Why would your vehicle pull to one side when braking even though it stops ok?

It might have a caliper sticking, or worn brake pads. This can also be caused by bad ball joints. If that doesn't help, you may need an alignment. Check to see if it pulls when driving also. It won't pull as hard as when you stop, but if it does the alignment is off. Low tire pressure on the suspect side can cause the car to pull under braking. Possible contamination.