It sounds like the right is wanting to brake more than the left. Or maybe the reverse is the situation, The left won't brake as much as the right when you brake hard.
I'm assuming because you said everything is new that would mean Cyl., return springs, shoes, right ?
The only other thing I can come up with is the possibility of something in the suspension moving when you brake hard causing the pull to the right.
I would think that it could also include steering components.
You might try having someone watch your front end as you brake to see if they can notice anything strange.
Dan
