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TH400 Level 1 - To 450 HP

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250.00 LBS
Calculated at checkout

*Image is a representation of this item. Actual item may vary.

Product Description

TH400 Level 1 - Starting at $2,000 - Call for quote

Horse Power: 450
(Up to 425 ft-lbs Torque)
Converter: 12” or 13” Heavy Duty High Performance Furnace Brazed
Stall: 1600-2200

Master Overhaul Kit with High Energy Frictions and All New Steel Plates

High Flow Filter

New Kickdown Solenoid

Adjustable Modulator

Transgo Shift Kit

New Front Band

New Borg-Warner Low-Reverse Band

New Torrington Bearings

Bushing Kit with Flanged No Walk-Out Case Bushing

Thrust Washer Kit

New Low-Reverse Spring & Roller

High Capacity Direct Clutch Drum

Heavy Duty Forward Clutch Hub

High Volume High Flow Pump Assembly with New Gears

New Chrome Transmission Pan with Drain Plug

New Speedometer Drive Gear

New Speedometer Driven Gear

20,000 GVW Hayden Transmission Cooler


The THM400 (or the Turbo 400, which it is called by drag racers and car enthusiasts) is a three-speed automatic transmission that was first introduced at the beginning of the 1964 model year in Cadillacs and Buicks (under the name Super Turbine 400). The following year, use expanded to Oldsmobile and Pontiac and to some full-sized Chevrolets (usually coupled to the Mark IV big-block V8). It can be identified by an oil pan in the shape of what some would call similar to that of the state of Texas.

Many of the Buick, Cadillac, and Oldsmobile THM400s produced between 1964-67 were equipped with a torque converter that incorporated the Switch-Pitch variable-pitch stator, which is sought after by collectors and drag racers. These can be identified outside the vehicle (with the torque converter removed) by a noticeably narrower front pump spline. Externally the switch pitch version has two electrical connections, where the non-switch pitch THM400 has only one. GM originally used a Switch Pitch torque converter in the Buick twin turbine Dynaflow transmission between 1955-1963. It was also used in the Super_Turbine_300 two speed transmissions used by Pontiac, Oldsmobile, and Buick divisions between 1964-1967. (The Super_Turbine_300 was used in 1968-1969 without the Switch Pitch torque converter.)

One variation of the THM400, known as a THM375, is simply a THM400 with a long output shaft that mates to the smaller THM350 drive shaft yoke. This can be identified by "375-THM" cast into the tailhousing. Internally the clutch packs originally had fewer friction plates. Some "Heavy Duty" THM350s were also designated THM375-B — the key to telling the difference is the shape of the pan. Another variation is the 3L80HD, which is sometimes referred to as a Turbo 475. The 3L80HD has a straight-cut planetary gear set. There is no externally visible way to determine whether the transmission contains the straight-cut planetary gear set. Some think units with an extra deep oil pan are 3L80HDs, but that's not a reliable indicator. The THM425 front wheel drive transmission shares almost all its internal parts with the THM400.

By 1980, usage in GM passenger cars was on a decline because of the 1973 Arab Oil Embargo, when the Hydramatic 200-4R and 700R4 overdrives were phased in. The Presidential Limo (a modified 1984 Cadillac Fleetwood Brougham) used during the Reagan Administration was the last known GM passenger vehicle to use the THM400, alongside the C- and K-series (full size) Chevrolet/GMC pickups and G-series (full size) vans ending in 1986 thereafter it was renamed to the 3L80. Today, the United States Army HMMWV is the only vehicle using the THM400. The civilian Hummer H1 originally had the 3L80s, but the current model has had a 4L80E since the mid-1990s.

All package include;

Torque converter

Dipstick tube  seal and indicator

Bell housing hardware

Torque converter bolts

Dust covers

Neutral safety switch

Trans selector lever

2wd trans includes yoke


Trans electronics if purchased with engine package

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