Volvo: 1993 volvo 940 sporatic steering vibratrion, 1993 volvo 940, volvo 940

Question
My car has a vibration, but it doesn't start until after I have driven it a while and occurs over 40 miles an hour. At times it is smooth and no problem, then other times it vibrates (left to right not up and down). Not an expert, but have had arm-shaft replaced rt front, brake line replaced, strut rt front, alignment done and then re-done, tires rotated, and rt front rotar turned. Each time the car seems fine for a while then it re-emerges. It is driving me crazy!

Answer
Tom,
You need the help of a front end specialist. Tires will need to be inspected and balanced, the rotors checked for run out and a inspection of all front end componants. Do not forget to have the power steering pump tested and also the rack. Can you take a tech out for a ride and show him the vibration?