Paper explains conversion of existing drum brake system to disc brake system with complete digital validation at structural as well as thermal level to make sure First Time Right Design before physical part development. To provide leverage to quick design, modification and selection of brake system according to vehicle configuration, a virtual computational fluid dynamics (CFD) simulation process is developed and validated with test results. Temperature variation over brake drum and disc in internal standard braking cycle is measured virtually and correlated with test results. Also Fade testing criteria’s were considered during CFD analysis.This up gradation is must considering technology enhancement trend and safety in automotive segment. In current competitive market scenario and as per customer requirements, front disc brake module is becoming necessary not only for passenger segment but also for commercial segment vehicle. Brake system design is challenging task as it deals with safety norms and also required to meet stringent performance. Brake Rotor is very important component in brake system which is expected to withstand high braking torque and dissipate heat during braking event. Hence proper design and selection of braking system is very important before implementing on vehicle. Also rigorous testing process to measure the temperature rise of disc, calliper and hub of brake system is very important along with physical testing at vehicle level.Brake rotor is major part of disc brake system and First step of development is design calculation, followed up with CAD model preparation and later on CAE. All vehicle level structural loads considered during digital/CAE validation and post structural analysis, CFD analysis is completed. Detailed brake thermal loading cycle in terms of braking heat flux, meshing methodology and simulation processes revealed in paper. A transient simulation of three different types of disc profile performed. In transient thermal simulation of brake system, maximum temperature rise over disc and pads at different location are monitored and evaluated. These were compared with similar case of drum brake system. Based on conduction heat loss and convection heat loss calculation, the brake cooling effect is evaluated. Finally after confirmation from CFD analysis Brake rotor/ Brake system design frozen.All digital simulation results co-related with physical rig level and vehicle level testing, and results were acceptable. Finally weight optimized disc brake system meeting all performance criteria implemented in 8 × 2 commercial vehicle at all wheel ends. It resulted in customer delight with 20% payload increment and performance improvement from drum brake system to Disc brake system.