I've just struggled with these (the standard rubber with bulge in the middle and screw type.
I don't know if the problem was because the toilet is 40mm thick at the holes but when I tightened them up they just popped out of the top. Is this normal or is the porcelain usually thinner (it's a GSI Italian toilet) to allow the bulge to expand below the hole?
I sorted it by using longer screws and some plastic tube spacers to keep the bulge at the bottom of the hole.
I don't know if the problem was because the toilet is 40mm thick at the holes but when I tightened them up they just popped out of the top. Is this normal or is the porcelain usually thinner (it's a GSI Italian toilet) to allow the bulge to expand below the hole?
I sorted it by using longer screws and some plastic tube spacers to keep the bulge at the bottom of the hole.
