The aim of this research is to study the varieties of weight density distribution affect to the center of mass and vehicle stability. The weight density distribution tester was designed and changed the position of mass. Base on the center of mass is main points of vehicle stability. On the other hand FMCSA standard was applied to field test for considering of the brake performance and vehicle stability. The results of research discovered to the mass distribution on longitudinal plane are affected to the center of mass and absolutely influence at the right wheel on the front axle. In term of the braking performance it’s depends on the lateral mass distribution especially the center position of mass installed on longitudinal and horizontal plane and close up on the front axle (Y2). For the vehicle stability results the position (Y2) is the highest influence for yaw rate and sideslip. Otherwise the position (Y3) or the position of mass installed on longitudinal plane and nearly at the left wheel on the rear axle. Additionally wheel lock-up condition was appeared on the front axle only. Because the behavior of weight distribution on the front axle was decreased lead to mass distribution on longitudinal plane.

The aim of this research is to study the brake proportional affected to vehicle stability. Braking performance and vehicle stability testing are the main of research purposes. Otherwise learning research center and new researcher in automotive engineering are the minor research objectives. The results of research discovered to the braking performance depend on driver behavior. By the minimum deceleration was appeared on the non-proportion in front axle with braking ratio 0:100. In term of vehicle stabilities yaw and pitch moment are normally occur by the driving behavior. But the sideslip is an absolutely effect to vehicle handling. With the braking ratio 100:0 there is the highest risk for controlling a vehicle cause of the wheels were locked-up condition in the rear axle. Therefore the value of the sideslip was exceeded with the criteria. Furthermore these project researches were got the learning research center and the new researcher in automotive engineering field.

Brake system is used the friction between disk and pads. In the driving conditions the brake behavior from the driver is difference. Based on this reason the damage on disk and pads are occurring. Nowadays the ratio of compound materials in pads is several and involved automotive industry has not available enough to experiment. Thus it is difficult to brake pads damaged analyzing in several driving conditions. In this problem the mechanical property tester is main tool for experimenting. And test procedure based on the Brake lining and disc brake pads compressibility JIS D 4413 [7]. The experiment emphasizes on the flexibility behavior and internal energy by volume with 3 types of brake lining and pads. For the experiment focused on conditions by normal apply brake repeat apply brake and suddenly apply brake. The results revealed the normal apply brake condition the maximum and minimum of flexibility behavior was appeared on brake lining and pads type A and type C with testing temperature at 2000C. By the repeat and suddenly apply brake conditions the brake lining and pads type C and type A with 300C is given to the maximum and minimum flexibility behavior. In case of internal energy by volume the maximum and minimum energy was appeared on pads type C and B at the 300C of testing temperature. For the testing temperature at 200 and 4000C the pads type A and type B were got the maximum and minimum energy respectively. On the other hand at the high flexibility behavior is given to high internal energy at the high temperature of the apply brake condition.

Admittedly a disc brake plays an important role in the auto part industry since it concerns directly with safety. Therefore the wide range of disc brake has been designed in order to develop its heat ventilation. There are two physical kinds of brakes: front-vented disc brake and backvented disc brake. As a result such difference affects directly to the heat ventilation which is a vital factor of the brake’s capability. The project team recognizes its importance and tries to create the test to find out the temperature diffusion of the disc brake with the hope to evaluate the coefficient of the heat convection varied by the temperature changing in both kinds of brakes under the forced heat convection in the steady condition. However the steady heat conduction and radiation value will not be counted because it is insignificant. The JASO C406: 2000 Standard is adopted as a guideline in the test. The outcome coefficient of heat conduction will be used in the simulation via the Finite Element Method (FEM) in order to study the temperature diffusion and heat ventilation of both kinds of brakes at each temperature level. Consequently the experimental work reveals then the heat convection coefficients of both kinds are unidirectional. The heat convection coefficient of the front-vented disc brake is 4.40 % in average higher than that of the back-vented disc brake. From the simulation the front-vented disc brake can ventilate the heat better than the back-vented disc brake at 3.02 % in average. It can be summarized that the front-vented disc brake has more temperature difference than the backvented disc brake. Hence the front-vented disc brake likely gets more stress from the temperature than the back-vented disc brake and might be damaged during the operation more than the another type.

Nowadays the automotive industry in Thailand has been widely growing. Brake pad is one of the automotive products that play a vital role in automotive industry because it is the most critical seeurity part. Consequently testing products for quality are extremely requested. However the precise equipment and function tests which show the real effects are not available enough and cost a lot. Therefore they cannot response to the deman in the automotive industry development. In this study the frictional test jigs for friction measurement JIS K7125 [5] and the clutch facings for automobiles JIS D4311 [6]. A study of the frictional test emphasizes on the static friction (μs) and kinetic friction (μk) in different condition. There are 3 specimens of brake pad supposted by the industry company. These specimens were tested and the results from the pin-ondisk and those from the friction testing were compared. The results revealed the correspondence of the two-sided results but the pin-on-disk’s friction coefficient is more than the friction testing’s friction coefficient by 19.56%. Moreover the coefficient of friction varies according to the temperature Besides the static friction (μs) is likely more than kinetic friction (μk) and tends to differ considerably under high pressure condition.