The debate between retaining a side-shift gearbox and upgrading to a center-shift configuration is common among classic British car enthusiasts. For those considering a shift gearbox upgrade, this article explores the options available, focusing on the pros and cons of each.
Side-Shift Gearbox with Upgrades
Retaining the original side-shift gearbox with a higher overdrive (28 percent) offers a more straightforward approach. This involves sourcing upgraded internal components from reputable suppliers like Denis Welch Motorsport or AH Spares. This path often proves less labor-intensive and potentially more cost-effective than a complete transmission swap. Focus on replacing wear items with high-quality replacements to ensure longevity and improved performance. Key components to consider upgrading include gears, synchromesh components, and bearings.
Center-Shift Gearbox Conversions: Tremec vs. Smitty
Converting to a center-shift gearbox requires significantly more effort and investment but ultimately delivers a more modern driving experience. Two popular conversion kits dominate the market: the Tremec kit from The Driven Man and the Smitty kit utilizing a Toyota W58 transmission.
The Tremec kit offers a complete package including a brand-new, robust Tremec transmission with a higher overdrive ratio than even the upgraded side-shift option. While this kit carries a higher initial cost (over $5,000), it includes free shipping and eliminates the need to source a used transmission.
The Smitty kit, centered around the Toyota W58 transmission, presents a potentially more budget-friendly alternative. However, this kit requires sourcing a used W58 transmission independently. Finding a suitable transmission in good condition is becoming increasingly challenging, adding complexity and potential rebuild costs to the project.
Both the Tremec and Smitty conversions demand significant mechanical skill and often necessitate fabrication and problem-solving during installation. Regardless of the chosen kit, the result is a significantly stronger transmission with the convenience of fully synchronized gears, including first gear.
Rebuilding Your Existing Gearbox
For those prioritizing simplicity and cost savings, rebuilding the existing gearbox is a viable option. Entrusting this task to a reputable specialist familiar with British transmissions is crucial. Ensure the rebuilder utilizes high-quality components and avoids simply replacing worn parts with marginally better used parts. Consult with suppliers like Denis Welch Motorsport or AH Spares to identify upgraded components suitable for your existing gearbox. This investment can significantly enhance the reliability and longevity of the original unit.
Conclusion
Choosing the right shift gearbox depends on individual priorities and resources. While a well-rebuilt original gearbox with upgraded components offers a reliable and cost-effective solution, converting to a center-shift setup provides a more modern driving experience. While more demanding, the Tremec and Smitty kits deliver a stronger, fully synchronized transmission. Careful consideration of budget, mechanical aptitude, and desired driving characteristics will guide you to the optimal solution for your classic British car.
