Both one-way clutches a 4L60E rebuild needs: the heavy-duty 29-element forward sprag (29236AM) and the wide low/reverse roller clutch (28571AM), Borg Warner.
A Silverado, Tahoe, Camaro or S10 that revs and will not move in Drive, slips off the line, or flares on the 2-3 shift often has a one-way clutch that has stopped holding. The 4L60E family uses two of them, and this Borg Warner set replaces both in one order: the 29236AM forward sprag that goes in the input drum, and the 28571AM wide low roller clutch that goes in the center support. It fits the GM 700R4, 4L60E, 4L65E and 4L70E from 1986 through 2014 and ships from the USA.
The forward sprag sits in the front of the gear train. The forward clutch drives its outer race, and in Drive it locks to carry engine torque into the input sun gear through first, second and third. When the transmission shifts into fourth or you lift off the throttle, it freewheels so nothing binds. In D and 3 range the overrun clutch applies alongside it, which is how the factory gets engine braking and why a failed sprag can hide in those ranges.
The low roller clutch is at the opposite end of the case. The center support is its outer housing, snap-ringed into the case, and it holds the rear carrier in first gear in Drive with no oil pressure involved. In manual Low and Reverse the low/reverse clutch pack holds that same carrier instead. Because they are two different designs, they fail differently: sprags tend to let go suddenly, while a roller clutch usually wears its cage and springs and gets worse over weeks.
The 29236AM is a 29-element dual-cage sprag. More elements than the earlier 27-element style spread launch torque across more contact points, which helps it resist rolling over under load. The 28571AM is the wide-style low roller clutch used in these units.
You can isolate each one-way clutch from the driver seat. Transmission Digest describes applying a clutch that holds the same member: if the vehicle moves in manual Low but not in the other forward ranges, the low roller clutch is not holding, and if a launch shudder is gone in D or 3 but present in Overdrive, the input one-way clutch is the problem. Our guide to 4L60E sprag and roller clutch failures lays out the full test, and forward clutch and sprag wear covers when the forward clutch itself is the cause. Burnt fluid and a slip in third and fourth point elsewhere, usually the 3-4 pack.
This set is listed for GM 700R4, 4L60E, 4L65E and 4L70E transmissions from 1986 through 2014, and it interchanges with GM part numbers 24217231 and 8654441 and cross-references A74654A and A74658C. This family stayed in production for nearly three decades with running changes along the way, so lay your old sprag and roller clutch next to the new ones and compare width and element count before you install them. If anything does not match, send us your year and VIN. Our 4L60E collection has the single-piece versions, including the GM 24217231 low roller clutch if you only need the rear unit.
| Fits | GM 700R4, 4L60E, 4L65E, 4L70E, 1986-2014 |
| Includes | Forward sprag (29236AM, 29-element dual cage) and low/reverse roller clutch (28571AM, wide) |
| Brand | Borg Warner |
| Interchange | 29236AM, 28571AM, A74654A, A74658C |
| OEM part numbers | GM 24217231, 8654441 |
| Ships | From the USA |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
It is listed for the GM 700R4, 4L60E, 4L65E and 4L70E from 1986 through 2014. Compare the new parts with your old ones before installing, or send us your year and VIN to confirm.
Both are buried in the gear train, so getting back to either one means a full teardown. If the unit is already apart for a rebuild, replacing both removes a common cause of a comeback.
If the vehicle will not move in Drive but moves in manual Low, the low roller clutch is not holding. If a launch shudder or 2-3 flare goes away in D or 3 but is present in Overdrive, the forward sprag is the suspect.
The extra elements over the earlier 27-element design spread the load, so the sprag holds more torque before elements roll over. It suits stock units and mild power increases.
Dexron VI ATF. Flush the cooler and lines first if the old sprag broke up and left debris in the pan.
