Meritor MM-0861 - User Manual

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Overview

The provided document is a maintenance manual for Meritor MTC-4208X/XL/XP/XLEV/XLEC, MTC-4210X/XL/XP/XLEV/XLEC, and MTC-4213X Series transfer cases. These transfer cases are four-shaft designs with two-speed front and rear output, offering a 1:1 and a 1:2.05 ratio. They are designed for use in part-time 4x4 and 6x6 vehicles. Specifically, the MTC-4208 and MTC-4210 Series are intended for 4x4 vehicles, while the MTC-4213 Series is for 6x6 vehicles, forming part of Meritor's medium-duty 4x4 drive system.

The transfer cases feature an air-actuated front-axle declutch (if equipped), a high and low shifter, and a full-torque power take-off (PTO) lockup, all controlled from the cab. The declutch allows shifting from part-time 4x4 or 6x6 operation to rear-wheel drive (RWD). Engagement can be confirmed by sound, improved vehicle performance, or an optional indicator light in the cab. The declutch should only be engaged in off-road or poor traction conditions, or when the vehicle is stationary or operating at constant low speed (below 10 mph or 4 km/h). Speeds under 20 mph (32 km/h) are recommended for part-time 4x4 or 6x6 operation. Engaging the declutch on slipping wheels or steep grades can cause instability, personal injury, and component damage.

The two-speed output provides high and low ranges, along with a neutral position for PTO-equipped transfer cases. Non-PTO cases may have this neutral position plugged with a breather. The full-torque PTO option provides an outlet for driving auxiliary power devices, with optional switches indicating full engagement or disengagement. The PTO can be operated in high, low, or neutral range. When operating the PTO in neutral range, engine RPM should not exceed 2,000 rpm, and the transmission shift range and engine RPM must be controlled to prevent exceeding this limit. The PTO should only be engaged or disengaged when the vehicle is stationary, the transmission is in Neutral, and the transfer case prop shafts are not turning. Loading the driven auxiliary device should be avoided until the PTO is fully engaged.

An optional speed sensor measures transfer case output driveline RPM. Optional switches indicate when the front axle declutch is fully engaged or disengaged.

Vehicle configuration significantly impacts these transfer cases. Vehicles with overdrive transmissions used primarily for high-speed highway routes experience higher transfer case input speeds. Operating temperature is mainly influenced by input speed, regardless of RWD or part-time 4x4/6x6 operation. An optional oil cooler reduces operating temperatures, improving yoke seal life, reducing oil degradation, and decreasing the likelihood of oil and air leaks. Meritor recommends routing oil cooler lines with a P-trap configuration to prevent oil flow back into the transfer case sump, which could otherwise give the appearance of an overfilled transfer case.

The breather system, located on the rear cover for the high/low shifter, prevents housing pressurization if an O-ring is damaged. All range shifts require full-time pressurization, so a damaged O-ring could allow air to fill the housing, potentially damaging yoke seals or causing oil leaks.

The manual specifies various torque values for fasteners, including bearing cage cover capscrews (85-115 lb-ft), yoke lock nuts (700-900 lb-ft), and shift cylinders (80-100 lb-ft). Lubrication requires SAE Grade full-synthetic 40W or 50W oil (Meritor specification O-81). API GL-5 oils, petroleum-based, and multi-viscosity motor oils are not approved due to potential sludge formation and component damage. Initial oil fill volumes range from 12.50 to 13.50 pints (5.92 to 6.39 liters) depending on the model. Oil cooler-equipped transfer cases require additional oil to compensate for the cooler and lines.

Maintenance involves regular inspection for leaks (daily), oil level checks (every 1,000 miles/100 hours/month), and oil changes (initial at 2,500 miles/125 hours, synthetic every 25,000 miles/1,250 hours/12 months). Magnetic drain plugs should be cleaned and reinstalled, or replaced if their pick-up capacity of 20 ounces (0.57 kg) of low carbon steel is compromised.

The manual provides detailed instructions for disassembly and assembly, including specific tools and procedures for removing and installing components like input shafts, idler gears, and bearing cups. End play checks for various shafts are critical, with specifications typically ranging from 0.002-0.006” (0.051-0.152 mm) for most shafts, and 0.002-0.004” (0.051-0.102 mm) for the MTC-4213X input and upper rear output shafts. Shims are used to adjust end play.

Safety precautions emphasize wearing eye protection, appropriate personal protective equipment, and avoiding loose clothing or jewelry. Work should be performed on a flat, level, well-lighted, and ventilated surface, with the vehicle supported by safety stands. The engine must be off and the ignition key removed before working on the vehicle. Hot parts and fluids can cause burns. Compressed air should be used cautiously, and air systems drained before disconnecting lines. Only Meritor® brand replacement parts should be used to maintain warranty and prevent damage or injury. Steam cleaning requires closing or covering all openings to prevent component damage. Adhesives and silicone gasket materials, such as Loctite® 5699 Ultra Grey or Permatex® 82194 Ultra Grey, must be applied in continuous 0.125” (3 mm) beads to prevent clogging lubrication passages. Fasteners secured with adhesive may require heating for removal.

Towing instructions recommend removing both axle shafts from axles that remain on the road or removing drive shafts from axles that contact the ground to prevent internal damage to the transfer case.