Brakes and abs

Hello. The brakes on my 300 tri auto with abs seem to be slipping then grabbing when come to a slow stop. Discs pads and wheel bearings were all replaced 6 months ago. Every now and again the brake pedal will go hard and a standing and grating noise comes from abs. Only happens at low speed. If you take your foot of brake pedal and press again it's ok. Thanks

Hi, it's sign of ABS kicking in which means the ECU considers there is a slip and activates the modulator to override it, important thing to have a well balanced system is to have all the sensors well seated in theyr's place as the air gaps to the exciter rings to be all equal, all 4 wheels to be same type, to have similar wear and pressure per axle and have standard dimensions((as recommended by the builder)) ... also make sure that no caliper is sticking and all the lines are properly bled... the system was calibrated from factory for all these elements so if any of them is out of original specifications the system can develop a missbehaviour, it can vary from one vehicle to another depending on weight, road conditions and driving style too ....if all of the above are ruled out and still no joy you should try with another ECU

Thanks. I will check sensors are seated properly and scalpers are all free. The tyres are all the same.I will also bleed the brake system.