Upgrading the A750E/A750F Transmission: 2nd Gen Tacoma RatioTek HD Kit Installation
Upgrading the A750E/A750F Transmission: 2nd Gen Tacoma RatioTek HD Kit Installation
Firming up your 5-speed automatic transmission reduces internal clutch wear and eliminates annoying torque converter shudder. Installing a heavy-duty shift kit is the ultimate mechanical fix for owners running forced induction or towing heavy loads.
The Short Answer (TL;DR)
Installing the RatioTek HD shift kit on a 2005-2015 Toyota Tacoma with the A750E or A750F 5-speed transmission takes about 4 to 6 hours. This advanced DIY modifies the factory valve body to increase clutch clamping force by 38% and eliminate excessive factory slip. Because you are draining the fluid, it is the perfect time to add a larger transmission cooler.
The DIY Process Overview
To install the RatioTek HD kit, you must drain the transmission fluid and drop the transmission pan to access the valve body. Carefully unbolt the valve body, noting the exact location of all bolts, as they vary in length. Once on the bench, you will disassemble the specified valve sections to install the upgraded springs and components. Reinstall the valve body, torque all bolts to factory specifications, and refill the system with fresh WS transmission fluid.
This is an advanced procedure that requires strict cleanliness and precision. A single misplaced check ball or incorrect torque spec can destroy the transmission or require a complete valve body replacement. Take your time, lay out your parts on a clean workspace, and double-check your assembly manual before bolting everything back into the truck.
Why You Should Upgrade While You're In There
Since you are already dropping the transmission pan and modifying the valve body to handle more power, your transmission is going to need optimal cooling. Increased line pressures and faster shifts generate heat, especially if you are running a supercharger, towing, or driving on oversized off-road tires. Upgrading your drivetrain cooling and software calibration ensures your newly built transmission operates efficiently.
Recommended Upgrade: Heavy-Duty Transmission Cooler and Engine/Transmission Tune. An aftermarket cooler drops operating temperatures significantly, prolonging fluid and clutch life. Pairing this mechanical valve body upgrade with a custom powertrain tune will correctly sync your shift points and lockup schedules, maximizing the benefits of the RatioTek kit.
Frequently Asked Questions
Is installing a valve body shift kit difficult?
Yes, this is an advanced DIY project. It requires removing the delicate valve body from the transmission, disassembling precision hydraulic components, and reinstalling everything with exact torque specifications. If you are not comfortable working with intricate internal transmission parts, you should leave this job to a certified professional.
What are the performance benefits of the RatioTek HD kit?
Toyota engineers these transmissions with a luxury shift calibration, which forces the clutches to slip longer for smoother gear changes. The RatioTek kit increases line pressure and clutch clamping force by roughly 38%, which stops torque converter shudder and reduces shift time. This firmer shift prevents premature clutch wear and effectively transfers power to the ground, making it mandatory for supercharged or heavily loaded trucks.
