I did not use the ABS from my 2002 donor but I did use the stock calipers, if you check my build thread you will see in one of the go-kart videos that the fronts do lock first with the proportioning valve wide open. I have since started to adjust it to even things out. Still fine tuning on every test. Keep in mind as well the adjustment is counter-intuitive (screw in vs. screw out).