When the road is wet and I accelerate too much I get an awful knocking sound as if the wheels briefly lift from the ground and suddenly grab again (that cycle repeating rapidly). In the dry the wheel spins like it normally should and I hear no knocking, at least with tyres in good condition.
So this problem is somehow related with very poor traction conditions and excessive wheelspin, but I dont know if the problem could be with engine mounts or the suspension... thing is, I have the Koni Sports with -50mm springs (which dont make the car 50mm lower, maybe the shocks are too long), which cause the springs to be a bit "loose" inside the shocks.
The car is an 1.2 16v with the 1.6 16v engine (and 1.6 engine mounts). The gearbox lower mount is much stiffer than stock (from the competition Clios) - fitted so that the gear lever doesnt move with the cars acceleration/deceleration.
PS - my friend has a phase1 1.6 16v with -40mm springs, stock shocks and stock engine/gearbox mounts, and he gets the same knocking sound in the same conditions - however in much, much smaller scale.