Technician A says that a disc brake thickness variation of 0.0003″ (0.0076 mm) can cause brake pedal pulsations, requiring resurfacing or replacement of the brake rotors. Technician B says that disc brake systems need higher clamping force, which requires a brake booster. Who is correct?

Answer: Technician A and Technician B are both correct

Explanation:

Technician A is correct because disc brake thickness variation of 0.0003'' (0.0076 mm) can cause brake pedal pulsations due to excess absorption of heat and lead to to wear

Technician B says that disc brake systems need higher clamping force, which requires a brake booster so as the step on the break pedal will be with less effort since the disc brake system are not self energizing.

Both technicians A and B are correct

Explanation:

Disc brake thickness rotation is a brake rotor condition where opposite faces of the brake rotor accumulate an extra thickness of brake friction material or thinness due to increased wear. A brake rotor that has developed disc thickness variation causes brake pedal pulsation during braking.

Disc brake thickness should not vary more than 0.001" from one spot to another.

Lateral runout or uneven clamping forces are the two most common causes of Disc Brake thickness variation. Therefore, to avoid Disc Brake thickness variation, the clamping force must be very high, a brake booster can be used for this purpose.

Based on all the above theories, it is obvious that both technicians A and B are right.