How many kilometers do car brake discs usually need to be replaced?

The thickness of a typical brake disc is around 22mm,with a maximum allowable thickness of 19mm.The maximum allowable circular runout on the surface of the brake disc is 0.05mm.That is to say,if the brake thickness is greater than 19mm and the circular runout is less than 0.05mm,there is no need to replace or repair it.

Almost all brake discs are ignored in daily life.If they are replaced due to simple wear and tear,it is generally necessary to replace 2-3 pairs of brake pads before paying attention to the thickness of the brake disc.Regular maintenance and repair shops,even 4S stores,do not measure the thickness of brake discs.

When the steering wheel shakes during braking,it is basically due to abnormal brake discs.At this point,it is necessary to observe the circular runout on the surface of the brake disc.The so-called circular bounce simply measures the flatness of a plane.This requires the use of a dial gauge tool with a magnetic base for testing.It should be noted that the abnormal circular runout of the brake disc does not mean that it needs to be replaced.Of course,replacement is also possible.Generally,brake discs for household cars are made of cast iron.This brake disc is not expensive,usually around 2-300 yuan per one.If not replaced,the brake disc can also be ground.Grinding is the process of removing a layer from the surface of a brake disc to make it flat.Of course,the thickness of this brake disc also becomes thinner.

The brake disc is made of cast iron,so when the vehicle is parked for a short period of time,rust will appear on the surface of the brake disc.This is a normal phenomenon,there will be a clicking sound as soon as the vehicle moves.We just need to drive for a while.

After prolonged braking,it is not advisable to directly cool the brake disc with water,as this can cause deformation of the brake disc surface and abnormal circular runout.The direct manifestation is that the brake is shaking the steering wheel.