Throwback Thursday: LS-Swap Automatic Transmission Guide

Here we are once again, the week is nearing completion. That means Thursday has landed on our doorsteps. With the end of the week nearing, are you making weekend garage plans or have they already been made. If your plans for enjoying some garage time with your project include finishing that LS swap, you might ant to check this out.

In this edition of Throwback Thursday, we’re taking a leap back to February 2016, to check out: LS-Swap Automatic Transmission Guide. That article was put together to give our readers a deep dive into understanding their automatic transmission options when doing an LS swap.

LS transmission

The three-speed Turbo 350 (left) and four-speed 4L60E are dimensionally similar and share a common ‘family tree.’ Most vehicles that were factory-equipped with the Turbo 350 won’t need any substantial modification to accept the overdrive 4L60E.

To get some expert advice on the topic, we reached out to a professional in OE world, and another in the  aftermarket. Rusty Sampsel from Chevrolet Performance and Kevin Winstead from TCI were more than qualified to field our questions.

“The Turbo 350, Turbo 400, and Powerglide are a direct bolt-on for an LS engine,” explains TCI’s Winstead. “The block’s dowel pins are in the correct location, and five of the six bellhousing bolts align. However, the torque converter bolt-pattern and pilot length is different on the LS transmission applications.” Fortunately, the solution to this problem is a simple one. Per Winstead, “You can have a converter custom-built for the application, or you can change the flexplate to one that has the correct bolt pattern and accommodates the different pilot length of the older type torque converter.”

LS transmission

Choosing the transmission that is right for your particular LS swap will involve not just the big items like the gearbox itself, the crossmember, driveshaft, converter, and flexplate, but supporting components such as the shifter and control electronics. Both TCI and Chevrolet Performance offer packages to make easy swaps into just about any chassis.

In the original article, Rusty Sampsel made this point, “the 4L60/65/70 are basically a Turbo 350 with the overdrive added. The 4L80/85 are a Turbo 400 with the overdrive added,” he explained. “The overdrive transmissions are slightly heavier and larger than the non-overdrive Turbo 350 and Turbo 400 units. If an older vehicle came with a Turbo 350, most times, a 4L60/65/70 will likely fit without too much effort. The same can be said for Turbo 400 and 4L80/85. If you are wanting to go from a car that originally came with a Turbo 350 and replace it with a 4L80/85, you might have to make some floor/crossmember modifications.”

The original article gets granular with many of the details you need to consider when doing a swap like this. I know there are a multitude of power junkies reading this, and that is why I thought: LS-Swap Automatic Transmission Guide was the perfect article for this week’s Throwback Thursday.

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About the author

Randy Bolig

Randy Bolig has been working on cars and has been involved in the hobby ever since he bought his first car when he was only 14 years old. His passion for performance got him noticed by many locals, and he began helping them modify their vehicles.
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