For years, car enthusiasts have sought the perfect overdrive transmission swap for their vintage muscle cars. While TREMEC five- and six-speed transmissions have been popular choices, many require extensive modifications to fit older cars. This article focuses on installing a TREMEC TKX five-speed transmission into a 1969 Chevrolet Chevelle, minimizing floor pan modifications while improving drivability and performance.
TREMEC TKX – The Perfect Solution for Classic Cars
The TREMEC TKX is specifically designed for retrofit applications. Unlike bulkier alternatives like the T-56 or TKO series, the TKX has a slimmer profile, allowing it to fit into most classic muscle cars without significant tunnel modifications.
- Dimensions: Less than 31 inches long and 10.5 inches wide.
- Torque Capacity: Rated at 600 lb-ft.
- Overdrive Ratio: Up to 0.68:1, improving fuel efficiency.
- Compatibility: Designed for GM and Ford applications, with specific case patterns and transmission mounts.
- High RPM Handling: Supports rev ranges up to 7,500 rpm, making it ideal for LS and LT engines.
Pre-Installation Preparations
Before installing the TKX, several modifications must be made, especially when converting from an automatic to a manual transmission:
1. Pedal Assembly
The stock brake pedal is replaced with a clutch/brake pedal assembly. Additionally, a hydraulic clutch system is installed to reduce pedal effort.
2. Flywheel and Clutch
Since the car previously had an automatic transmission, the original flexplate is removed and replaced with a flywheel. A McLeod RST twin-disc clutch is installed to match the TKX’s 26-spline input shaft.
Step-by-Step Installation of the TKX
1. Measuring and Checking Alignment
Before installing the transmission, the bellhousing’s runout is measured with a dial indicator to ensure proper alignment. Misalignment can lead to premature wear and poor shift quality.
2. Cutting the Shifter Hole
Since this Chevelle originally had an automatic transmission, a new hole must be cut in the floor for the manual shifter. A factory-style reproduction transmission hump is used to maintain an OEM look.
3. Installing the Transmission
The TKX is carefully lifted into position. A small amount of grease is applied to the input shaft for smooth engagement. The transmission is bolted in place, ensuring the throw-out bearing is properly aligned.
Road Test and Performance Improvements
After installation, a test drive is necessary to evaluate performance. The TKX significantly reduces cruising RPMs, leading to better fuel efficiency and smoother highway driving.
Cost Analysis of the Swap
The entire swap, including the TKX transmission, clutch, flywheel, and other components, typically costs under $4,500. This makes it a cost-effective way to enhance a classic car’s drivability.
Conclusion
The TREMEC TKX is an excellent solution for vintage GM A-Body owners looking to upgrade to a five-speed manual transmission. Unlike bulkier alternatives, the TKX offers a near drop-in fitment, requiring only minor modifications.
With complete swap kits available for under $4,500, including the transmission, bellhousing, clutch, and pedals, this conversion is a cost-effective way to modernize a classic muscle car while retaining its vintage charm.
