4L80E Swap

How do I do a proper 4L80E swap and what will it cost me?

This is perhaps the most common question we are asked. To save everyone time and to have a handy reference point for those who are planning ahead, we decided to compile this guide together to give you a thorough look at what you will be facing in terms of parts and costs to do a proper, full 4L80E swap in your vehicle. The 4L80E is becoming an increasingly popular choice among enthusiasts today. The car scene is not how it was 10 years ago, the aftermarket has exploded even further, and nowadays 800hp is the new 500hp. Bone stock factory transmissions simply aren’t up to the task, and even a factory 4L80E, while notably durable in stock form, is not capable of reliably holding big power for the long term. You may hear of success stories, but they are the exception and not the rule. If a junkyard pullout 4L80E was capable of holding 700rwhp+ for years on end, everyone would be doing it, and we and other builders would not be here today.

The 4L80E swap is common in trucks and old school muscle cars, but the 4th generation F-body crowd is perhaps the most prolific case today, so this guide is more geared towards them, though the principles remain the same for almost every vehicle. Certain examples for vehicles such as trucks or older cars that did not come equipped with a factory PCM will be covered further down the list, so don’t feel left out! If you will look below you will notice a checklist of parts needed to swap a 4L80E into a 4th gen F-body. We will be covering everything in a fair amount of depth, and if you have any further questions, please email us and we may amend the guide if there is anything we have left out.

Parts Checklist

  • 4L80E
  • Converter
  • 4L80E Crossmember
  • 4L80E Trans Mount
  • Flexplate (SFI recommended)
  • 1350 Yoke & U-Joints
  • Transmission Cooler
  • Cooler Lines and Fittings
  • Method of Control


This section is going to give you an overview of the parts and why you need them. The average or estimated cost for the parts and procedures listed below are shown. Assuming you’ve already viewed the checklist above, let’s get started.

Transmission and Converter – Varies

Obviously a transmission and converter is needed for the swap, so we’re going to assume you already have that.

Crossmember – $150 – $200

A new crossmember is more than likely in order. Some T-56 users have been able to modify their existing crossmember to work with the swap, but we do not do that ourselves, though we can see the merit in saving a few dollars to do it yourself that way if you already have the crossmember. There are two crossmember options for a 4L80E swap in a 4th gen, with torque arm mount and without torque arm mount. The majority of you are going to want the crossmember WITH the torque arm mount. BMR makes a solid, affordable crossmember for the 4L80E swap and that is what we recommend, although anyone who is experienced enough with fabrication can probably figure out how to make one on their own if they would rather go that route. The BMR is an easy and quick bolt in solution. For those of you running a tunnel mounted torque arm, a crossmember with no torque arm mount will be perfect, and you can source these from companies such as BMR or Midwest Chassis.

4L80E Trans Mount (Rubber) – $15

This one is largely self explanatory. Purchase a transmission mount of your choice and bolt it to your tailhousing to link up to the crossmember.

Flexplate – $270

A new flex plate is not automatically a necessity, but we recommend it. If you are swapping from a T-56 to a 4L80E, a new flexplate is in order regardless, but if you are swapping from a 4L60E, you can retain your original flexplate and have the converter custom made to bolt up just like a 4L60E converter would. However, we don’t recommend this. We would recommend a flexplate that is SFI rated, such as the TCI option, or any other company of your choosing. Our way of thinking is, if you’re going to spend the money on an entire 4L80E swap, it would behoove you to spend a little extra on a nice, new SFI rated flexplate that you know will not crack. Stock plates are not an ideal solution for high horesepower units, and we have all witnessed more than a few examples of a faulty flexplate taking out a motor and transmission simultaneously. Then the car is down, the drive train is toast, money is being wasted, everybody is unhappy, it just plain sucks.

1350 Yoke – $80

This is a simple part of the swap. Your stock yoke is not compatible with the 4L80E output shaft splines, so a 1350 yoke is in order. Spicer or Strange will both work, it’s up to each person’s preference. New U-joint and U-joint braces are recommended. As for your driveshaft, assuming you are ordering you 4L80E through North Texas Converter, no modification is needed to the length. We machine a portion of the output shaft for increased slip yoke spline engagement which enables the stock aluminum driveshaft to retain it’s stock length.

Transmission Cooler – Varies by size

Rule of thumb, the bigger the better. If possible, we like to mount the cooler to the front of the radiator. If you are stuck on a brand such as B&M, that is perfectly fine, but we prefer to use Tru-Cool coolers, as they are manufactured in the same facility as the B&Ms and are functionally identical, but at a lower price.

Cooler Lines and Fittings – $120

Quite simple really. If possible, we recommended braided lines. Yes, they can be a bit of a pain to work with sometimes, but they are very sturdy and sure do look nice! Fittings vary from setup to setup, there are no particular predefined fittings to use, but choosing the right ones is fairly easy.

Method of Control – Varies by method. $30 – $500

Alright, at this point you have everything you need in terms of parts for the swap, everything is together and ready to go, all that’s left is figuring out a way to control the transmission. With a 4L80E you can either control it in a fully automatic fashion (our preference) or a full manual forward shifting pattern. There are no reliable, practical reverse manual valve body options for the 4L80E at this time, and the demand is fairly low, so R&D into such a modification is rather limited across the industry. We at North Texas Converter do not bother with full manual valve bodies for the 4L80E. We find them a tab cumbersome and often flawed, so instead we opt for the electrical solution. We offer a plug and play full manual control box that allows you to plug into the external connector of the transmission on one end, and splice 2 (3 on T-brake models) wires for full manual control. One wire is for power, and one is for a TCC toggle switch. Simple as that. It’s the cheaper alternative to the fully automatic control, but if you are seeking a car that has a stock feel to it, or want the inexperienced S/O to drive the car from time to time, we recommend the automatic solution.

To automatically control the 4L80E in a 4th gen F-body, you have several options.

Segment Swap: Using a tuning program such as HPTuners, users can swap a 4L80E segment from a .BIN file from a 4L80E equipped vehicle. This is one of the more popular routes to go, but will not work on ’98 F-Body PCMs.

Speartech Harness: The Speartech Harness is another simple alternative for full automatic control. Plugs into the new transmission and the other end is fully terminated and labeled for easy hook-up to your ECM connectors. ECM reprogramming required for proper operation. Options available for both factory equipped 4L60E and T-56 owners.

Relay Mod: Developed by NTC co-owner JT, this mod utilizing a simple relay and some basic wiring allows ’98 PCM owners to have fully automatic control without having to use a standalone controller. This mod also allows LT1 4L60E equipped vehicles and 2004 Pontiac GTO’s to control the 4L80E while retaining the stock PCM, among others. This mod is especially nice due to the fact that it allows factory 4L60E equipped PCM’s to control a 4L80E without the use of an aftermarket harness nor a segment swap, making it a simple and very cost effective option.

US Shift Standalone Controller: Especially used in older vehicles without the electronic capabilities the more modern cars offer, the Baumann Electronics US Shift (Formerly OptiShift) is arguably the best transmission controller on the market, and as the most expensive control option, it has the price to back it up. Its features are far too many to list in a simple description, but it allows maximum control and tuning capabilities of the transmission via onboard control or the USB to laptop interface. It also acts as a standalone controller, making it the ideal choice for older muscle car owners seeking a more modern drivetrain. Discounts available on the controller in conjuction with a transmission purchase.

SFI Flexplate
1350 Yoke
4L80E Crossmember