MMD 5-Speed Reverse Gear Installation and Components

The MMD 5-Speed Reverse Gear is an aftermarket component designed to add reverse functionality to Harley-Davidson motorcycles, particularly those used with sidecars or trikes. The system comprises mechanical and electrical components requiring careful installation, ideally performed by a qualified professional. The reverse gear is constructed with aircraft-grade aluminum and hardened steel gears for durability and is available for both 5-speed and 6-speed transmissions. A built-in safety feature automatically shuts off the engine if forward gears are engaged while in reverse. Installation involves modifications to the transmission, including gear replacement and wiring for the activation switch.

System Overview and Applications

The MMD Reverse Gear addresses the need for maneuverability in heavier motorcycle configurations, such as trikes, where backing up can be challenging. The documentation highlights its suitability for trikes weighing up to 800lbs. The system is designed to provide full control and peace of mind when maneuvering in tight spaces or backing out of parking areas. The reverse gear kit is intended for use with both EVO and Twin Cam Harley-Davidson motorcycles equipped with 5-speed transmissions, though a 6-speed version is also available.

Component Parts List

The MMD 5-Speed Reverse Gear kit includes a specific set of components, as detailed in the provided parts list. These include:

RG-001-100: Housing, aluminum assembly (RG3)
RG-000-002: Gear, large, counter shaft
RG-000-003: Gear, small, main shaft
RG-000-008: Ring, split (x2)
RG-000-009: Nut, lock, bearing (x2)
RG-000-029: Ring, "O", cable, clutch, No. 011
SE-K00-001: Gasket, transmission case
SE-K00-002: Gasket, clutch cover
RG-000-015: Tool, ring, lock
RG-000-016: Tool, driver, hex
RG-000-023: Spring, for tool
RG-101-020: Compound, thread, assembly, RG3/RG
Hardware Kit: Includes washers (shim, flat, wavy, crush, nylon) and set screws.
RG-000-030: Washer, shim, flat (x24)
RG-000-021: Washer, wavy (x2)
RG-000-032: Washer, crush, nylon (x2)
RG-000-033: Screw, set, nylon (x5)
RG-000-031: Gauge, feeler, 3/16" x 2" x ".

Additionally, the kit includes instructions and a warranty card.

Installation Procedure – Mechanical Aspects

The installation process requires several mechanical steps. First, the transmission bearing housing must be removed, often requiring a puller. This housing is replaced with a new “Trap Door” style housing provided in the kit. Before proceeding, it is crucial to cover exposed gears within the transmission with a cloth to prevent damage.

The installation involves replacing the existing main and countershaft gears with new gears supplied in the kit. It is essential to note that these gears are factory-matched sets and should not be mixed. The shifter fork rod must be marked flush at the transmission case and then pulled out approximately 1/4 inch.

During assembly, it is important to ensure the OEM dowel pins are in place within the transmission casing. The bearing lock nut and wavy washers are initially used as tools to seat the housing bearing against the shoulder of the new gear and are permanently installed in a later step. The countershaft shoulder should be flush with the gear face, while the main shaft gear will overhang the shoulder slightly.

Torque specifications are critical. The ring seat tool should be torqued to 40 ft-lbs after applying thread-locking compound to the tapered split ring and the new countershaft gear. The outside face of the tapered lock ring must be at least 1/2 inch recessed below the outside face of the new gear.

Installation Procedure – Electrical Aspects

The documentation references the need for electrical setup, though specific details are limited. The MMD Reverse Gear incorporates a built-in safety engine shut-off switch, which prevents engagement of forward gears while the reverse gear is active. This requires wiring the relay and switch as indicated in the provided diagrams. The documentation does not detail the specifics of the wiring diagram beyond its inclusion as a visual aid.

Important Considerations and Cautions

Several cautions are highlighted in the installation instructions. It is crucial not to pull the shifter fork rod out of the transmission more than 1/4 inch. Additionally, the tapered split rings are factory-matched sets and must not be mixed. The use of thread-locking compound on specific components is also emphasized. The documentation also notes the importance of using a new transmission bearing housing.

User Feedback and Related Issues

A forum post indicates a user seeking an installation DVD for the MMD reverse gear, suggesting that a video guide may be available. Another user reported fitting the MMD reverse gear to a 1993 FLHR Harley-Davidson and planned to provide a review upon completion. This user also encountered issues sourcing replacement parts for a sidecar installation, specifically a brake line and sender piece. A solution for modifying the pannier latch to prevent interference with a sidecar was also requested, with a response suggesting a replacement hinge is available from the sidecar manufacturer.

Component Specifications

The MMD Reverse Gear is constructed with specific materials to ensure durability and performance:

Body: Aircraft-grade aluminum
Gears: Hardened steel

These materials contribute to the gear’s ability to handle the demands of heavy trikes without adding excessive weight.

Safety Features

A key feature of the MMD Reverse Gear is the integrated safety engine shut-off switch. This switch prevents the rider from accidentally engaging forward gears while the reverse gear is activated, minimizing the risk of damage to the transmission.

Conclusion

The MMD 5-Speed Reverse Gear provides a solution for adding reverse functionality to Harley-Davidson motorcycles, particularly those equipped with sidecars or trikes. Installation requires careful attention to detail, adherence to torque specifications, and proper wiring of the safety shut-off switch. The system’s construction with aircraft-grade aluminum and hardened steel gears ensures durability, while the integrated safety feature enhances operational safety. Professional installation is recommended to ensure correct functionality and prevent potential damage to the motorcycle’s transmission.

Sources

The provided source material is insufficient to produce a 2000-word article. Below is a factual summary based on available data.