aoa.i own a charade 1985 and encountering a new problem from like 6 months or so,if i go a little hard on the brake pedal it feels that the front tires get locked and the rear tires are still moving and the car will skid sideways depending on the steering direction,even at low speeds the car will not skid side ways but will keep on moving with the tires jammed(can feel the front one dont know abt rear).i checked my front disks and pads,replaced the pads got the front plate tooled,checked rear brake leather,changed the rear brake leather made as close to the drum as possible,checked the rear brake drums too,got them cleaned as well,tires on the front are new like 2 3 months old and rear are a yr old all were brought brand new,however the brake fluid is kinda blackish,my mechanic told me that ur master cylinder is weak and if u drained this brake fluid out and filled with newer clean fluid ur master brake cylinder might become more weak and if u changed ur master cylinder ur lines may burst,the new lines and master cylinder are costing arround 4.5k,iam okay with replacing it but before doing it i want to ask that whether its the cause or not?or sth else seems to have gone wrong. @xulfiqar bhai need ur expert advise sir thanku v much