200-4R Input Drum, used and ready to install. Fits the 200-4R. Ships fast from the USA.
When a 1981-1990 Buick Grand National, Regal, Monte Carlo, Cutlass, Caprice or other GM car with a 200-4R suddenly loses reverse and second gear together, or starts throwing steel shavings into the pan, the input drum shell and its rear sun gear move to the top of the suspect list. This listing is a used GM 200-4R input drum shell, sold as an assembly with the rear planet sun gear already in it. It is the bowl-shaped steel shell with the helical sun gear standing up through the center, not the forward clutch drum.
The shell is the bridge between the direct clutch housing and the rear sun gear. Its outer tangs lock into the direct clutch drum, and its center is splined to the rear sun gear, so whatever the direct drum is doing, the sun gear does too. In second gear the 2-4 band clamps the direct drum, and through the shell the rear sun gear is held still so the rear planetary can produce the second-gear ratio. In reverse the direct clutch drives the shell and sun gear. In the upper gears the shell simply turns with the geartrain. Because so many ranges load it, a soft or worn shell is a classic 200-4R weak point, and hot-rodded Grand Nationals find it fast. Rebuilders inspect the shell-to-sun-gear splines on every teardown for that reason.
Those patterns differ from the 200-4R's best-known failure, a burned 2-4 band or 3-4 clutch caused by low line pressure or a misadjusted TV cable. A burnt band slips and smells; a broken shell usually quits outright in the ranges that need it.
Start with the cheap checks. Verify the fluid level, then set or inspect the TV cable, since the 200-4R cable is known to pull out of adjustment at wide-open throttle. Read line pressure at the tap on the left side of the case and compare it to the B&M chart for this unit. If pressure is good in reverse and the car still will not back up, the hard parts in the reverse power path, including this shell, are next. Our 200-4R common problems and fixes guide covers the pressure and TV faults that mimic a mechanical failure, and the 200-4R 3-4 clutch failure guide explains the band and clutch burn pattern. With the pan down, metal without burnt friction material points toward a mechanical break.
This shell fits the GM 200-4R, used from 1981 through 1990 in Buick, Chevrolet, Oldsmobile and Pontiac rear-drive cars. The listing does not state a specific production year, and the shell was revised over the run, including a later hardened version. Compare tang count, spline count and sun gear tooth count against your original, or send us your year and VIN and we will check it for you. Browse every part we carry for this unit on the 200-4R transmission parts page.
| Fits | 200-4R |
| Part type | Input Drum |
| 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 input drum shell that carries the rear sun gear and ties it to the direct clutch drum. The forward clutch drum is a separate part that holds the forward clutch pack.
Yes. It is sold as the shell with the rear planet sun gear installed, as shown in the photo.
It is a GM 200-4R part for the 1981-1990 production run. The listing does not name an exact year, so match tangs, splines and sun gear teeth to your original or send us your year and VIN.
Loss of reverse and second together, a bang followed by no reverse, and steel debris in the pan without the burnt smell of a slipping band or clutch.
DEXRON-VI. GM's fluid guidance says it covers transmissions that specified earlier DEXRON fluids. Do not use DEXRON ULV.
Inspect the rear planetary and thrust washers, replace the 2-4 band and direct clutch frictions if there was debris, and flush the cooler and lines.
