Steering problem

Hi, I have a 2011 SD4 HSE the vehicle drive perfectly on the straight not a wobble or any towing to one side and it corners fine at low speed. However at higher speeds 40 and above the steering will rock/pump on bends and roundabouts. The PAS fluids are fine, the balancing and tracking perfect. It doesn’t seem to affect the line the vehicle is taking but it doesn’t fill you with confiedence on a bend and you feel like you need to keep adjusting the wheel. Anybody got any ideas?

Are you running 4 identical tyres? ie make & model and all pumped to same pressure? Discrepencies can cause the 4WD system to get confused.

Do you have any bulges in the tyres? Are the wheels bent or buckled? Any sign of curbing damage?
Really you need to lift each wheel in turn and spin them to check for buckles.

All wheels secure with no warped discs or lost balance weights?