Ok, daft questions first. Fitted springs - were they the correct rating for the car? most road springs have color codes to rate the spring for the weight of a vehicle, eg 2.0 springs would mahe a 1.1 higher at the front because of the difference in engine weight. Are the springs "Lowering springs" if so, will affect ride height. Finally, re vibration, do the strut mounts have a top bearing, and if so is it ok? Just had to replace the top bearing on my mondeo after changing a spring, as the bearing collapsed a week later, causing horrendous low speed rattle, and stiff steering when moving off from a standstill
Mark The Bus, June 2011