The Suspension System
The suspension connects the frame to the wheels of the vehicle. It also allows contributes to the handling of the vehicle and the comfort of the passengers. The springs and struts/shocks absorb bumps in the road. Control arms, control arm bushings and ball joints allow the wheel to move up and down. The wheel bearing, hub and knuckle assembly connect the wheel to the control arm.
Sealed wheel bearings usually have an inner and outer race where the balls or the rollers can ride out. A rubber seal is inserted between the two races to keep the grease inside the bearing. The sealed wheel bearing is usually located near the spindle of the vehicle and allows the wheel to turn with a low amount of friction. Hub wheel bearings come as a hub assembly and wheel bearing combination.
The Exhaust System
Exhaust is collected from the cylinder head by the exhaust manifold. It diverts gases into one single pipe. Exhaust normally travels through a catalytic converter where harmful gases are converted to inert gases. Exhaust gases then pass through a muffler, which decreases the noise of the exhaust. Finally, gases exit the exhaust through the tailpipe. The tailpipe is normally located at the rear of the vehicle where exhaust gases have little or no chance of entering the passenger compartment.
The Catalytic Converter (often referred to as the Cat) contains a honeycomb structure that is coated with a catalyst such as platinum or palladium. When the cat becomes damaged inside, the flow of exhaust gasses can become restricted, causing the engine to suffer a severe loss of power.