Yes sorry, i knew about the weight sensing brakes, i ment that they both take on a similar work load, most cars leave the majority of braking to the fronts, or so it seems. Although the suspension set up possibly accounts for that too.
No, the noise comes from the front, if i move the height lever it stops the noise. When it groans the car isnt moving, it doesnt make any noises going from high to low. I thought it was something to do with the antisink valve, but im not sure why it should do it sometimes and not others.
Actually, thinking about it, its normally when i park the car on full lock, where the front of the car jacks up due to the tyres scrubbing and it then settles when its parked. Its more of an electrical type groan, as the car is still when it happens.
Its not the only one ive heard make the groaning noises, so i assumed it was normal?