The Jeep Cherokee XJ, particularly the Series 1 models, are beloved for their ruggedness and off-road capabilities. However, their original transmissions can eventually wear out or become insufficient for modified vehicles. This guide will delve into the complexities of an XJ Series 1 transmission swap, providing valuable information for both seasoned mechanics and those tackling this project for the first time. We'll cover everything from choosing the right replacement to the challenges involved in the installation process.
Why Swap the Transmission?
Before diving into the specifics of a transmission swap, it's important to understand why someone would undertake such a project. Common reasons include:
- Transmission Failure: The original AX-15, while durable, is prone to failure, especially under heavy load or with modifications. A rebuild might be an option, but a swap offers a chance to upgrade to a stronger unit.
- Performance Upgrades: If you've significantly modified your engine (increased horsepower or torque), the stock transmission might not be able to handle the added power, leading to premature wear and tear.
- Improved Reliability: A newer or more robust transmission can provide enhanced reliability and longevity compared to an aging original.
- Gear Ratio Changes: Different transmissions offer various gear ratios, potentially improving fuel economy, towing capacity, or off-road performance depending on your needs.
What Transmissions Can I Swap Into My XJ Series 1?
This is arguably the most crucial decision. Many options exist, each with its own advantages and disadvantages. Popular choices include:
- AX-15 (from later XJ models): While still an AX-15, later models offered slight improvements in design. A direct swap might be possible, but careful inspection and potential modifications might be needed.
- NV3550: A stronger and more robust five-speed manual transmission often found in other Jeep models and even some Dodge trucks. This is a popular choice for increased durability and capability, although it requires more significant modifications for installation.
- AW4 Automatic: An automatic option that provides convenience and can handle moderate power increases. However, an AW4 swap necessitates significant modifications, including potentially adapting the transfer case.
Choosing the Right Transmission: Factors to Consider
The best transmission for your XJ Series 1 will depend on your specific needs and budget. Factors to consider include:
- Your budget: Some transmissions are significantly more expensive than others, both in terms of purchase price and installation costs.
- Your driving style: A performance-oriented transmission might be overkill if you primarily use your XJ for light off-roading or daily driving.
- Your vehicle's modifications: If you have significant engine modifications, you need a transmission that can handle the increased power and torque.
What are the Common Challenges of an XJ Series 1 Transmission Swap?
Swapping a transmission isn't a simple bolt-on affair. You'll likely encounter the following challenges:
- Modified Driveshaft: The length of the driveshaft will likely need adjusting to accommodate the new transmission's location.
- Transfer Case Adapters: Depending on the chosen transmission and your current transfer case, you might need an adapter to ensure compatibility.
- Clutch Linkage/Shifter Linkage: Modifying the clutch linkage and shifter linkage to fit the new transmission may be necessary.
- Wiring (Automatic Transmissions): If going with an automatic, expect significant modifications to the wiring harness and potentially additional electrical components.
How Difficult is an XJ Series 1 Transmission Swap?
The difficulty varies considerably depending on your experience level and the chosen transmission. A simple AX-15 swap from a later model might be manageable for a moderately experienced mechanic. However, swapping in an NV3550 or AW4 is a significantly more complex project demanding advanced mechanical skills and potentially specialized tools.
What Tools and Parts Will I Need for an XJ Series 1 Transmission Swap?
This list is not exhaustive, but highlights essential items:
- Jack and Jack Stands: For safely lifting and supporting the vehicle.
- Transmission Jack: For safely supporting the transmission during installation and removal.
- Torque Wrench: For tightening bolts to the correct specifications.
- Various Sockets and Wrenches: A comprehensive set is essential.
- New Transmission: Obviously!
- New Clutch (Manual Transmissions): Highly recommended for a manual transmission swap.
- Necessary Adapters and Shifter Linkage: Depending on the swap.
- Transmission Fluid: The correct type and amount.
This guide provides a general overview. Consult a reputable repair manual specific to your XJ Series 1 model and chosen transmission for detailed instructions. Remember that this project can be challenging, so careful planning, preparation, and potentially professional assistance are recommended. Remember safety first!
