Borg Warner 4L60E Forward + Low Reverse Sprag Set, 29236AM 28571AM

When a 700R4, 4L60E, 4L65E, or 4L70E loses forward drive, slips on the 1-2, or ratchets in reverse, a failed sprag is usually the reason. This set replaces both of the one-way clutches that fail in these units: the forward sprag that locks the input to drive the vehicle, and the low/reverse roller clutch that holds the sun gear for reverse and manual low. Doing both at rebuild is the right call, because pulling the case back apart to change the one you skipped is not worth the saved parts cost.

The forward piece is the Borg Warner 29236AM, the heavy-duty 29-element dual-cage sprag. The extra elements over the earlier 27-element design spread the load and let it hold more torque without the sprag rolling over and stripping, which is the common failure on stock and mildly built units. The low/reverse piece is the Borg Warner 28571AM wide roller clutch, the correct wide-style unit for these transmissions. Both are genuine Borg Warner, not offshore copies.

Fitment covers GM 700R4, 4L60E, 4L65E, and 4L70E from 1986 through 2014. It interchanges with GM part numbers 24217231 and 8654441, and cross-references A74654A and A74658C. On install, seat the forward sprag with the elements ratcheting the correct direction (it should lock holding the input drum and freewheel the other way) before you close the drum up, and check the low/reverse roller clutch rotation the same way against the sun shell. Ships from the USA.