the rack I checked the track rod ends and they were fine, wishbone ball joints were fine, replaced drop links, checked bushes etc., and all was fine. As I said the car handled like a new one. Tyre pressures are ok too.
The vagueness is only at speed, around 50mph plus, below that you dont really feel it, just a light feeling when driving straight. Over 50mph and changing direction feels like there is a slack bit at the point you actually change direction. Hitting bumps at this speed and you really have to keep correcting the wheel. There is no play at all in the rack when stationary. I checked it with a dial gauge on the road wheel and any movement of the steering wheel in either direction is instant.