The TH400 is an aluminum cased three speed automatic transmission that was produced by GM. It was introduced for the 1965 model year and made its debut in Cadillacs, and is respected for its durability and adaptability. The TH400 came in two wheel drive and four wheel drive vehicles, passenger cars and heavy duty trucks, as well as GM vehicles and those made by other manufacturers.

• Street Rodder C4 Transmission '70-'82 (289, 302, 351C, 351W) Small Bellhousing Bolt Pattern (sold separately) SKU 511238. Wish List Compare. 1997-2006 4L80E StreetFighter Transmission. Full Manual Competition 4x4 TH400 203 NP Transfer Case Non Lock-Up (All Chevrolet) SKU 212615.
• The TH400 is an early model, non-computer-operated transmission widely sought after by car enthusiasts for its internal strength. The fact that it is not electrically actuated by solenoids means it requires other apparatus to regulate shift points. Simply put, an automatic transmission.

The TH400 is a three-speed automatic transmission that is longitudinally positioned behind the engine. The aim of this kind of positioning is to provide the best power ratio and durability for rear-wheel drive. 11 product ratings - 1964-UP GM CHEVY TH400 TURBO 400 TRANSMISSION VALVE BODY #8626577A $85.00 Trending at $86.66 Trending price is based on prices over last 90 days. The TH400 is an aluminum cased three speed automatic transmission that was produced by GM. It was introduced for the 1965 model year and made its debut in Cadillacs,.

T400 Transmission Pan

More than almost any transmission ever made, it has found its way into a wide variety of vehicles outside of the GM family. The TH400 has appeared in Jaguars, Hummers, Ferrari’s, and many more.

TH400 Specs

3L80

In the early 90’s GM rebranded all of their transmissions, They created a standardized naming system across their product line, and changed the name of the TH400 to 3L80.. The 700R4 became the 4L60 and so on. There is no difference other than the name. 3L80 stands for three gears, longitudinal mount (rear wheel drive), and the 80 signifies that it can handle 8000 lbs. in gross vehicle weight(supposedly).

Note that unlike all the other GM transmissions of the time there was no E at the end of the nomenclature. This is because the TH400 was never designed to communicate with the CPU of the vehicle/The 3L80 was the last non overdrive transmission used by GM in regular production trucks and vans. It was eventually replaced by the 4L80E. It uses the B-O-P bellhousing bolt pattern which makes it compatible with nearly any GM engine. It also does not use a locking torque converter.

Th375 and Th475

There are were a few one of versions of the Turbo 400 as well. These are the TH375, and the TH475. The Th375 was manufactured for cars with low horespower engines in the 1970’s. It was modified to fit the TH350 driveshaft yolk. If you are looking to purchase a TH400 avoid it. It’ll have The TH475 was used in heavy duty trucks in the 1970’s, and can handle a lot of power.

TH400 Identification

If you were to line up every automatic transmission that GM ever produced, you’d be hard pressed to find one that is larger than the turbo 400. It is just huge. If it was lined up with a 200-4R, TH350, or 4L60E it would be easy to identify a TH400. It would be far and away the largest transmission there.

Since it’s not very likely that you are going to run into a lineup of automatic transmissions being the biggest isn’t going to be very helpful.

There are 13 bolts on the pan underneath the transmission. If you count 13 you are almost home free, but the Th350 also has 13. Since these are the two most common GM automatic transmissions of the latter half of the last century it’s very important that you figure out which is which.

The TH400 uses an electronic kick-down mechanism, which means that there will be an electric plug on it. The TH350 uses a mechanical linkage that attaches to the carburetor. Th350 has the vacuum modulator in the back, and the TH400 keeps it on the side.

Using the pan bolt pattern is the easiest way to identify the TH400. Both the TH350 and TH400 have a similar look. They utilize a kick down cable, and they both use the same bellhousing bolt pattern. Identifying the Th400 is really as easy as knowing the differences between it and the TH350.

Also, take a look at the bolt pattern itself. The Th400 has a much more complex pan then the Th350. The Th350 is basically a square with a corner taken out of it. See for yourself. The TH400 on the other hand has 9 different angles on the the pan. It’s one of the more complex pans that GM made.

The Turbo 350 has a much simpler look. Here it is, Notice that it looks like a box with a slice taken out of the corner. That corner would be on the driver’s side of the vehicle.

T400 Transmissions

Identifying Turbo 400 By the Tag

You’ll find the identification tag above the transmission pan on the drivers side. It is machined into the transmission in most cases. So, it’s really not really a tag, which can make it a bit more difficult to identify if the transmission is really greasy. Take some brake parts cleaner with you if you really want to get a good look at it.

Try using this guide to help you lock down what model number you may be looking at.

Common TH400 Problems

• Early Shift– One of the most common issues with the TH400 is that it’ll shift too early. This is almost always cause by the vacuum line that runs to the modulator from the intake manifold. While they came from the factory with hard lines, many people will swap them out for soft lines when doing a swap, since finding a hard line for the particular vehicle can be an issue.
• Late shift– The Th400 will often shift a little later than a person would like, espescially at the track. This is usually caused by its electric kick-down switch.
• General not shifting right– If you’ve checked that the kick down circuit is ok, and the vacuum line is too, than it may be time to look at the vacuum modulator itself. It’s more likely to have fluid in it than it is to have gone out itself.

TH400 and Non-GM vechicles

Maybe the best compliment comes from your competition. And at least a dozen auto makers have paid GM to use the TH400 instead of creating a competitor for it. These include Toyota, Ferrari, Rolls-Royce, and Hummer. This is a true testament to its bulletproof reliability and ease of tuning.

The Turbo 400 has been used in Jeeps from the factory. Early model AMC Jeeps used an adapter plate to mate it with the GM bellhousing bolt pattern. Later, a specific TH400 was made just for Jeep. This version tilted the transmission about 4 degrees in order to better accommodate the transfer case. It has not been produced for quite a while and is considered pretty rare. The Turbo 400 is compatible with most Jeeps. However, the CJ5 has to narrow of a wheelbase to accommodate it. The specialty jeep TH400 case is 24 1/2 inches long.

When looking at a Jeep that came from the factory with the Turbo 400, it’ll be bolted to either the BW 13-39 or the Dana 20 transfer case. In the 1960’s some Jeeps came with Buick engines, so they used neither an adapter nor the Jeep specific transfer case. Some of the AMC specific adapters on these transmissions have been prone to failure.

TH400’s are what we cut our teeth on. We have extensive experience building the TH400 for all types of applications. We do stock rebuilds all the way up to 3000+ HP Pro-Mods. Our “stock” rebuild is strong enough for over 600 HP repeatedly yet functions like a stock transmission. Our TH400’s use exclusive proprietary parts that are only available in our builds as well as techniques that your normal transmission shop or builder is likely not aware of.

We specialize in building TH400’s for forced induction street driven applications where the customer wants the comfort of retaining the automatic shifting features. Many builders don’t know how to make the trans live with boost and still shift automatically, so they recommend a full manual valve body. We have automatic shifting TH400’s in turbocharged applications approaching 1000 HP. We also cater to you Ford guys. If you need a stout TH400 for your Mustang, Lightning, or other Mod Motor or SBF, BBF combo, give us a call. We prefer you call in before ordering so that we can help you select the transmission that best meets your needs.

Our Stage I TH400’s are an upgraded build. These are designed to replace a daily driver TH400 behind a stock or near stock engine and have increased service life due to our hydraulic, mechanical, and lubrication upgrades. They don’t shift brutally hard; we are able to keep them reliable by using many of the features GM designed into them. Crisp shifts at part throttle progressively getting firmer with throttle. Very streetable and very reliable.

As with all Jake’s Performance transmissions, they start with a select core that is disassembled, the case is blasted clean, hot tanked, pressure washed, inspected, painted and prepped for reassembly. They also include all new friction clutches, bands, steel plates, soft parts, filter, modulator (if applicable), as well as hydraulic upgrades, bearings added at several thrust locations, and other modifications depending on power level.

Although we use the build levels and options below, each transmission is custom built for the application. That is why we have a lead time. There are too many variations to try to keep these on the shelf.

Large diameter input shafts and other options for 2000+HP combos are available. Call for a custom quote.

Our Stage 1 TH400 is a heavy duty rebuild with valve body and hydraulic improvements, rollerized rear thrust, heavy duty intermediate snap ring, and OEM pan. 450 HP/TQ capable but proven at much higher HP levels.

Our Stage 2 TH400 includes all the components in the Stage 1 rebuild but is upgraded to a 34 element sprag and the corresponding direct drum, 6 clutch direct with carbon based frictions, 4 clutch intermediate, manual/automatic valve body or forward pattern full manual upon request. Aluminum Deep pan and additional modifications. 750 HP/TQ capable.

Stage III TH400 has all the features of the Stage II but includes a billet input shaft, and forward hub. Deep cast aluminum pan is standard. 1000+ HP/TQ capable. The Griner* Aluminum Transbrake with or without safe neutral is an optional upgrade.

Stage 4 TH400 has all the features of the Stage III but includes the 36 element Super Drum and alloy intermediate shaft for more reliability at power levels over 1000 HP.

Stage 5 TH400 uses a Griner* G20 billet Aluminum valve body and eliminates the intermediate sprag. Great setup for 1500+ HP combos.

We’re offering a 2 speed TH400 for big power and drag radial applications. This build utilizes a new SFI case and bellhousing, aluminum direct drum, fully rollerized with several weight saving and drag reducing internal modifications, alloy input and intermediate shafts, alloy steel forward hub, billet aluminum transbrake valve body, and fabricated aluminum pan standard. Super Shaft large diameter input shaft is optional. Forward Shift Pattern (P-R-N-2-1) with safe neutral.

This transmission is designed for the racer looking to maximize efficiency and reduce weight. Great for grudge racers, class racing, and anyone looking for that competitive edge. This build has become one of our most popular due to its exceptional value and approximately 20 lbs lighter weight.

The base model will utilize an OEM case and tailhousing. It includes an aluminum forward and direct drum, aerospace material input and intermediate shafts, alloy forward hub, deep aluminum pan, lightened OEM ratio (2.48) gearset, ALL thrust washers replaced with torrington bearings (fully rollerized), and aluminum valve body.

Options include other ratios, Reid SFI case, roller bearing tailhousing, small diameter drums, and other valve bodies.

Due to the many variations in options, please call for a quote for your custom build.

We offer a TH400 setup for Rockcrawler and off-road applications. This is similar to our Stage I build but uses a HD “K” case 4×4 TH400 core with a reverse pattern manual valve body that retains engine braking. We can upgrade this unit to our other level of builds as necessary for you big power off road guys. Price is $2500.

This build is based on our standard Stage 2 build. It starts with a 4×4 core and HD case (subject to availability). We use a reverse manual valve body with engine braking, a wider 1.25″ intermediate band for engine braking with HD material. A 34 element sprag, offroad specific clutch materials, lubrication modifications, and torrington bearing upgrades are added. Upgrades are available for bigger power combos. Price is $2650.

We’ve pulled out all the stops on this build. It is built specifically for the harsh conditions experienced in offroad competition. We start with a new Reid Racing case for a bulletproof foundation to prevent stress cracks and case failure common when used in rough terrain and/or with a transfer case attached. We include a Reid Super Bellhousing and a new roller tailhousing (where applicable). The next key ingredient to this package is the spragless design used instead of the typical roller clutch or sprag design used for 2nd gear. This requires the state of the art billet aluminum Griner* valve body to control shift timing and includes a direct drum assembly that eliminates the failure prone sprag. An important additional benefit of this design is the extremely strong engine braking ability. Most TH400’s with engine braking rely on the OEM design 1″ wide band. This does not, it uses the entire 2nd gear clutch pack to give the same capacity and strength to engine braking as it does acceleration. Additionally we use 300M input shaft with larger splines in the forward drum, 300M alloy intermediate shaft, and billet alloy steel forward hub. We add torrington needle bearings in several key locations to deal with friction and thrust loading caused during heavy deceleration. We make several lubrication improvements, pump modifications, and other improvements to help with lubrication and cooling issues seen in offroad competition. As always, all new clutches, steels, bands, and soft parts. Clutches are specific design that we use for offroad builds. Custom length output shafts and planetary ratios are available. 6 month warranty. Pricing begins at $8000.

Additional upgrade parts are available such as custom billet converters, CSR SuperShields, 2.10 or 2.75 gearsets, and various case upgrades. Visit our online store for options and pricing.

Shipping is $250 within the continental United States (restrictions may apply).

*Griner Valve Bodies are no longer available but alternative options may be discussed.