Abs ligt on clunking noise

replace the caliper and rotor and brake pads

Sounds like left front loose wheel bearing knocking ABS sensor out of range causing ABS light to come on and causing grind noise at same location. Grinding noise is probably rotor rubbing on calipar.

Check rotor not touching caliper or wheel,

If fluid leaking from the master cylinder finds a way into the servo or booster it could cause an entirely different sort of trouble. Master cylinders are usually very reliable unless contamination of the fluid has taken place - usually indicated by a darker than usual fluid colour and sediment in the reservoir, evidenced when a strong light is used.

A loss of brake pressure could signal the master cylinder is failing (the pedal creeping towards the floor) or a brake booster problem, perhaps caused by insufficient vacuum or an air leak. An assistant is useful when looking for such problems and also when searching for noises.

The steady clunk being felt on the brake pedal might be something fairly obvious like a wheel balance weight just touching a caliper when the brake is applied. It is time to become a detective - I recently had one of those. One wheel had a second row of balance weights that caused no problems until I fitted new brake pads.

If a close and careful examination and a vigorous shake of everything by an assistant provides no clues, it could be worth checking the air gap between the ABS sensor(s) and the reluctors if they are the exposed type. Sometimes corrosion reduces the diameter of the reluctor and increases the air gap so the signal is lost at low speed. The ABS brain thinks the wheel is not turning and tries to operate the ABS on that wheel. Usually not a steady clunk but you never know, it could be worth checking...

CHECK SENSOR ON THE PADS, OR BRAKE SIDE

probably a dumb question, but if there is a backing plate, did you make sure it isnt bent and hitting the rotor? you never want to sand new rotors, although i dont think it would cause this concern. i would suggest lightly scuffing up the brake pads. this will eliminate any noise caused by the contact of the rotors and pads. if it goes away then you know its a problem with the pads/rotors.

scoring of only the inside rotors would make me think that possibly the caliper slides are frozen up. make sure they move quite freely on the slides. it is not uncommon for brake pads to score rotors though.

but brake noises at low speeds that dont' change when applying light brake pressure are usually some sort of metal or something contacting the rotor.

Brake pads are worn out. The ABS light would not come on because there is nothing wrong with the ABS. The grinding you are hearing are the brake pad backing plates rubbing against the rotor. You should have heard a high pitched squeal long before this happened. More than likely the rotors are now destroyed and will need replacing or at the very least turned in a machine shop. Fix this yesterday.

These definitely sound related. Need to inspect to see if it's something loose (like a wheel sensor) or the brake pads need replacing, etc. etc...

Charlie

Front hub bearing. If you were the one who replaced the pads you should have turned the hub while the caliper was off and checked for roughness or wobble. Imagine the rotor wandering from side to side and rubbing the pads; thats what a worn hub will do.

sounds like u need front brake pads and rotors i would check brakes first if ok then i would check front wheel bearings but cv joints make a clicking sound usauly when turning