yeah, margarine is made up of a lot of water and will not make a decent crust at all. my stand by recipe for pies and quiche:
2 cups all purpose flour
1 tsp salt
pinch sugar
1 cup unsalted butter, diced and frozen
1/3 cup (more or less) ice water
blitz dry ingredients in food processor. add frozen butter and blitz again till the biggest pieces of butter are the size of peas. i now dump this mix into a bowl and finish by hand. slowly add ice water and mix until the dough doesnt crumble into sand once you press it together.
at this point, it will still be somewhat falling apart, but you need to press it together and put it in the fridge wrapped for at least 30 mins before rolling.
margarine doesn't have a place in the pastry kitchen, there are no benefits to using it. if you're making a quiche, make a proper quiche, and the result will be much more satisfying
