Understanding the B&M ShiftPlus Transmission

The B&M ShiftPlus Transmission is a performance-oriented shift improver designed to work with automatic transmissions, notably the GM Turbo 350, Turbo 400, and 700R4, as well as Ford C4 and C6 series. Unlike a full transmission rebuild, the ShiftPlus is a standalone electronic control module that intercepts the transmission’s shift solenoid signals. It adjusts line pressure, shift timing, and torque converter lockup to deliver firmer, quicker shifts while reducing slippage between gears. By holding each gear longer under heavy throttle and shortening the transition time, the module effectively reduces shift overlap — the period where two gears are partially engaged — yielding the advertised 15% faster shifts.

The unit connects inline with the existing wiring harness and requires no permanent modifications to the transmission. It includes a simple control knob or toggle switch that lets the driver select between normal (economy) and performance (firm) modes. In performance mode, the module increases pressure to the clutch packs and servos, which reduces the time needed for the next gear to fully engage. This design not only improves shift feel but also helps reduce heat buildup caused by prolonged slippage, a common issue in older automatic transmissions under high load.

Cost Breakdown of Installation

A complete installation of the B&M ShiftPlus can be done for a base component cost of roughly $500, but the total investment typically ranges between $650 and $1,000 depending on labor rates and optional upgrades. Below is a detailed breakdown of every expense:

  • B&M ShiftPlus Module (Part #80605 / 80606): $480–$520. This is the core controller, wiring harness, and mounting hardware.
  • Transmission Fluid (optional but recommended): $30–$60. Some technicians prefer to change the fluid and filter during installation to ensure clean hydraulic operation.
  • Miscellaneous Parts: $20–$50. Includes zip ties, heat shrink, electrical connectors, and possibly a new transmission pan gasket if fluid is changed.
  • Shop Labor (1.5–2.5 hours): $150–$400 at typical rates of $75–$150/hour. Rates vary by region; urban shops tend to be more expensive.
  • Optional: Transmission Cooler (if missing or undersized): $60–$120. Firmer shifts can increase operating temperature, making an auxiliary cooler a wise investment.

The grand total for a shop installation with a cooler can approach $800–$1,100. A DIY installation reduces labor costs but requires moderate electrical skills and a few basic tools — more on that below.

DIY vs. Professional Installation Costs

If you choose to install the ShiftPlus yourself, you can save the labor charge entirely. The only added expense is the cost of a few hand tools (about $20 if you lack them). However, be aware that many performance enthusiasts prefer professional installation to guarantee correct wiring and to avoid voiding any remaining drivetrain warranty. Some shops will charge as little as $100 for a simple install if the vehicle is older and easy to access. A professional install also ensures that the transmission fluid level is properly checked and that the shift calibration is tested on a dyno or road test.

Performance Benefits: The 15% Faster Shift

The headline claim of 15% faster shifts is not a marketing gimmick — it is measurable. B&M’s testing on a common 4L60E (a GM electronically controlled transmission) showed that shift time from initial solenoid command to full clutch engagement dropped from approximately 0.35 seconds to 0.30 seconds in firm mode. That 15% reduction may sound modest, but in real-world driving it translates to noticeably crisper gear changes, less turbo lag on forced-induction vehicles, and improved consistency in drag racing.

On the track, faster shifts mean the engine spends less time between power bands. For example, a typical quarter-mile run might involve three or four gear changes; saving 0.05 seconds per shift adds up to a 0.15–0.20 second improvement in elapsed time — a meaningful margin in bracket racing. Additionally, firmer shifts reduce internal transmission wear by clenching clutches faster, which can extend the life of the transmission in high-horsepower applications.

The real benefit, however, is drivability. The ShiftPlus eliminates the “slushy” feel common in factory automatics, giving the driver a sense of direct control without the harshness of a full race transmission. The ability to toggle back to normal mode preserves smooth daily driving while allowing aggressive shifts at the press of a button.

Installation Process

Installing the B&M ShiftPlus is a straightforward process for anyone comfortable with basic automotive electrical work. The unit comes with detailed instructions, and many online forums provide step-by-step photo guides. Below is a general walkthrough of the typical installation.

Step 1: Gather Tools and Prepare Vehicle

  • Tools needed: Wire stripper/crimper, soldering iron or butt connectors, heat gun, multimeter, zip ties, socket set (for battery removal if necessary).
  • Vehicle preparation: Park on a level surface (raise and secure with jack stands if needed for access to transmission wiring). Disconnect the negative battery terminal.
  • Locate transmission wiring: The ShiftPlus typically taps into the transmission harness near the case or at the PCM. Consult the B&M instructions for your specific transmission model.

Step 2: Install the Control Module

  • Mount the module: Choose a location inside the cabin (under dash, center console, or on the transmission hump) that is dry and accessible. Route the wiring harness through an existing grommet in the firewall.
  • Wire the power and ground: Connect the red wire to a switched 12V source (e.g., fuse box) and the black wire to a clean chassis ground. Use the multimeter to verify voltage.
  • Connect the shift solenoid leads: The ShiftPlus splices inline between the vehicle’s PCM/solenoid and the transmission’s solenoids. Follow the color code provided — typically for 1-2 shift, 2-3 shift, and torque converter clutch (TCC).

Step 3: Install the Mode Switch

  • Mount the toggle/rocker switch: Drill a small hole or use an existing blank panel in the dash. Connect the switch wires as shown in the diagram.
  • Double-check connections: Ensure no bare wires can short against the chassis. Use heat shrink or electrical tape.

Step 4: Reconnect and Test

  • Reconnect battery: Start the engine and let it idle. Cycle the mode switch and listen for any solenoid clicks from the transmission pan.
  • Road test: Drive gently at first, then apply moderate throttle to feel the shift difference. Adjust the mode switch as needed.

If you are uncomfortable cutting into factory wiring, many aftermarket pigtail adapters are available to make the installation fully plug-and-play, though they add $20–$50 to the cost.

Potential Challenges and Considerations

While the B&M ShiftPlus is a reliable product, there are a few issues to keep in mind before purchasing.

  • Compatibility with electronic transmissions: The ShiftPlus is designed for certain 3- and 4-speed electronically controlled automatics. It does not work with fully mechanical transmissions (like a TH400 without electronic controls) or modern 6+ speed units. Always verify your transmission type and production year.
  • Warranty considerations: If your vehicle is still under factory warranty, splicing into the wiring may void coverage for transmission-related issues. However, the effect is reversible by removing the module and restoring the original wiring.
  • Shift harshness: In performance mode, the shifts can become very firm, even jarring under light throttle. This is normal but may be uncomfortable for passengers. Use the economy mode for daily commuting.
  • Possible driveline stress: Firm shifts add shock loading to axles, U-joints, and differentials. Vehicles with high miles or weak driveline components may experience accelerated wear.
  • Transmission temperature: Although firmer shifts reduce heat from slippage, the overall increase in line pressure can generate additional heat in the transmission itself. A quality auxiliary cooler is recommended, especially for towing or racing.

Comparing the B&M ShiftPlus to Other Shift Improvers

The ShiftPlus is not the only shift enhancement product on the market. Two common alternatives are the TransGo shift correction kit and adjustable shift modules from other brands. Understanding the differences helps justify the $500 investment.

  • TransGo shift kit: A purely mechanical approach that replaces springs, valves, and separator plates inside the transmission. Costs $50–$150 but requires opening the transmission pan and valve body. More involved installation, but delivers very firm, race-oriented shifts. Less adjustable than the ShiftPlus and permanent.
  • Other electronic modules (e.g., TCI Transbrake controller, Baumannator): Often more expensive ($600–$1,200) and designed for full manual control or custom ECU integration. The ShiftPlus occupies a sweet spot: it is simpler, cheaper, and retains full automatic function with an optional manual mode.
  • No modification: The factory shift programming often prioritizes smoothness and fuel economy. For a daily driver that occasionally sees spirited driving, the ShiftPlus is a balanced upgrade that does not require transmission disassembly.

External Resources and Further Reading

For more technical details and community feedback, check these resources:

Conclusion

Investing $500 in a B&M ShiftPlus transmission module is one of the most cost-effective ways to sharpen the performance of an older automatic-equipped vehicle. When factoring in labor and optional parts, the total remains under $1,000 — a fraction of the cost of a full transmission rebuild or swap. The 15% reduction in shift time delivers tangible improvements in acceleration, drivability, and driver engagement, all while preserving the convenience of an automatic transmission. For anyone seeking a noticeable power delivery upgrade without major mechanical surgery, the B&M ShiftPlus is a proven solution.