6L90 Sprag Clutch, new and ready to install. Fits the 6L90. Ships fast from the USA.
A 6L90 that pulls away like it is in neutral, then catches once the truck is rolling, or one that has no first gear in Drive but moves in other gears, very often has a low sprag that has quit holding. This is a new genuine GM low clutch sprag kit, reference 24248958, for the 6L90 in the 6.0L Chevrolet Silverado 2500/3500 and GMC Sierra HD, the Express and Savana vans, and the other heavy-duty applications of this six-speed. The kit shown includes the sprag assembly and the O-ring seal pictured with it.
The low sprag is a one-way clutch. In first gear it locks the output carrier against rotation so engine torque turns the wheels, and it freewheels the moment the transmission shifts to second so the 1-2 shift needs no clutch-to-clutch timing. On the 6L80 and 6L90 the low/reverse clutch also applies at launch to help it, then releases at roughly 2 mph and leaves the sprag carrying first gear on its own. That design means a weak sprag can look fine at a dead stop with the brake on and still let go just as the truck starts to move. In manual low and in reverse the low/reverse clutch does the holding, which is why a bad sprag often leaves those ranges working.
Technicians writing in GEARS magazine point out that a slipping low sprag is easy to misdiagnose as a 1-2-3-4 clutch failure, because both give you a launch with no drive. The quick separation: the 1-2-3-4 clutch is applied in first through fourth, so a burned one usually slips in all four gears, while a failed sprag affects first gear in Drive only. Compare first in Drive against manual low; if manual low pulls and Drive does not, the sprag is the prime suspect. Check fluid level hot and read codes first, and rule out a worn checkball #1 feed circuit as described in our 6L90 common problems and fixes guide. If the unit comes apart, inspect the sprag elements and both races closely; a polished or pitted race is just as much a failure as a broken element.
GM catalogs 24248958 as the low clutch sprag kit for 2007-2023 rear-wheel-drive six-speed applications, including the 6.0L and 6.6L gas Silverado and Sierra 2500/3500 and the Express and Savana vans, and it has since been superseded by 24050202. It is listed here for the 6L90. Sonnax builds separate low/reverse sprag rebuild kits for the 6L80 and the 6L90, so do not assume a sprag from a lighter 6L unit interchanges; compare your old part or send us your year and VIN. For used 2006 and 2007 versions see the 6L90 sprag clutch 2007, and browse everything for this unit on the 6L90 parts page.
| Fits | 6L90 |
| Part type | Sprag Clutch |
| Condition | New |
| Brand | GM |
| Reference | 24248958 |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
GM's parts catalog shows 24248958 superseded by 24050202, and 24248958 itself replaced the earlier 24238334. This listing is the 24248958 sprag kit.
In manual low the low/reverse clutch holds the carrier, so the sprag is not needed. In Drive the sprag carries first gear once the truck is rolling, so a sprag that will not lock gives you no first gear in Drive only.
It may set a gear ratio or slip code on some trucks, but often there is no code at all. Diagnose it by comparing first gear in Drive against manual low rather than relying on codes.
The low/reverse clutch frictions and steels, the seals in a master rebuild kit, and the inner or outer race if either shows pitting. Check the 1-2-3-4 clutch while the unit is apart.
Do not assume it does. Sonnax sells different sprag rebuild kits for the 6L80 and 6L90. Match your existing part or send us your year and VIN before ordering.
