The Meritor MX-120 and MX-120-EVO Series are medium-duty front drive steer axles designed for use with Meritor MTC-4210 and -4213 transfer cases, forming part of a Meritor medium-duty part-time 4x4 or 6x6 system. These axles are typically applied in utility vehicles, snow plows, block trucks, and oil drillers.
Function Description:
These axles provide front-wheel drive and steering capabilities for medium-duty vehicles. The design incorporates features for durability, ease of maintenance, and compatibility with modern vehicle systems like Anti-Lock Braking Systems (ABS). The MX-120-HR (High Retardation) Series offers enhanced braking capabilities.
Important Technical Specifications:
- Axle Capacities: Single axle capacities range from 10,000 lb (4,536 kg) to 18,000 lb (28,968 kg) GAWR (Gross Axle Weight Rating).
- Brakes: Equipped with 16.5 Q+™ cam brakes featuring outboard-mounted brake drums.
- Wheel Mountings: Hub-piloted wheel mountings for 10 stud x 11.25-inch wheels.
- King Pins: Feature Easy Steer™ king pin bushings.
- ABS Compatibility: ABS-ready wheel-ends with pre-installed tooth wheels and sensors.
- Carrier Types:
- Standard MX-120 Series carrier with hypoid gearing and ratio selections from 4.30 to 6.43.
- MX-120 High Retardation (HR) Series carrier with hypoid gearing and ratio selections of 4.88, 5.57, 6.14, and 6.43.
- Housing Wall Thickness: Available in various thicknesses, including 0.31 in (8 mm), 0.37/0.39 in (9.5/10.0 mm), 0.43 in (11 mm), 0.50/0.51 in (12.7/13.0 mm), and 0.56 in (14.3 mm).
- Optional Features: Includes High Retardation (HR) and Evolution - Lightweight designs (≤14,000 GAWR).
- Fastener Torque Specifications: Critical torque values are provided for various components, including wheel nuts (manufacturer's specifications), hubcap bolts (35-50 lb-ft), drive flange bolts (180-230 lb-ft), spindle and brake attachment capscrews (180-230 lb-ft), upper knuckle cap bolt/steering arm capscrew (500-650 lb-ft), brake chamber attachment nut (125-155 lb-ft), stop screw jam nut (75-100 lb-ft), tie rod end nut (160-215 lb-ft initial, 320 lb-ft max after assembly), tie rod clamp sleeve adjuster locknut (40-60 lb-ft), tie rod grease fitting (3.0 lb-ft), lower knuckle cap bolt (310-400 lb-ft), housing oil fill plug (35 lb-ft minimum), breather assembly (20 lb-ft minimum), housing drain plug (35 lb-ft minimum), spring plate bolt (100-115 lb-ft), carrier bolts (110-120 lb-ft), pinion nut (700-900 lb-ft), and hub oil fill/drain plug (51-59 lb-ft).
- Axle Lube Oil Capacity: 3.25 gallons (12.3 liters).
- Wheel Bearing End Play: Target range of 0.000-0.002-inch (0.025-0.051 mm).
- Steering Knuckle Rotational Torque: 8-25 lb-ft (20.8-33.9 Nm).
- Steering Knuckle Vertical End Play: 0.005-0.015-inch (0.127-0.381 mm).
- Tie Rod End Play: If movement is greater than 0.060-inch (1.52 mm), replacement is required.
- Camber Angle: Not adjustable; machined into the axle beam and knuckle. Meritor recommends +1/4 Nominal for unloaded axles and +3/16 to -3/16 (final reading) for loaded axles.
- Caster Angle: Not adjustable via the axle itself; controlled by housing pad angle or tapered shims under leaf springs. Meritor recommends +1 to +2-1/2 degrees for manual steering and +2 to +4-1/2 degrees for power steering.
- Toe-in/Toe-out: Adjustable. Sample recommendations vary based on front-drive axle use (frequent, normal, infrequent) and load (unloaded, loaded).
Usage Features:
- Automatic Slack Adjusters: Meritor automatic slack adjusters are included for brake maintenance.
- Hub-Piloted Design: Simplifies wheel mounting.
- ABS Integration: Pre-equipped for ABS, enhancing vehicle safety.
- Model Nomenclature: A detailed letter and number system identifies specific axle model features, including GAWR, axle model type, relative gearing size/series, housing wall thickness, optional features (HR, EVO), carrier variation, carrier type, wheel end/differential, brake type, and specification number.
Maintenance Features:
- Preventive Maintenance and Lubrication: Detailed guidelines are provided for regular checks and lubrication.
- Hazard Alert Messages: Comprehensive safety warnings are integrated throughout the manual, covering general safety, asbestos/non-asbestos fiber handling, and specific procedure-related risks.
- Cleaning Procedures: Instructions for cleaning parts, including ground/polished parts, rough parts, and axle assemblies, with specific warnings against certain cleaning agents and methods (e.g., compressed air for bearings, hot solution tanks for polished parts).
- Corrosion Prevention: Recommendations for applying light oil to cleaned parts and corrosion-preventive material for stored parts.
- Part Inspection: Thorough inspection procedures for tapered roller bearings (checking for wear, cracks, etching, pitting), axle housing (checking for cracks, loose studs, king pin bushings, thrust bearings, steering stops), axle shafts (checking for wear, stress, cracks, seals, bushings), and universal joints (checking for looseness).
- Lubricant Specifications: Meritor specifications (e.g., 0-76-A, 0-76-D) for gear oils (SAE 85W/140, 80W/90, 75W/90, 75W, 75W/140, 80W/90, 75W/85) are provided, along with recommended outside temperature ranges. Multi-purpose grease (Lithium 12-Hydroxy Stearate or Lithium Complex) is specified for king pins, camshaft bushings, and cross tube ends.
- Lubrication Intervals:
- Knuckle King Pins, Brake Camshaft Bushings/Seals, Cross Tube End Assembly: Every 3,000 miles (4800 km) or 200 hours, whichever comes first.
- Greased Wheel Bearings: On-Highway: 30,000 miles (48,000 km) or annually; On/Off-Highway: 15,000 miles (24,140 km) or twice a year.
- Spindle Axle Shaft Bushing: Every 100,000 miles (160,000 km) or 2 years.
- Axle Oil Change: Petroleum Oil: 25,000 miles (40,000 km) or annually; Synthetic Oil: 50,000 miles (80,000 km) or annually. For heavy-duty, check oil level every 1,000 miles (1600 km).
- EVO Wheel End Oil Change: 50,000 miles (80,000 km) or annually.
- Magnetic Drain Plugs: Axles are equipped with magnetic drain plugs with a minimum pickup capacity of 1.5 pounds (0.7 kg) of low carbon steel, to be inspected and cleaned during oil changes.
- Breather Maintenance: Baffle-type breathers help prevent moisture and dirt ingress; weekly inspection and cleaning recommended.
- Temperature Indicators: Tapped holes for lubricant temperature indicators are provided to help monitor oil temperature and prevent damage from overheating.
- Special Tools: Specific tool drawings are provided for fabricating an axle shaft seal driver, hub seal driver, and bushing driver.
- Adhesive and Silicone Gasket Material: Instructions for applying Loctite® and Permatex® products for secure assembly and sealing.
- Troubleshooting Guide: A comprehensive table lists common conditions (e.g., tire wear, hard steering, worn components), their causes, and recommended corrections.
Need help?
General
To Next Page
