Factory GM 24229604 reaction sun gear shell for the 4L60E, 4L65E and 4L70E, the part to replace when a stripped shell spline takes out reverse and drive.
The classic 4L60E teardown story goes like this: the truck pulls away in first, revs up through the 1-2 shift as if it dropped into neutral, picks up again in third, then has no reverse at all. That pattern points straight at the reaction sun gear shell, and this listing is the factory replacement for it: GM part number 24229604, supplied through ACDelco, painted, made in the United States and listed by GM for the 4L60E, 4L65E and 4L70E. It is for the rebuilder or owner who wants the original-specification shell back in the case.
The 4L60E gets its four forward ratios and reverse from two planetary gearsets. The reaction sun shell is the steel drum that links the reverse input housing on the outside to the reaction sun gear in the middle, through a short splined hub. In second and fourth the 2-4 band clamps the reverse input housing, and the shell holds the reaction sun gear stationary through those splines. In reverse the reverse input clutch drives the same housing, and the shell turns the sun gear. First and third do not depend on it, which is why a failed shell leaves the truck with first and third only. Because so much torque passes through a small hub, the splines can round off, or the hub can crack and separate from the drum, especially behind towing loads or added power. Sonnax also points out that the rear planetary bearing riding against the shell is a chronic failure point, so the shell and that bearing should be inspected together.
Check fluid level first and scan for codes. If the solenoids test good and the truck has first and third but not second, fourth or reverse, the shell is the leading suspect, though a burnt 2-4 band or a leaking servo can cause a similar no-second, no-fourth complaint. Reverse is the tie-breaker: the band does not work in reverse, so losing reverse as well points to the shell. Our 4L60E common problems guide covers the full sorting process, and the 2-4 band and servo guide explains how to rule out the band side. Final confirmation comes at teardown, when the hub splines are visibly stripped or the hub is loose in the shell.
GM lists 24229604 for the 4L60E, 4L65E and 4L70E. That covers the rear-wheel-drive 4L60E family used in Silverado and Sierra 1500, Tahoe, Yukon, Suburban, S10, Blazer, Camaro and Corvette applications, along with the heavier-duty 4L65E and 4L70E trucks and performance cars. GM made thrust-stack and bearing changes across the long production run, so compare the new shell to your old one, including the hub spline and the bearing or washer surface, and confirm fitment with your year and VIN before ordering. Every sun shell option we carry is in the 4L60E parts collection.
Lift out the reaction carrier and sun gear, then pull the old shell off the reverse input housing. Inspect the reaction sun gear splines closely; a worn gear will strip a new shell quickly. Check the drive tangs where the shell engages the reverse input housing, and replace the thrust washer or bearing that rides on the shell. A shell failure throws steel through the whole unit, so inspect the low roller clutch, the input sprag and the 3-4 clutch pack before assembly. The 4L60E input sprag and a heavy-duty 3-4 clutch pack kit with filter are common add-ons for this job. If the truck tows heavy or makes extra power, the Beast heavy-duty sun shell is the stronger aftermarket choice. Flush the cooler and lines, check end play, refill with Dexron VI and set the level hot.
| Part number | GM 24229604 (ACDelco) |
| Fits | GM 4L60E, 4L65E, 4L70E |
| Type | Reaction sun gear shell, OE replacement |
| Finish | Painted |
| Item weight | 2.98 lb |
| Country of origin | United States |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Typically reverse, second and fourth. The shell holds the reaction sun gear in second and fourth and drives it in reverse, so first and third usually still work.
Yes. 24229604 is the GM genuine part built to factory specification. If your truck tows or has added power, a heavy-duty aftermarket shell is worth considering instead.
GM lists 24229604 for the 4L60E, 4L65E and 4L70E. Confirm with your year and VIN, and compare the thrust surfaces to your old shell before assembly.
No. The shell sits in the middle of the gear train, so the transmission has to come out and be disassembled down to the planetary sets.
Replace the thrust washer or bearing on the shell, inspect the reaction sun gear, low roller clutch and input sprag, and flush the cooler. Metal from a failed shell travels through the whole unit, so most shops do a full overhaul at the same time.
