Upgrading GM 4L70E Transmissions Via Gearstar

Oct 4, 2016, 12:00 am
Upgrading GM 4L70E Transmissions Via Gearstar

Gearstar performance transmissions are all custom. Building each transmission with to the specific needs of the customer is important to Gearstar. We’re looking to maintain a standard of excellence in the industry.

The 4L70E is essentially the Late model of the 4L60E. It’s compatible with LS style engines rated up to 500 horsepower and is an extremely popular option for drag racers and performance enthusiasts. The 4L70E is a tough transmission that can be easily upgraded, which is part of its appeal. In fact, the 70E is considered the strongest trans in GM’s four-speed automatic overdrive transmission family, having the capability to handle more power than the 4L60E and 4L65E.

Let’s learn more about how the 4L70E came to be and why this transmission might be a great addition to your vehicle.

4L70E Launched in Late 90s

In 1996, GM introduced the two-piece 4L60E that featured a removable bellhouse. This allowed the transmission to be used in a wide range of GM engines, including the new V-8s from the LS series. Since its birth, the 4L60E has been an extremely solid and stable automatic overdrive transmission, with improvements focused on greater torque capacity, improved load capacity and better all-around performance.

With these improvements, the 4L65E was introduced, and then the 4L70E followed. What separates the 70E from its siblings are minor improvements, such as an additional clutch to the overdrive unit, hydraulic changes and a better planetary unit. Plus, the 4L70E is only fitted for the GM rear-wheel-drive half-ton Chevy and GMC trucks and SUVs. It can fit into small block, big block or LS engines with a few adjustments, which is why the transmission remains popular for muscle cars.

When to Make the Switch to the 4L70E

If you appreciate the small improvements in the 4L70E and want to upgrade from the 60E or 65E, making the swap is worth it. However, it’s nearly impossible to tell the difference between the transmission just by looking at them. Even the outside of the 4L70E is stamped with the 4L60E. Usually, people go to the 4L70E automatic trans when they need increased performance in terms of power and torque.

Gearstar is a trusted source for high performance transmission. We like to say that we build our transmissions with love, as this is exactly how we feel. We take exceptional pride in our quality parts and attention to the smallest details. Each transmission is custom built by the same technician, and there are options to upgrade the 4L70E for even better performance. For example, we can upgrade the friction materials to improve power rating and durability. And, if you decide that you need more power, we can talk about upgrading you to the 4L80, which is a great trans for ¾ ton and 1 ton trucks.

Upgrading GM 4L70E Transmissions Via Gearstar is promising. Rated for up to 650 hp and 650 lb-ft of torque makes the Gearstar 4L70E transmission a perfect upgrade solution. Read full specs for the Gearstar 4L70E Level Two Here.

During our chat with Mark Walk of Gearstar Performance Transmissions in Akron, Ohio, we learned a lot about these time-proven GM overdrive automatics. These are well engineered transmissions from the factory, however Gearstar knows how to make them better. “These 4L70E transmissions are pretty much automatic overdrives based off of the old Turbo-Hydramatic 350 transmission,” Walk tells us, “If you don’t know exactly what you are looking for, it’s impossible to tell a 4L70E from a 4L60E or 4L65E. There aren’t any physical differences externally in the case, furthermore, even the cases are still stamped 4L60E.”

The Gearstar 4L70E

First, each Gearstar 4L70E is custom built to order and engineered to perform. Raybestos Gen II clutches provide transmission blueprinting. Also heavy-duty steels and TransGo shift improvement kit. Finally, new high-performance hard parts throughout.
“When exceeding the factory ratings of around 450 horsepower and up, you’re going to need some improved performance components in the 4L70E transmission. Those improvement are determined by power, torque, and in addition what you’ll be using the car for. The 4L65E Level II, is our entry level high-performance transmission and it starts at 450 horsepower and 425 pound feet of torque. Consequently, at that point is when you need to start entertaining something that can handle more power.”

The 4L70E is a vastly improved version of the 4L60E. However, Walk tells us there’s room for improvement so your 4L70E will last under demanding conditions. While most people want a smooth shift, smooth shifts happen due to slippage, as a result, slippage creates heat. Heat sheds clutch/band friction material in the fluid, which damages seals. You want a firm upshift while having a smooth, unnoticeable downshift. Additionally, upgrading the friction materials in a 4L70E can go a long way in improving it’s durability and power rating. Moreover, GM’s E model automatic overdrives are more versatile and intelligent transmissions. The driver can have direct control of shift timing, wide open throttle up shifts, torque converter lock up apply, and at what MPH this takes place.


The GM 4L70E transmission is a stout and healthy unit in stock form. We’ve shown you how it is a big improvement from the more common 4L60E and 4L65E. A few improvements in hard parts friction materials and the 4L70E can easily stand it’s ground. Managing the type of power that today’s engines are capable of producing while maintaining the benefits of overdrive and electronic shift control.