Convert Your 4L60E To 4L65E Specs

The 4L60E transmission is... 

   

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The 4L60E transmission is a worthy unit, capable of withstanding the tortures of street/strip abuse as long as it has been outfitted with a few high-performance goodies

'The 700-R4 has long been a mainstay in the General's arsenal of late-model automatic overdrive transmissions. In 1993, OBD-II brought electronic controls and the introduction of the 4L60E. At the same time the 700-R4 was renamed the 4L60. Although the two transmissions have a similar name and share cases and some parts, they are different. In 2001, the 4L60E became the 4L65E when GM upgraded some key internal parts that were failing behind the increasingly powerful Gen III powerplant. The improved transmission utilized a stronger five-pinion rear planetary and a hardened input shaft and sun shell that increased its torque capacity to 380 lb-ft. The nice thing about all of this is that the modern parts are easily swapped into the 4L60E, leaving you with the ability to upgrade your existing tranny without having to buy a new unit.

Transmission rebuilding requires... 

   

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Transmission rebuilding requires specialized tools that are not found in your average toolbox. Shown here are just a few of those needed to work on the 4L60E. From top, left to right: Cotter key pick, Teflon shaft installer, rear clutch spring compressor, universal pump remover, electrical connection removal tool (a large socket will work but usually breaks a tab) and two snap-ring pliers. Not pictured are the front pump alignment band and turbine shaft installer. This might be an expensive do-it-yourself project.

Since the upgrade requires a complete teardown, a full rebuild with some extra performance pieces is a good idea. We used a Trans-Go reprogramming kit, a Sonnax billet Fourth gear Super Hold servo, a Raybestos Z-Pack clutch kit, and Red Eagle red oxide clutches. We cherry-picked the clutch kit, using the Z-pack for the 3-4 clutches. These are specifically designed to not bow and to have superior holding power. The red oxide clutches have better hold for 1-2.

This is not the most difficult tranny to build, but it is certainly not the easiest. And there are a few specialized tools needed to correctly complete the job. To get an expert's assistance we went to Tony Straughn of Budget Transmission in Stillwater, Oklahoma. The total package including labor priced out at about $1,300, not including the torque converter. We used an ATI High-Stall Street Master lockup converter, which had a pretty hefty price tag of $640.

The five-pinion planetary... 

   

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The five-pinion planetary carrier (right) increases the transmission's rated capacity to 380 lb-ft. That is a substantial improvement over the four-pinion carrier (left).

Upgrading to the 4L65E is advisable in towing applications and where horsepower numbers are up to 500. The 4L60E also uses a four-pinion front planetary carrier, which is more expensive than the rear unit. For cars making over that number, there is a front planetary upgrade as well. Our '96 Impala makes just under 500, so we upgraded the rear planetary only. After the upgrade, the car has a nice, snappy shift under part-throttle, and the full-throttle shifts are supersharp, much better than the stock slush box and more reliable, too.

If you want to find a 4L60E...        read full caption If you want to find a 4L60E in the wrecking yard and upgrade it to 4L65E specs, find one that was built after 1995, when GM converted the 4L60E converter lockup circuit to a pulse-width-modulated circuit. This type of lockup circuit offers a smoother transition, as it pulses the signal instead of jolting the driver with a sudden converter lock. These transmissions will be marked with "PWM" on the front of the pump. The important thing to remember here is that whatever the type, PWM or non-PWM, it must match the computer in the car; otherwise it will not function properly.

The pump pressure relief is...        read full caption The pump pressure relief is the number one cause of failure after overhaul. It is very easy to forget to clean this little ball and spring, and it tends to get gummy and start to stick. Even going a few miles down the road can cause a failure, because the converter can't release its pressure, leading to overheating.

The stock sun shell (left)...        read full caption The stock sun shell (left) has a tendency to crack and then shear off the gear at the neck in high-performance applications. The Beast sun gear (right) is made of thicker material and is particularly beefy where the problems occur. The Beast also comes with a new Torrington thrust bearing.