The B&M Sport Shifter is a popular upgrade for Chevrolet Corvette C4 models equipped with the ZF 5-speed transmission. Known for its short throw and precise shifting action, this component can significantly enhance the driving experience. However, its installation is more involved than typical shifter upgrades, requiring careful attention to orientation, component alignment, and mechanical precision. This article provides a comprehensive, step-by-step guide based on a real-world installation experience shared by a user on CorvetteForum. The guide includes practical advice, potential pitfalls, and recommended tools, all derived directly from the original documentation.
Overview of the B&M Sport Shifter Installation
The B&M Sport Shifter is designed to offer a tighter, more responsive gear change than the factory unit. The installation process, however, is more complex than typical shifter upgrades. It involves removing the existing shifter, disassembling the transmission linkage, and installing new components such as the shifter base, pivot assembly, and spring pin. The user who documented this process noted that while each individual step is not overly difficult, the cumulative effort and spatial constraints under the vehicle make it a time-consuming and somewhat challenging task.
The installation requires a variety of tools, including both hand and power tools, and it is recommended that the vehicle be supported by a lift or jack to provide sufficient access to the rear of the car. The user emphasized the importance of working methodically, keeping track of small components like shims and bushings, and referencing the manufacturer’s instructions as a guide rather than a strict set of directions.
Preparing for the Installation
Before beginning the installation, it is essential to gather the necessary tools and materials. The user who documented the process listed the following tools as essential for the job:
- Bench vise
- Small flat blade screwdriver
- Long needle nose pliers
- Brake drum adjuster
- 3/8” Drive 7/16” Socket
- ½” Drive 13mm Socket
- ½” Drive 15mm Socket
- 3/8”-Drive 10mm Socket
- 3/8”-Drive 7mm Socket
- Side cutters
- Side post terminal wrench
- Cordless 3/8” Drive Impact Driver
- Cordless Drill
- ½” Drive ratchet
In addition to these tools, the user recommended using a soft jaw vise to protect delicate components during installation and disassembly. A clean microfiber towel was also used to lay out parts and prevent them from rolling away during assembly.
The user also emphasized the importance of reading through all instructions before beginning the installation. As with any automotive repair or modification, there is a risk of injury or damage, and the user explicitly stated that safety is the responsibility of the individual working on the vehicle. They also advised consulting the Factory Service Manual and the instructions that come with the B&M shifter kit for the most accurate and detailed guidance.
Removing the Factory Shifter
The first major step in the installation is removing the factory shifter. The user outlined several key steps to accomplish this, including:
Positioning the Vehicle: The rear of the car must be lifted to remove the exhaust and gain access to the shift linkage. The user used a Quickjack lift but noted that any method that provides stable and level support is acceptable.
Accessing the Shifter: Once the exhaust is removed, the shifter can be accessed from the bottom of the vehicle. The user moved the shifter gently to the 3rd gear position and noted that it would "pop" out of the gear slot. Wiggling and tugging upward helped to disengage the shifter from the transmission.
Handling Shims and Bushings: As the factory shifter was removed, the user observed that there were shims and nylon bushings at the ends of the shifter. These components may fall into the rubber boot, but they can be retrieved if necessary. The user noted the thickness of the shims (approximately 0.037” per end) and marked the nylon bushings to ensure they could be reinstalled in the correct orientation later.
Removing the Flange Bolt: The flange bolt that connects the shift rod adapter to the transmission can be difficult to remove due to a flared lip on the non-headed end. The user used a 9/32” drill bit to remove the flared portion before tapping the pin out with a hammer and drift. The shift rod adapter was re-used in the installation, so it was important to protect it during this process.
The user stressed the importance of working methodically during this phase, as the components involved are small and can easily be misplaced. Keeping track of parts, especially the shims and bushings, is crucial for reassembly later.
Assembling the B&M Shifter Components
Once the factory shifter was removed, the next step was to assemble the new B&M shifter components. The user provided a detailed breakdown of the assembly process, which included the following steps:
Laying Out Parts: The user laid out all the parts from the B&M kit on a clean microfiber towel according to the supplied diagram. This helped to ensure that all components were accounted for and that no parts were missing or misplaced.
Applying Grease: The user applied a small amount of lithium grease to the grooves of the lower bushing and to the four O-rings before installing them into the shifter. This helped to lubricate the moving parts and made the installation process smoother.
Installing the Spring Pin: One of the more critical steps in the assembly was installing the spring pin between the shifter bushing and the gear shift rod adapter. The user emphasized the importance of correct orientation. The opening of the ring on the lower shift rod should face downward as it faces the front of the car, and the slot in the threads of the shifter should face the rear. The user used a soft jaw vise to hold the assembly in place while pounding the pin in with a hammer and drift. They noted that the pin can be difficult to start but becomes easier once it is seated.
Adjusting the Brass Pins: The user measured the width of the brass pins on the new B&M shifter and compared it to the factory unit. The B&M measured 4.467”, while the factory unit was 4.321”. Because the new unit was slightly wider, the user had to adjust the brass pins by pounding them in to match the factory dimensions. After adjustment, the brass pins measured 4.392”, which was close enough to the factory width plus shims.
Installing the Spring Plate: After adjusting the brass pins, the user installed the spring plate over the shifter. They emphasized the importance of correct orientation—ensuring that the slot in the shifter threads faced the rear of the car and that the threads of the swing plate were aligned to the driver’s side. The user applied grease to the 3/8” pivot axle, inserted it into the assembly, and secured it with 5/16” acorn nuts on both ends. The nuts were tightened until the pin was seated and the assembly was snug but not overly tight.
The user noted that the assembly process required patience and attention to detail, particularly when it came to aligning the components and ensuring that the pivot points were properly lubricated. They also recommended using a drift to ensure that the spring pin was recessed equally on both sides, which helped to maintain balance and smooth operation.
Installing the Shifter into the Vehicle
After the B&M shifter components were assembled, the next step was to install the unit into the vehicle. The user outlined the following steps for this phase of the installation:
Positioning the Shifter: The user positioned the assembled shifter into the transmission housing, making sure that the orientation of the components matched the factory setup. They emphasized the importance of aligning the shifter correctly to ensure smooth operation and proper gear engagement.
Securing the Pivot Axle: The user inserted the 3/8” pivot axle into the shifter and secured it with 5/16” acorn nuts on both ends. They used a ½” wrench to tighten the nuts until the assembly was snug but not overly tight. The user noted that the movement should be smooth and free, but the assembly should not feel loose.
Reinstalling the Shift Rod Adapter: The user reinstalled the shift rod adapter into the transmission linkage, making sure that it was properly aligned with the new B&M shifter. They used the new spring pin provided in the kit to secure the adapter in place.
Adjusting the Shifter: Once the shifter was installed, the user adjusted the shift linkage to ensure that the gears engaged smoothly. They noted that the B&M shifter may require some fine-tuning, particularly if the brass pins were adjusted earlier in the process. The user recommended using shims to fine-tune the fit and ensure that the shifter operated without binding or resistance.
Reinstalling the Exhaust System: After the shifter was installed and adjusted, the user reinstalled the exhaust system and lowered the car from the lift. They checked for any leaks or misalignments and made any necessary adjustments before test driving the vehicle.
The user emphasized that the installation of the B&M shifter required patience and attention to detail, particularly when it came to aligning the components and ensuring that the shift linkage was properly adjusted. They also noted that the installation was more involved than typical shifter upgrades, but the improved shifting performance made the effort worthwhile.
Testing and Final Adjustments
Once the B&M shifter was installed and the exhaust system was reattached, the user performed a test drive to evaluate the performance of the new shifter. They noted that the B&M provided a much tighter, more responsive shift than the factory unit, which was the primary reason for the upgrade. The user also checked for any unusual noises or vibrations that might indicate a misalignment or improper installation.
The user made several final adjustments to the shift linkage, particularly to the brass pins and shims, to ensure that the gears engaged smoothly and without resistance. They also checked the pivot points for smooth operation and ensured that the nuts were properly tightened but not over-torqued.
Overall, the user was satisfied with the performance of the B&M shifter and noted that the installation was well worth the effort for the improved driving experience.
Conclusion
The B&M Sport Shifter is a popular upgrade for Chevrolet Corvette C4 models equipped with the ZF 5-speed transmission. While the installation process is more involved than typical shifter upgrades, the improved shifting performance and responsiveness make it a worthwhile investment for enthusiasts and DIY mechanics. The installation requires a variety of tools, careful attention to detail, and a methodical approach to ensure that all components are properly aligned and adjusted. By following the steps outlined in this guide, users can successfully install the B&M shifter and enjoy a more precise and responsive driving experience.