4L70E Sprag Clutch 1997, used and ready to install. Fits the 4L70E. Ships fast from the USA.
A GM truck that revs in Drive and barely creeps, or moves fine in manual Low but not in Overdrive, often has a forward sprag that no longer locks. This is a complete used GM forward sprag assembly for 1997-and-later 4L60E, 4L65E and 4L70E transmissions, sold as a set with the input sun gear. Instead of just the sprag element, you get the forward sprag, its inner and outer races, the input sun gear, the overrun clutch hub and the snap ring, already matched to each other. Each assembly is cleaned and inspected before it ships.
The forward sprag is a one-way clutch inside the input housing. In first, second and third, the applied forward clutch turns the outer race, the sprag locks, and power goes through the inner race into the input sun gear, which drives the front planetary set. When the transmission upshifts to fourth or the driver lifts off the throttle, the sprag freewheels so the gears can overrun without a clutch fighting them. The overrun clutch, applied in manual ranges, bypasses the sprag to give engine braking. That bypass is the key to diagnosing it.
The 4L70E sits behind 5.3L and 6.0L V8s in trucks that tow, so every hard launch loads the sprag elements and races. Once the races pit or the elements wear, the sprag starts to roll over under load.
Road test in Overdrive and then in manual 3. If the slip or no-drive condition clears when the overrun clutch is applied, the sprag is not holding. If the truck will not move in any forward range, look at line pressure, the forward clutch and the pump before blaming the sprag. Our 4L70E delayed engagement guide covers those checks, and the 4L70E common problems guide lists the other failures that feel similar.
This assembly is listed for 1997-and-later 4L60E, 4L65E and 4L70E units, the later design of the forward sprag and input sun gear. That covers 2006-2013 Silverado, Sierra, Tahoe, Yukon and Trailblazer SS 4L70E units, as well as 1997-up 4L60E and 4L65E trucks and SUVs. Earlier 700R4 and 4L60E units used different input sun gears and sprag designs, so compare the old parts before installing. If you only need the sprag element and the low roller clutch, our 1986-2014 sprag set is the alternative. Send your year and VIN if anything is unclear, and browse the 4L70E parts page for the rest of the unit.
Before the input housing goes back in, hold the outer race and turn the input sun gear: it must lock one way and spin freely the other. A sprag installed backward gives no drive. Check the sun gear bushing and teeth, and replace the input housing seals while it is apart. Since a broken sprag sends metal everywhere, pair this with a 4L70E rebuild kit, inspect the sun shell for cracked splines, flush the cooler, and fill with Dexron VI.
| Fits | 4L70E 1997 |
| Part type | Sprag Clutch |
| Condition | Used |
| Brand | OEM |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
The forward sprag, its inner and outer races, the input sun gear, the overrun clutch hub and the snap ring, as one used GM assembly.
It is listed for 1997-and-later 4L60E, 4L65E and 4L70E units, which includes the 2006-2013 GM trucks and SUVs that use the 4L70E. Compare your old parts and send us your year and VIN if you are unsure.
That is the classic forward sprag pattern, because manual ranges apply the overrun clutch and bypass the sprag. Confirm line pressure and the forward clutch before tearing down.
The 1986-2014 set is a forward sprag element plus a low roller clutch. This assembly is the complete forward sprag with races, input sun gear and overrun hub for 1997-up units.
GM specifies Dexron VI automatic transmission fluid. Flush the cooler so debris from the old sprag does not come back.
