1988 Jeep MJ Cherokee 5 Speed Transmission Manual

The 1988 Jeep MJ Cherokee features a rugged 5-speed manual transmission designed for optimal performance in both on-road and off-road conditions. This manual transmission system provides precise gear control, durability, and enhanced driving experience for the classic Jeep Comanche pickup. Below are key sections covering specifications, operation, maintenance, troubleshooting, and service procedures.

1. Transmission Specifications 2. Gear Ratios and Operation 3. Clutch System 4. Fluid Requirements 5. Shift Pattern and Operation 6. Maintenance Schedule 7. Troubleshooting Common Issues 8. Transmission Removal and Installation 9. Safety Precautions 10. Warranty and Support

Transmission Specifications

The 5-speed manual transmission in the 1988 Jeep MJ Cherokee is engineered for durability and smooth shifting performance.

Specification	Details
Transmission Model	Aisin-Warner AX5 5-speed manual
Gear Ratios	1st: 3.93, 2nd: 2.33, 3rd: 1.45, 4th: 1.00, 5th: 0.85, Reverse: 4.74
Fluid Capacity	3.5 quarts (3.3 liters)
Fluid Type	GL-5 75W-90 Gear Oil
Case Material	Aluminum alloy
Weight	Approximately 75 lbs (34 kg)
Input Shaft	10 spline, 1-1/16" diameter
Output Shaft	27 spline
Shift Linkage	Direct mechanical linkage

Gear Ratios and Operation

Understanding the gear ratios and proper shifting techniques for optimal performance.

1st Gear (3.93:1): For heavy loads and steep inclines
2nd Gear (2.33:1): General acceleration and city driving
3rd Gear (1.45:1): Highway entry and moderate speeds
4th Gear (1.00:1): Direct drive for fuel efficiency
5th Gear (0.85:1): Overdrive for highway cruising
Reverse (4.74:1): Low gear ratio for controlled reversing

WARNING! Always depress clutch fully when shifting. Do not force gears.

Clutch System

The hydraulic clutch system works in conjunction with the 5-speed transmission.

Clutch Type: Single dry disc, diaphragm spring
Clutch Fluid: DOT 3 Brake Fluid
Clutch Pedal Free Play: 1/2 to 1 inch (12-25mm)
Master Cylinder Bore: 0.75 inches
Slave Cylinder Bore: 0.875 inches

CAUTION! Check clutch fluid level regularly. Air in system causes poor shifting.

Fluid Requirements

Recommended Fluid: GL-5 75W-90 Gear Oil
Capacity: 3.5 quarts (3.3 liters)
Change Interval: Every 30,000 miles or 2 years
Drain Plug: 3/8" square drive, magnetic
Fill Plug: 3/8" square drive, located on driver side
Inspection: Check for metal particles on drain plug

Shift Pattern and Operation

Standard H-pattern shift configuration with reverse lock-out.

Shift Pattern:

    R   1   3   5
    ┌───┬───┬───┐
    │   │   │   │
    ├───┼───┼───┤
    │   │   │   │
    └───┴───┴───┘
    2   4

Operation Tips: Smooth clutch engagement, rev-match downshifts, avoid riding clutch. Reverse requires lifting collar on shift knob.

Maintenance Schedule

Regular maintenance ensures longevity and optimal performance.

Every 5,000 miles: Check transmission fluid level
Every 15,000 miles: Inspect shift linkage and bushings
Every 30,000 miles: Change transmission fluid
Every 60,000 miles: Inspect clutch components
As needed: Adjust clutch pedal free play

Tip: Use only recommended fluids to prevent premature wear.

Troubleshooting Common Issues

Symptom	Possible Cause	Corrective Action
Difficulty shifting	Low fluid, worn synchronizers	Check fluid level; inspect synchronizers
Grinding noises	Worn clutch, low fluid	Adjust clutch; check fluid level
Jumping out of gear	Worn detents, shift forks	Inspect shift mechanism; replace worn parts
Fluid leaks	Worn seals, loose bolts	Replace seals; tighten case bolts
Vibration in gear	Worn U-joints, input shaft	Inspect driveline components

Transmission Removal and Installation

Step-by-step procedure for transmission removal and installation.

Disconnect battery negative terminal
Remove shift lever and boot
Support transmission with jack
Disconnect driveshaft and clutch linkage
Remove crossmember and exhaust components
Lower transmission carefully
Reverse procedure for installation

WARNING! Transmission is heavy; use proper lifting equipment.

Safety Precautions

Always follow safety procedures when working on transmission.

CAUTION! Work on level surface with parking brake engaged. Wear safety glasses. Hot transmission components can cause burns.

Warranty and Support

Original warranty coverage and technical support information.

Original warranty: 12 months/12,000 miles. For technical support, contact Jeep Customer Service at 1-800-925-JEEP or visit authorized Jeep dealerships. Replacement parts available through Mopar®.