The Square Body Chevy is an iconic vehicle that blends vintage aesthetics with modern-day practicality. This classic truck has made a name for itself in the automotive world, being both collectible and functional. In episode 3 of the Square Body Rehab YouTube series, Hemmings takes their Square Body Chevy to the next level with upgrades aimed at producing some serious smokey burnouts. With the help of a lockup converter, overdrive transmission, and a limited-slip differential, the truck is transformed into a true burnout machine. If you’re looking to recreate this setup, you’ve come to the right place. This article will walk you through every step of the process, from the upgrades to the end result.
The Square Body Chevy
The Square Body Chevy, produced between the late 1970s and the 1980s, is one of the most beloved pickup trucks of all time. Known for its boxy shape and rugged build, this truck has gained a cult following over the years. Despite its age, the Square Body still holds up as a practical, reliable vehicle for day-to-day use, which is why it’s still popular among car enthusiasts today. While many classic vehicles are admired for their vintage appeal, the Square Body also brings a level of modern usability, making it ideal for restoration and performance modifications.
The beauty of working with a Square Body Chevy is that it’s old enough to be considered a classic but young enough to be a practical choice for modifications. Its durable frame and versatile design make it a perfect platform for customization. And when it comes to making it even more fun to drive, especially for those who love a good smoky burnout, the possibilities are endless. Episode 3 of the Square Body Rehab series shows how to enhance the truck’s performance to deliver that thrilling tire-scorching experience we all know and love.
Goals for Smokey Burnouts
The goal of this project is simple: to turn an already great truck into a burnout machine capable of producing thick, billowing clouds of smoke. Achieving this requires a combination of drivetrain modifications that can handle the power generated by the engine during a burnout while ensuring both rear wheels spin simultaneously. This is especially important because a one-wheel burnout isn’t nearly as dramatic or fun as a two-wheel burnout, where both tires lay down rubber in unison.
To make this happen, the Square Body Chevy needs to undergo a series of upgrades that address key areas of the drivetrain, including the transmission, torque converter, and differential. In particular, the project focuses on the installation of a lockup converter, the addition of an overdrive transmission, and the replacement of the factory peg-leg differential with a limited-slip unit. With these changes, the truck will be able to handle higher levels of power and torque, enabling it to execute burnouts that would make any enthusiast proud.
Building for Smokey Burnouts
To build a truck capable of impressive smokey burnouts, there are several key upgrades that need to be made. These modifications involve improving the way power is transferred from the engine to the wheels. The stock configuration of the Square Body Chevy, while reliable, isn’t optimized for the kind of performance necessary to achieve continuous, controlled burnouts. That’s why upgrading critical components is essential.
Lockup Converter and Overdrive Transmission
One of the most important upgrades for creating smokey burnouts is the installation of a lockup converter. The lockup converter ensures that the torque converter locks in place during high-speed driving or when performing a burnout. This prevents slippage and allows for direct power transfer to the wheels, improving acceleration and burnout performance. However, the Square Body Chevy’s stock setup doesn’t come with a lockup converter, so it’s necessary to retrofit the truck with a modern solution.
In addition to the lockup converter, an overdrive transmission upgrade helps enhance performance by offering better gear ratios. This means the truck will be able to maintain higher RPMs during a burnout, keeping the engine in its optimal power range. However, achieving this upgrade without modern ECU controls can be tricky, which is why a vacuum actuator system is used to manage the lockup converter in this particular build.
Vacuum Actuator Conversion
One of the challenges when upgrading to a modern overdrive transmission like the 700R4 is managing the lockup converter. The stock ECU (electronic control unit) of the Square Body Chevy is not designed to handle this kind of upgrade. To overcome this, Junior Nevison from Hemmings shows how to use a vacuum actuator to control the lockup converter.
The vacuum actuator works by using the engine’s vacuum pressure to control the engagement and disengagement of the lockup converter. This is an excellent solution for anyone who doesn’t want to deal with the complexity of reprogramming the factory ECU. By replacing the electronic control with a vacuum-actuated system, the lockup converter can function reliably, giving the truck the power it needs for those epic burnouts.
This approach simplifies the process, allowing DIY enthusiasts to perform this modification themselves at home. With a few tools and some patience, anyone can add this feature to their Square Body and start enjoying the performance benefits right away.
Differential Upgrade: Peg-leg to Limited Slip
Perhaps the most crucial modification for achieving smokey burnouts is upgrading the differential. The factory peg-leg differential found in many Square Body Chevys only sends power to one rear wheel, making it impossible to perform a proper burnout. In order to make both rear wheels spin simultaneously, the factory differential must be replaced with a limited-slip differential.
In this build, Junior replaces the peg-leg differential with an Eaton Truetrac limited-slip differential. The Truetrac is a performance-oriented unit that ensures power is distributed evenly between both rear wheels. This allows the truck to perform controlled burnouts, with both tires spinning at the same rate, creating the signature smoky effect that enthusiasts crave.
Upgrading to a limited-slip differential not only makes the truck better for burnouts, but it also improves handling on the road. The Truetrac differential ensures that both wheels rotate in unison, improving traction and providing a smoother driving experience. For anyone looking to increase the performance of their Square Body Chevy, this upgrade is a must.
Watch the Episode
To see how these upgrades come together and watch the Square Body Chevy in action, be sure to check out episode 3 of Square Body Rehab. Junior Nevison walks you through each step of the process, showing how to install the vacuum actuator, swap the differential, and achieve the perfect smokey burnout. The episode is full of tips and tricks for anyone looking to replicate these upgrades at home.
Conclusion
The Square Body Chevy is a versatile and reliable platform for performance upgrades. By adding a lockup converter, overdrive transmission, and limited-slip differential, you can transform your truck into a smokey burnout machine that’s sure to turn heads and leave tire marks wherever you go. Whether you’re an experienced mechanic or a DIY enthusiast, these upgrades are achievable with the right tools and some patience.
These modifications not only enhance the truck’s ability to perform burnouts but also improve overall driving performance. With a few key changes, you can unlock the full potential of your Square Body Chevy and experience the thrill of a perfectly executed burnout. So, what are you waiting for? Grab your tools and start building your own burnout beast today!
