Tankslappers

Hi
I'm starting to get the beginnings of a tank slapper whenever I accelerate hard or go over 100mph which has been ok so far as its only happened on long straight roads not twisty ones. I recently changed tyres to michelin road pilot 2's and have turned the compression down on the rear shock. Would these things perhaps cause this to happen or is it something else never had this problem when I had the corsa 3 tyres on. Also I'm going to get the wheels balanced to be sure aswell

You could experiment with adding .5 - 1 turn of high speed comp, add some preload, or add compression. I'm speculating, but my guess is at speed you're compressing the rear suspension enough to take weight off the front wheel and causing the instability.

High speed comp dampening on the off-road bikes acts similar to a ride height adjuster, it doesn't seem to make the suspension harsher in the initial stroke, but does hold it up in the stroke reducing the tendency to squat. Doesn't sound right when you hear it but it does have an effect.

If you haven't checked your rear sag, keep in mind springs sag with age so your static sag will gradually increase over time.