May 31, 2009

A New Trick in the Bag: Additional 2nd Gear Servo Size for the 4L60-E

Gregg Nader

For years we have known the 4L60 and 4L60-E 2nd Gear servo came in three different sizes, and one aftermarket size in the Sonnax 2nd Gear super hold servo kit 77911-03K. All of these servos have a “proper” apply to release ratio and accommodate a cushion spring. With the 2007 4L70-E, there is a fourth OE servo size that gives builders another choice when looking for something with increased performance.

The 8642553 casting used in V6 and V8 applications is by far the most common size we see. However, if you are looking to add "a little extra" to a heavy-duty rebuild and want a little more 2nd band apply area, but the Corvette or larger Sonnax super hold servo is just too much for a daily driver, try Sonnax 4L70-E servo 77701-02K. This mid-range servo size is a perfect first option to consider when upgrading stock-type applications.

The Sonnax 2nd Gear "Corvette" ratio servo kit 77701-04K is an upgrade from the smaller-ratio stock servo and adds holding power in many street applications. The exclusive Sonnax design features Viton® D-rings for more consistent apply and release than stock servos. The Sonnax super hold servo can be used as an upgrade from a stock "Corvette" servo or to add max holding power in extreme applications.

Compared to the "Corvette" servo, the 4L70-E servo is a modest increase in size over the V6/V8, 8642553 casting servo, and it will not change the shift feel as dramatically the Sonnax "Corvette" servo or a larger Sonnax 2nd Gear super hold servo would. Like the other Sonnax servos, the Sonnax 4L70-E servo features improved seals to enhance sealing during apply and release, making it so there are plenty of options to change shift feel and upgrade this common transmission. This 4L70-E servo is one more part you can add to your bag of tricks.

Click here to check out our comprehensive 4L60/E build guides.

The four OE 4L60 second gear servos are in the top row and divider rings are in the lower row. The ring represents the apply area on the second gear piston. The smaller the inner hole on the ring, the greater the second gear apply area.

Gregg Nader is a Sonnax Technical Specialist and a member of the Sonnax TASC Force® (Technical Automotive Specialties Committee), a group of recognized industry technical specialists, transmission rebuilders and Sonnax Industries Inc. technicians.

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