200-4R Sun Shell, used and ready to install. Fits the 200-4R. Ships fast from the USA.
Lost reverse, second and fourth at the same time while first gear still pulls hard? On a 200-4R from a 1981-1990 Grand National, Regal, Monte Carlo, Cutlass, Caprice or another GM full or mid-size car, that combination sends rebuilders straight to the sun gear shell. This listing is a used GM 200-4R sun shell, listed as the rear planet sun gear and input drum shell: the stamped steel bowl together with the helical sun gear that stands up through its center, cleaned and ready for inspection and install.
The 200-4R is GM's TH200 three-speed with an overdrive planet set, drum and clutches added ahead of it, so behind the overdrive section the power flow is pure TH200. The shell is the connector in that power flow. Tangs around its rim lock into the direct clutch drum, and its splined center drives the rear sun gear. Whatever the direct drum does, the sun gear has to do too. When the 2-4 band clamps the drum in second and overdrive, the shell holds the sun gear still against it. When the direct clutch applies in third, and in Reverse, the shell carries that torque into the sun gear. First gear in Drive is the one range that does not depend on it.
That load path explains the failure. The shell is pressed steel with a splined hub, and every band apply and every reverse engagement twists the hub against the sun gear. On a stock unit the splines wear slowly; on a turbo Buick or a hot-rodded V8 car they can shear in one hard launch in Reverse or one full-throttle 1-2 shift.
Drive it in manual 1 and Drive. If first is solid in both but nothing above first or in Reverse holds, the shell moves to the top of the list. A burned 3-4 clutch or a slipping 2-4 band can mimic part of this, but those normally fail one gear at a time with warning, not all at once. Read our 200-4R 3-4 clutch failure guide to rule that out, and the common problems guide for the band, servo and pressure checks. Once the unit is apart, lock the sun gear in a vise with soft jaws and try to twist the shell; any free play at the splines means it is done.
This is a GM part for the 200-4R built for 1981-1990 cars. The listing gives no donor year or vehicle, and GM revised the shell during production, with later service shells hardened. Rebuilders tell an unhardened shell by how easily a file or scribe cuts the hub; we cannot certify the heat treatment on a used part, so if you are building for high power, test it or plan accordingly. Before ordering, compare the tang count and spacing, the hub spline count and the sun gear tooth count with the shell you removed, or send us your year and VIN. Every 200-4R part we carry is on the 200-4R parts page.
A shell that failed under power has usually sent debris through the cooler. Flush the lines or replace the cooler so the new parts are not fed metal on the first drive.
| Fits | 200-4R |
| Part type | Sun Shell |
| Condition | Used |
| Brand | GM |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
No. This is the stamped sun gear shell with the rear sun gear, the part that links the direct drum to the sun gear. The forward drum is a separate clutch housing with a splined shaft.
All three ranges send torque through this shell into the sun gear. When its splines strip, those gears disappear together while first gear in Drive keeps working.
It is a used GM part and we cannot certify its heat treatment. Rebuilders check by trying to cut the hub with a file; a hardened hub resists it. For high-power builds, test it before installing.
It is listed for the 1981-1990 GM 200-4R. Compare tang spacing, hub splines and sun gear teeth to your old shell, or send us your year and VIN to check.
The thrust washers on both sides, the snap ring if it is distorted, and the clutch frictions and seals. Look over the direct drum slots and the low/reverse carrier too.
