TH400 Input Drum, remanufactured and ready to install. Fits the TH400. Ships fast from the USA.
This is a bare TH400 input drum: the forward clutch housing with the turbine (input) shaft already in it, and nothing else. It is the part a rebuilder needs when the old housing has a cracked piston bore, chewed lug slots or scored seal surfaces, or when the turbine shaft has twisted or stripped its splines behind a high-stall converter. If you are chasing a Turbo 400 that lost Drive but kept Reverse, or one that sheared the input shaft at the drag strip, this is the core piece you build the forward clutch back onto with your own plates, piston and hubs.
In the TH400 the turbine shaft runs from the converter turbine back through the pump cover and is pressed into the forward clutch housing, so this drum spins with the converter whenever the engine runs. Its job is to hold the forward clutch: the piston and 16 release springs live inside it, the plates ride in its inner lugs, and when line pressure strokes the piston the clutch locks the housing to the forward clutch hub and the mainshaft. The forward clutch is applied in every forward range and released in Reverse and Neutral. The back of the housing also drives the direct clutch hub. Because all engine torque in first gear goes through this shaft and drum, the shaft is the weak link in a high-horsepower build, and Transmission Digest has covered heavy duty and extreme duty replacement shafts made for that reason.
A sheared or stripped turbine shaft gives no movement in any gear, including Reverse, and the shaft will turn freely once the converter is out. A drum problem usually leaves Reverse intact. Check fluid level and line pressure first, because low pressure or broken pump hub sealing rings will also burn forward plates. Our TH400 delayed engagement guide covers that test sequence, and the TH400 common problems guide covers what fails under added power. On the bench, GM's manual has you inspect the housing for wear, scoring, open oil passages and a free check ball, and the shaft for open lube passages, good splines, undamaged bushing journals and no cracks or distortion.
The listing is a TH400 forward drum with input shaft and is not tied to a narrower year range. TH400s were built from 1964 through 1990, and turbine shaft length and spline count need to match your converter and pump, so set your old shaft next to this one and compare length, splines and the check ball location before you install it. The safest route is to send your year and VIN or the transmission ID plate before ordering. If you need a drum that comes already loaded with plates, piston and hubs, see our TH400 forward drum assembly for 1964-1990. All of our parts for this unit are on the TH400 parts page.
A bare drum needs fresh plates and seals. The TH400 master overhaul kit brings forward, direct and intermediate clutches, and the TH400 overhaul kit covers the seals and gaskets.
| Fits | TH400 |
| Part type | Input Drum |
| Condition | Remanufactured |
| 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.
No. It is the bare forward clutch housing with the turbine shaft installed. The piston, release springs, plates, hubs and seals are not included, so plan on a rebuild kit or reuse good parts from your old drum.
Yes. GM lists the turbine shaft and forward clutch housing as separate service parts, and stronger aftermarket shafts are sold for high-horsepower builds. This listing comes with a shaft already installed in the drum.
Maybe. Losing every gear including Reverse often points to a sheared turbine shaft, broken converter drive or no pump pressure. Losing only the forward gears points more to the forward clutch. Check line pressure first, then pull the converter and see whether the shaft turns freely.
It is a TH400 forward drum with input shaft. Compare the shaft length and spline count with your old one, or send your year and VIN or ID plate number and we will confirm it before shipping.
At minimum the piston seals, center seal, forward clutch plates and pump hub sealing rings. If the old drum failed from burned plates, inspect the pump and the direct drum too, and flush or replace the cooler before refilling with Dexron.
