Put a 4L80E Transmission In Your 1969 GTO Judge

Posted by on Monday, December 1st, 2014

The 4L80E is a super heavy duty four-speed automatic overdrive transmission built by General Motors.   It is heavily based on the older Turbo Hydromatic 400 3 speed transmission.  The main difference is the number of gears, the gear ratio’s, and the fact that the 4L80E is fully electronic (the TH400 is not).  The electronics in the 4L80E include solenoids used in the valve body, a lock up torque converter and a number of sensors. The 4L80E incorporates a nice 2.48:1 first gear ratio and a generous 0.75:1 overdrive (25% overdrive) gear ratio. This transmission was first put into use in 1991 and stayed in production up through the end of the 2006 model year. The 4L80E transmission could be found in a wide range of both GM and non GM vehicles, including the Jaguar XJ12, the Aston Martin DB7, the Bentley Continental R, the Roll Royce Silver Spirit, the Hummer H1, the Chevrolet Avalanche and the GMC Sierra.

Install a modern 4L80E transmission into your earlier Pontiac GTO Jdge


The 4L80E makes for an excellent transplant candidate because of its heavy duty construction and 4th gear overdrive gear. One car that could benefit from this transplant is the 1969 Pontiac GTO Judge.  The GTO is built on the base model Tempest/LeMans. The GTO Judge was special high-performance version of the second generation GTO.  Much credit for the GTO’s being is given to the legendary John DeLorean (the same guy who later would introduce the DeLorean supercar).

Old muscle car are a great to own, but are hard to drive in modern traffic because of the lack of overdrive gear.  By adding a 4L80E to your GTO, you will get better mileage and be able to keep up with modern highway speed (due to the motor turning slower rpm’s). Here are some of the basics you will need to put the 4L80E into your GTO Judge.

  • A shorter drive shaft: The 4L80E is longer than the original transmissions that came in the GTO. A quick trip down to your local driveline shop will fix that problem. Speak to your local shop about how to correctly measure for a short drive shaft.
  • New transmission yoke: The 4L80E take a different transmission yoke than the original transmission. Here again, your local driveline shop should be able to supply you with the correct transmission yoke.
  • Standalone computer system and wire harness: Because the 4L80E is an electronic transmission, it will require a stand along computer to operate. Companies like Street and Performance offer wire harnesses that are designed to work with a donor OE computer. If you prefer something with a little more adjustment, consider a complete system from a company like TCI.
  • Cross member location: Luckily, this is an easy fix. Because the GTO has a full frame, all you need to do is slide the original cross member back on the frame until in lines up with the 4L80E’s transmission mount. You will need to drill 4 new holes in the frame to attach the cross member to its new location.
  • Shifter: Because the 4L80E is a four speed transmission, and the original transmissions found in the GTO were all three speeds, you will either need to modify the original shifter or install a new one.  Companies like Genie or B&M make standalone shifter that can be used.  Most of these aftermarket transmissions include micro switches for the reverse lights and neutral safety switch.

If you’re looking for a quality remanufactured transmission, then you won’t do better than ETE REMAN. That’s why we offer a three-year/unlimited mileage warranty on all our products. Browse our online catalog and contact us today.

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