If the vehicle pulls to the left only while braking, suspect a problem with the front right side brake unit. It's pulling because the left side brake unit has more clamping force than the right or opposite side brake unit does. This is can be caused by a kink in the line, a hose, or a seized caliper. A complete visual brake system inspection will be in order. Sometimes the hose is accidentally twisted when replacing the brake caliper. It's wise to double check brake work upon completion.