Engine and Drivetrain

Good performance and low lifecycle costs come from correctly matching components to application, followed by proper operation and maintenance

• For longer drivelines, adhere to proper applications and load ratings. Using the proper lubricant and maintenance intervals will also help maximize driveline life.

• Checking and adjusting driveline angles will also maximize the life of the driveline, as well as other drivetrain components. Do not overload. Specify components that match the engines maximum torque, including higher torque when the engine is re-rated for resale.

• If purchasing a stock truck, make sure that the components are rated for the gvw and gcw ratings of the intended application. If the vehicle needs to be modified, get the OEM's approval for the proposed changes.

• Utilize an air dryer to reduce contamination of the air system. With newer engine oils, a coalescing desiccant cartridge is recommended.

• If spec'ing wide-base tires, be sure to check hub specification to avoid severe strain on the axle housing. Use of two-inch offset wheels can reduce outer wheel bearing life. Premium wheel bearings should be used with wide-base wheels along with pre-set hub packages. Consult the manufacturer's guidelines as needed.

• In some applications and operations, synthetic axle and transmission lubricants can provide advantages over petroleum-based lubricants. In particular, there are also some physical differences that make synthetic oils appealing. Because synthetic lubricants are typically lower viscosity fluids, they result in lower dynamic operating temperatures and that, in turn, results in longer lubricant life.

Synthetic axle and transmission lubricants also typically contain anti-wear additives and rust, oxidation and corrosion inhibitors which work to reduce component wear and promote longer component and lubricant life.

• When spec'ing components, pay attention to the weight. Lightweight components, such as aluminum carriers and Meritor SteelLite X30 brake drums can take significant pounds out of a drivetrain. Since the components are lightweight, it takes less energy to move the truck, resulting in improved fuel economy.

While many lightweight components are premium items at the front-end of the sale, the initial cost will be paid back through the life of the component through lower maintenance costs and less downtime, note ArvinMeritor officials.

• Be mindful of contaminated lube conditions, often predicated by moisture in the spring of the year. Consider conducting regular oil analysis to manage the vehicle performance. A good rule of thumb: check for leaks, lube levels and oil appearance.

• Brake over adjusting causes improper functioning of an automatic slack adjuster (ASA). If something is causing the unit to over-adjust that is external from the ASA, do not replace the stroke-sensing ASA unless it's mis-applicated. Check for the cause of problem - correct application (length and piston color), air system compounding, chamber bracket flexing, camshaft twisting, brake lining compression, etc.

• On a hydraulically-actuated clutch, it is important to note that the tips of the release yoke are in constant contact with the release bearing at all times. This contact may result in polishing, which is not detrimental to clutch operation. However, ArvinMeritor does recommend lubricating this contact area during routine PM maintenance. Refer to the OEM maintenance procedures, the officials advise.

• Keep in mind that "clutch adjustment" restores the designed clamp load to the clutch assembly and also restores the original angularity at the yoke tip/release bearing mating surfaces. Improper angularity can cause binding, increased pedal effort and possible early component wear.


While the driver through his driving habits remains the most important factor is fuel economy - good or bad, drivetrain specifications impacts fuel efficiency in heavy duty vehicles. All drivetrain specifications directly effect how efficiently the energy output of the engine is transferred to the tires. The correct specs can help ensure that the engine operates at its optimal speed for any given operation.

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