The Jeep Cherokee XJ, particularly the Series I models (1984-1986), are beloved for their ruggedness and off-road capabilities. However, their original transmissions, often the AX-15, can suffer from wear and tear, especially after years of demanding use. This guide delves into the complexities and considerations involved in swapping the transmission on an XJ Series I, addressing common concerns and offering practical advice. While specific procedures may vary slightly depending on the year and model, the fundamental principles remain the same.
Why Swap Your Transmission?
Several reasons might lead you to consider a transmission swap for your XJ Series I:
- Failure of the Original Transmission: Worn synchros, shifting problems, or complete failure necessitate a replacement.
- Performance Upgrades: A stronger, more robust transmission can handle increased torque from engine modifications.
- Reliability Improvements: Upgrading to a later model transmission can offer improved durability and longevity.
- Specific Gear Ratios: A different transmission might provide more favorable gear ratios for specific driving conditions (e.g., rock crawling, towing).
What Transmissions Are Compatible?
Several transmissions can be adapted for an XJ Series I swap, though some require more extensive modifications than others. The most common choices include:
- AX-15 (Later Model): While the original AX-15 is prone to issues, finding a well-maintained one from a later XJ (post-1987) could be a viable and relatively straightforward swap. These later versions often incorporate improvements over the Series I units.
- AW-4 (Automatic): Switching to an automatic AW-4 transmission involves more significant modifications due to differences in bellhousing, control systems, and drivetrain components. However, it offers the convenience of automatic shifting.
- NV3550: Found in some later Jeep models and other vehicles, this manual transmission is a popular upgrade, offering improved strength and reliability. However, it requires more extensive adaptation, potentially including custom bellhousing fabrication or modification.
What are the common challenges of an XJ Series I transmission swap?
This section addresses frequently asked questions related to XJ Series I transmission swaps, drawing from extensive experience and research within the Jeep community.
What is the most difficult aspect of an XJ transmission swap?
The difficulty varies drastically depending on the chosen transmission. Swapping an AX-15 for another AX-15 is relatively straightforward for someone with mechanical experience, mainly involving removing the old unit, installing the new one, and bleeding the clutch system. However, moving to a completely different transmission, such as the AW-4 or NV3550, will present significant challenges. These often necessitate custom parts, modifications to the transmission tunnel, and potentially adjustments to the driveshaft and linkage. Precise alignment and proper torque specifications are critical to avoid transmission or drivetrain damage.
What tools and equipment will I need?
This will depend on the specific transmission being swapped, but generally expect to need a comprehensive set of tools including: transmission jack, engine hoist, torque wrench, socket set, various wrenches, and potentially specialized transmission tools. Access to a repair manual specific to your XJ model and the chosen transmission is highly recommended.
How much will a transmission swap cost?
Costs vary considerably. A simple AX-15-to-AX-15 swap might cost relatively little if you source a used transmission and perform the labor yourself. However, a more involved swap with an AW-4 or NV3550 will add significant expenses due to the required parts, potentially including custom fabrication. Labor costs will also increase dramatically. Always factor in potential unforeseen issues and the price of new or used parts.
Can I do this myself, or do I need professional help?
While some straightforward swaps are possible for experienced mechanics, complex transmission swaps are best left to professionals, especially those unfamiliar with working on automotive transmissions. Improper installation can result in significant damage to the vehicle and its components.
Where can I find a replacement transmission?
Used transmissions can be found through online marketplaces like eBay and Craigslist, salvage yards, and Jeep-specific forums. New transmissions are available from dealerships or transmission specialists, but will typically be a more expensive option.
Conclusion
Swapping a transmission in an XJ Series I can significantly improve its performance and reliability. However, it is a complex undertaking requiring mechanical knowledge, the right tools, and careful planning. Choose the right transmission for your needs and budget, and always seek professional help if you lack the necessary experience. Proper installation is key to preventing further damage and ensuring years of trouble-free operation.
