I've still got some vibration and or shimmy on my Roadster at anything over 80mph. Has always been there and still is in spite of Suplex being fitted, new tyres all round (alloys not wires) which were carefully balanced by a good tyre shop who Mike Duncan uses and switching wheels around. The cars only done 2400 miles so can't be wheel bearings. It spoils the car.
It obviously bugged the previous owner as he had Richard Thorne rebalance at each annual service. Probably why he only did 700 miles in 4 years.
About the only thing I can think of is that the castor angle might not be equal on both sides of the car. It should be 6 degrees. A fraction more wouldn't be a problem, but anything less and you might get a bit of shimmy. I would take it to Peter Mulberry, he'd be able to sort it out.
