Dana 60 Axle Performance Guide - Square Body Trucks

Overview

The Dana 60 front axle was the heavy-duty option for 1973-1987 GM Square Body trucks, primarily found in K20 and K30 models, as well as some heavy-duty K10 configurations. This full-floating front axle assembly was designed for serious hauling and towing applications, offering superior strength compared to the more common Dana 44. For Square Body owners looking to maximize towing capacity, handle heavy loads, or build a robust off-road machine, understanding Dana 60 performance optimization is crucial.

The Dana 60 features a 9.75" ring gear diameter and was available in both open differential and limited-slip configurations. GM paired this axle with the NP205 or NP208 transfer cases, creating a drivetrain capable of handling substantial abuse. Performance modifications can significantly increase the axle's capability while maintaining reliability.

Common Issues

Ring and Pinion Wear

• Symptoms: Whining noise during acceleration or deceleration, particularly noticeable at highway speeds
• Causes: High mileage, improper setup, or insufficient lubrication
• Inspection: Look for scoring on gear teeth, excessive backlash (should be 0.005"-0.009")

Ball Joint Deterioration

• Symptoms: Wandering steering, clunking over bumps, uneven tire wear
• Critical Points: Upper and lower ball joints on both sides, particularly problematic on 1973-1980 models
• Safety Note: Worn ball joints can cause catastrophic steering failure

Unit Bearing Failures

• Symptoms: Grinding noise from wheels, play in wheel assembly, ABS warning lights (if equipped)
• Common on: 1981-1987 models with unit bearing assemblies
• Replacement Interval: Typically 100,000-150,000 miles depending on use

Differential Carrier Issues

• Open Differential Wear: Side gear and spider gear wear from heavy use
• Limited-Slip Problems: Clutch pack wear causing one-wheel drive scenarios
• Bearing Failures: Carrier bearings failing due to high loads or age

Parts & Materials Needed

Performance Ring and Pinion Sets

• Yukon Gear YG D60-456: 4.56:1 ratio for improved torque multiplication
• Richmond Gear 69-0060-1: 4.10:1 ratio for balanced performance and economy
• Motive Gear D60-373: 3.73:1 ratio for highway driving with larger tires

Differential Upgrades

• Eaton Truetrac 913A582: Helical limited-slip differential
• ARB RD117: Air-activated locking differential
• Yukon Dura Grip YGLD60-4-30: Clutch-type limited-slip

Axle Shaft Upgrades

• Yukon YA D52146-30: 30-spline chromoly axle shafts (1973-1979)
• Spicer 44593: OEM replacement 30-spline shafts
• Ten Factory MG27140: Upgraded 35-spline conversion kit

Essential Tools and Materials

• Bearing Puller Set: OTC 4579 or equivalent
• Dial Indicator: For backlash measurement
• Inch-Pound Torque Wrench: For pinion preload setting
• Gear Oil: 80W-90 conventional or synthetic (3.5-4 quarts)
• Limited-Slip Additive: If using clutch-type differential
• RTV Silicone: Permatex Ultra Black for gasket sealing

Step-by-Step Performance Guide

Ring and Pinion Installation

Preparation

1. Remove axle assembly from vehicle using appropriate jack stands and safety procedures
2. Drain gear oil completely and inspect for metal particles
3. Remove differential cover and mark bearing caps for reassembly
4. Extract carrier assembly using appropriate pullers

Pinion Setup

1. Remove old pinion gear and clean housing thoroughly
2. Install new pinion bearings using bearing driver set
3. Set pinion depth using pinion depth gauge tool:
   - Install gauge block in carrier bore
   - Measure distance from mounting face to gauge block
   - Adjust shim thickness accordingly (typically 0.025"-0.035")
4. Install pinion gear with calculated shim pack
5. Set pinion preload to 25-35 inch-pounds for new bearings

Ring Gear and Carrier Setup

1. Mount new ring gear to carrier using:
   - Torque specification: 140 ft-lbs in cross pattern
   - Thread locker: Loctite 271 on all bolts
2. Install carrier assembly in housing
3. Set backlash to 0.005"-0.009" using adjusting nuts
4. Check contact pattern using gear marking compound:
   - Correct pattern: Centered on tooth face, covering 50-60% of tooth
   - Adjust as needed: Modify pinion depth or backlash

Differential Upgrade Installation

Limited-Slip Installation

1. Prepare carrier case ensuring clean, smooth surfaces
2. Install side gears with appropriate thrust washers
3. Install clutch packs (if applicable):
   - Clutch clearance: 0.030"-0.050" total
   - Preload: Follow manufacturer specifications
4. Install spider gears and cross shaft
5. Apply gear oil and limited-slip additive as specified

Locking Differential Installation

1. Mount air line fitting through axle housing (ARB units)
2. Install differential assembly following manufacturer torque specifications
3. Route air lines to compressor location
4. Install activation switch in cab
5. Test operation before final assembly

Year/Model Differences

1973-1980 Models

• Ball Joint Type: Serviceable upper and lower ball joints
• Axle Shaft Spline: 30-spline standard
• Brake System: Drum brakes standard, disc brake option available
• Steering: Manual steering standard, power steering optional
• Hub Assembly: Serviceable wheel bearings in traditional hubs

1981-1987 Models

• Ball Joint Type: Sealed ball joints, upper often integrated with control arm
• Unit Bearings: Sealed unit bearing assemblies replace serviceable hubs
• Brake System: Disc brakes more common, improved caliper designs
• CV Joints: Some applications use CV joints instead of traditional U-joints
• Electronic Integration: Later models may have ABS sensors

Model-Specific Applications

K20 (3/4 Ton)

• Standard Configuration: Dana 60 front, 14-bolt rear
• Gear Ratios: 3.73:1 or 4.10:1 most common
• Load Rating: 6,200 lb GVWR typical

K30 (1 Ton)

• Heavy-Duty Setup: Dana 60 front, full-floating 14-bolt rear
• Gear Ratios: 4.10:1 or 4.56:1 standard
• Load Rating: 8,600-10,000 lb GVWR

Suburban/Blazer Applications

• Gear Ratio Preference: 3.73:1 for highway driving
• Differential Type: Open differential most common
• Special Considerations: Longer wheelbase affects driveline angles

Tips & Best Practices

Performance Optimization

• Gear Ratio Selection:
• 3.73:1 for highway driving with 31"-33" tires
• 4.10:1 for balanced performance with 33"-35" tires
• 4.56:1 for heavy towing or 35"+ tires
• Differential Choice: Truetrac for street/light off-road, ARB for serious off-road use
• Lubrication: Synthetic 75W-90 for improved performance and longevity

Installation Best Practices

• Always replace bearings when installing new gears
• Use proper torque sequence on ring gear bolts (star pattern, three stages)
• Break-in procedure: First 500 miles with conventional oil, then switch to synthetic
• Pattern checking is critical: Poor contact patterns cause premature failure

Common Mistakes to Avoid

• Insufficient pinion preload: Causes bearing failure and gear whine
• Incorrect backlash: Too tight causes binding, too loose causes noise
• Reusing old hardware: Ring gear bolts and crush sleeves should always be new
• Mixing gear oil types: Don't mix conventional and synthetic without complete drain

Vendor Recommendations

• LMC Truck: Complete axle rebuild kits and OEM replacement parts
• Classic Industries: Performance upgrades and restoration components
• Randy's Ring & Pinion: Professional gear sets and installation kits
• Yukon Gear: Complete drivetrain packages for performance builds

Troubleshooting

Gear Whine Diagnosis

Highway Speed Whine (Acceleration)
- Cause: Pinion depth too shallow or insufficient backlash
- Solution: Reset pinion depth, check backlash specification

Highway Speed Whine (Deceleration)
- Cause: Pinion depth too deep or excessive backlash
- Solution: Add pinion shims, reduce backlash

Low Speed Rumble
- Cause: Differential bearing preload issues
- Solution: Check carrier bearing preload, replace if necessary

Handling Issues

Steering Wander
- Check: Ball joint wear, wheel bearing play, tire pressure
- Test: Jack up front end, check for play in all joints

Vibration Under Load
- Inspect: U-joint condition, driveshaft balance, motor mounts
- Verify: Proper driveline angles after any suspension modifications

Differential Problems

Limited-Slip Not Engaging
- Causes: Worn clutch packs, wrong gear oil, insufficient additive
- Solutions: Replace clutch packs, use proper limited-slip additive

Locking Differential Won't Engage
- Check: Air pressure (ARB), electrical connections, actuator function
- Test: System pressure should be 90+ PSI for reliable operation

Maintenance Intervals

• Gear Oil Change: Every 30,000 miles normal use, 15,000 miles severe service
• Ball Joint Inspection: Every 12,000 miles or annually
• U-Joint Lubrication: Every 5,000 miles or per manufacturer schedule
• Differential Additive: Add limited-slip additive every other oil change

This comprehensive guide provides the foundation for optimizing Dana 60 performance in Square Body trucks. Whether building for heavy towing, off-road capability, or simply maintaining this robust axle assembly, following these procedures will ensure reliable operation and maximum performance.