Thrust loads from output shaft and gear train coupled with poor quality replacement bearings.
Replace OE bearing with OE-quality Sonnax thrust bearing.
Sonnax fully enclosed selective thickness thrust bearing 77731-10 is a direct OE replacement for the rear planetary captive thrust bearing in GM 4L60 series units. Sonnax also offers 0.140” thick bearing 77731-09.
Planetary pinions must be removed for installation.
Contact a Sonnax Parts Distributor.