Keep the 4L80E Transmission in Your Shuttle Bus Running Like a Top

Posted by on Wednesday, July 30th, 2014

The 4L80E is a very heavy-duty, four-speed automatic overdrive transmission. It is heavily based on the earlier three speed TH400 transmission. The 4L80E is a fully electronic transmission that uses electrical solenoids to shift the transmission and incorporates an electronic look-up torque converter. It uses a 2.48:1 ratio first gear and a 0.75:1 ratio overdrive gear.

This particular automatic transmission first went into use back in 1991 and remained in the GM lineup through the end of the 2006 model year. It could be found in also sorts of heavy GM vehicles, including the Chevrolet C/K pickup, the Suburban, the GMC Yukon, the Avalanche, and the Hummer H1. It could also be found in the heavy-duty versions of the full-size Chevrolet Express vans that made up the chassis of many shuttle buses.


Chevy van-based shuttle buses come with the 4L80E transmission.

When a shuttle bus is built, it uses the cab, the chassis, and the running gear of the Express van. A new body in then married to the chassis, with some capable of seating for up to 16 people (possible by stretching the original van’s frame). These vehicles are extremely heavy and clumsy. Loaded with passengers and their luggage, they can easily weigh over 12,000 lbs. That’s a whole lot of weight for the poor 4L80E transmission to be hauling around. To make matters worse, these vans are constantly stopping (to unload/ load passengers) and run hours on end with no break. Since these vans must be running to make any money, it is crucial that all that can be done to protect your transmission is done, so your van remains reliable. Here are a couple tips to keep the 4L80E automatic transmission in your shuttle bus running like a top:

Without a doubt, the most important thing you must do is change the transmission fluid, and often. While GM may recommend that you go longer mileage intervals between transmission fluid changes, I recommend that you change the fluid every 20,000 miles or sooner. The constant stop-and-go nature of a shuttle bus dictates this as a necessity. When changing fluid, it is highly advised that you switch over to a good quality synthetic transmission fluid. Synthetic transmission fluids have much better wear protection properties and will help extend the life of the internal moving parts found in your 4L80E transmission. Synthetic fluids are also much better at handling the extreme ends of the transmission temperature range, and will not break down nearly as easily as their organic, oil-based cousins.

Excessive heat is going to be the number one issue from which you must protect your 4L80E. Excessive heat is responsible for the majority of 4L80E transmission failures. Ideally you want to keep your transmission under 200 degrees. This in an obtainable goal if you invest in and install a good quality transmission cooler. Because shuttle buses seldom see high speeds, I would look for a cooler that has its own built-in electric fan.

Sooner or later, due to high mileage or abuse, you will be faced with the decision to replace the 4L80 transmission in your shuttle bus. We highly recommend doing so with a re-manufactured transmission over one that was simply rebuilt. A re-manufactured transmission will include major internal modifications and upgrades designed to make it both stronger and more durable. To learn more, contact ETE Reman today!

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