March 07, 2019

Tech Tip: How to Install Sonnax 4L60-Series Wide Reaction Sun Gear Bushing

This information can also be found on the part page and instructions. We strongly advise that you read the instructions for all Sonnax parts before installation to ensure it is done correctly. All instructions are easily accessible on the Sonnax website. Use the handy instruction finder at

The Sonnax wide reaction sun gear bushing 77010-01 for GM 4L60, 4L60-E, 4L65-E and 4L70-E applications is one-and-a-half times the width of the OE version, and fills the entire sun gear bushing groove. This wider bushing maximizes support, and it’s steel-backed bronze that is precision machined to provide minimal clearance with the mating shaft.

Be aware that this bushing may not work in some late-production sun gears with OE finish-in-place bushings, so be sure to measure the sun gear bore. Installing this bushing into a bore that is smaller than 1.705”-1.706” will result in a tight fit with the mating reaction shaft.

1. Install the bushing using an arbor press.
2. Press the bushing in until it's lightly seated against the ridge in the bore (Figure 1). Check the bushing alignment with the small lube hole on the mating reaction shaft to make sure the bushing does not block the lube hole.


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