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GM Transmissions

The 4L65E transmission, among others, was designed to replace the TH350. It’s a solid transmission that is similar to the 4L60E but with far more strength. The 4L65E was designed to handle more torque but has an identical looking case to its predecessor. However, the transmission is not compatible with the 4L60E because it uses a different torque converter and input shaft. If you plan on upgrading to the 4L65E, you will need a converter.

How the 4L65E Trans Has Evolved

The 4L65E was born because structural improvements needed to be made off older transmissions such as the 4L60E. The 4L65E is stronger, has better performance, a hardened sun shell and input shaft and a five-pinion rear planetary. Hot rodders appreciate having more pinion gears because the load is spread out and the transmission can handle more torque. Additionally, the 4L65E features a deeper pan for more fluid and a 3-4 clutch.

If you are in the market for a new transmission, you’re definitely doing yourself a favor by going with the 4L65E. Keep in mind that the older 60E is not compatible with the 65E, so you will need a converter. With the custom built transmissions from Gearstar, this is an easy issue to work around.

The only complaint that some drivers have had about the 4L65E is the jump from first to second gear. Some feel that the leap is too big. Yet for every person who doesn’t like the big jump, others love it. It’s all about preference, we suppose. There are some mods available to help with this wide ratio, but in actuality, there’s not much that can be done.

Custom Built 4L65E Transmission

The areas where four-speed automatics shine is their strength, abundance and opportunities for upgrade. Whether you’re interested in upgrading your current 4L60E transmission or are starting from scratch, Gearstar is happy to help! We custom build high performance transmissions using American-made parts. When you place your order, only one highly qualified technician will work on your transmission, ensuring that everything is given the appropriate attention.