Th400 transmission

GM TH400 Automatic Transmission

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The Novak Guide to the

th400_transmissionThe TH400 is an automatic shift, three-speed, longitudinally positioned transmission. It is widely regarded to be a supremely durable and legendary transmission.

The TH400 is conservatively rated at 450 ft. lbs. of input torque. Aftermarket building techniques take it well past that figure.


The Turbo 400 was introduced in 1964 in Buick and Cadillac cars and in Chevrolet and Oldsmobile cars the following year. An innovative variable pitch stator was available in the 1965-1967 cars that could essentially vary the characteristics of the torque converter.

th400_specsThe TH400 made its way into heavier duty GM trucks in the 1970's in 2wd and 4wd configurations. The 400 was not just a GM exclusive transmission. It is an immensely popular transmission in the automotive industry as well as the aftermarket. They are found in GM's, Jeeps, Jaguars, Rolls-Royces, Ferraris and others.

As with other GM transmissions, GM changed the naming scheme of the TH400 in 1990 and it was then referred to as the 3L80 (3-speeds, Longitudinally positioned, 8000 lbs. GVW). An overdrive version of it was introduced as the 4L80-E. This electronically controlled transmission remains in production and wide use in heavy-duty GM and military applications.


The TH400 and Jeeps have quite a history together. This list is of the Jeep powertrains that had this excellent transmission. The TH400 came in 2wd or 4wd Jeeps, coupled either to the popular Model 20 (or Model 21, in a few rare cases) transfer case or the Quadra-Trac, the latter being an option from 1973 to 1979. The early versions had factory block adapters. Later AMC versions had their own case with no adapter.

  • 1965-1967, 327 V8 (Rambler / AMC)
  • 1968-1971, 350 V8 (Buick)
  • 1969-1972, 225 V6 (Buick)
  • 1972-1975, 232 I6 (AMC)
  • 1975-1979, 258 I6 (AMC)
  • 1972-1979, 304 V8 (AMC)
  • 1972-1979, 360 V8 (AMC)
  • 1974-1975, 401 V8 (AMC)

The 400 transmission has a main case of cast aluminum alloy with a length of 24-3/8" long. Its aluminum case is essentially smooth. The rear mounting face of the transmission has a hex bolt pattern with ribs running forward longitudinally. The fluid pan shape is irregular (see image, left), being likened unto a distorted Texas pattern. The TH400 is the largest of the common GM auto transmissions, but still surprisingly compact in light of the immense power they can handle.

There are two significant variations of the TH400. The TH375 was a version of the transmission used from 1972-1976 in smaller displacement cars. It is identified easiest by its "375-THM" designation cast in the underside of the tail housing. The TH475 was an extra-heavy-duty version, and was found in larger trucks from 1971 on.

th400_top_viewIf you are trying to determine the TH400 from another in a vehicle, a fast way to tell is to look at the kick down mechanism. The TH400 uses an electrical slide switch, which is controlled by the throttle linkage. The TH350 uses a mechanical cable kick-down mechanism that is attached to the throttle linkage.

An interesting variable pitch stator feature of the Turbo 400 was available in 1965-1967 Buick, Olds and Cadillacs. These are identified by the two-prong plug on the case. While 1970-1974 models also had this plug, it is for the transmission controlled spark system.

Transfer Case Adaptability


The Turbo 400 as adapted to a Jeep or IH Dana 20 transfer case.

This transmission makes an excellent conversion transmission due to its adaptability into most Jeeps longer than CJ5s. Both 2wd and 4wd versions of the Turbo 400 can be used equally well, and there are no inherent advantages to either one once you have installed our adapter assembly.

It is of interest that the 1976-1979 AMC case, while more or less similar from the collar of the case, back, is tilted about four degrees. This was presumably for transfer case clearance purposes. Novak's #134 & #141 adapter designs compensate for this clocking to re-level the adapter and mount assembly.

2wd transmissions feature conical shaped tailhousings and an output yoke, which are replaced with a typically shorter 4wd style output shaft (included with our adapter assemblies) of varying lengths and spline counts, depending on the application. The HydraMatic can be adapted to the popular Jeep (and many IH) transfer cases, including the:


A factory Jeep design of the TH400 adapter to the Dana 20 transfer case. OEM adapters are highly prone to breakage. Novak offers a strengthened reproduction of this adapter (#8624113) to replace these broken units, in addition to our superior dual-bearing design #124 adapter kit.

Essentially all factory GM 4wd applications available with an OEM configured TH400 have adapters and transfer cases that are prohibitively long for a Jeep, and transfer cases whose sizes and gearing fall short of desirable for most Jeep applications.

Engine Compatibility and Adaptability


A turn-key TH400, professionally built, OEM style or adapted and delivered to your door - ready for a variety of engines and Jeep transfer cases. Read more...


The front face TH400 is natively compatible with either the Chevy 90 degree “Small Block” & “Big Block” patterned engines (image, left), including the V6, V8, I6 & Iron Duke I4 (the latter mentioned only for accuracy and perhaps some comedy).

These differences only affect the front bell of the case, and all Turbo 400 cases are largely similar from that point back.

Buick / Olsmobile / Pontiac / Cadillac

Buick engines and TH400's are natively compatible when choosing a Buick V8 or V6 version of the transmission. All Buick, Olds, Pontiac and Cadillac TH400's share the same engine pattern, commonly refered to as the "BOPC" pattern.

AMC V8 to TH400 torque converter sizing ring

A part often overlooked by installers is the factory Jeep sizing ring or shim bushing between the TH400 torque converter pilot and the AMC crankshaft bore. This ring is critical for the precise centering of the torque converter to the crank. Failure to install this part can cause front pump failure and other issues.

Novak manufactures and carries this part under Jeep #J5352374 or #5352374, as seen here.

AMC/Mopar Jeep

The first Turbo 400s found in Jeeps had a factory adapter plate, while later AMC versions had a dedicated AMC style case.

The Chevy 400 can be made compatible with AMC I6 & V8 engines. See our Kit #437AMC for details. This conversion can help make for an improved Jeep powertrain over 727, 999, AW4 and other, lesser transmissions.

TH400 Parts 

Novak does carry a full line of parts for the TH400 transmission, including OEM grade and upgrade components for individuals working on their transmissions. If interested, we welcome you to contact us.


A fantastically designed and built transmission, the Turbo 400 is broadly popular for Jeep conversions. They are very servicable, buildable and their strength puts them into the top tiers of Jeep sports and performance applications.



TH400 Transmissions
3 Speed Automatic Racing Transmissions

Note: Any ATI TH400 can be made to PG length for an additional charge. Call and check core availability for 4WD units. Refundable core charge for acceptable transmission core is $175.00, If a SuperCase is used: $100.00

Street/Strip T400 Transmission   Rated up to 600 HP

Auto Function Valve Body
  • Race Clutches and Steels
  • Blue-printed High Flow Front Pump
  • ATI Forward Auto Valve Body
  • ATI HD Sprag Assembly w/steel drum
  • OEM Transmission Pan
  • Ears left on
Add a SuperCase and Chevy Bell - $1,395.

DescriptionHP RatingPart #Price
Chevy Case600HP401000$1,795.00
Chevy Case, DF Bell600HP401000DF$2,095.00

Street Rod T400 Transmission and Converter Combo   Rated up to 600 HP

Save money when you buy your transmission and converter together! Choose from several applications that include an ATI Street/Strip transmissions, a Streetmaster Torque Converter, transmission cooler, a “Trick Stick” locking dipstick and tube and, on non electronic units, a case of ATI’s Super F™ automatic transmission fluid! Other components and a variety of options are also available.

Package Price - $2,495 (Part #401800)

DescriptionPart #Price
T400 Street Strip Forward Auto Transmission401000$1,795.00
Streetmaster Torque Converter408330/40
Polyurethane Transmission Mount206621$37.95
Trick Stick406490$44.95
Cooler with Fan925139$175.00
Cooler installation Kit925132$49.00
Super F ATF - Case 12 quarts100001-12$99.95
Crate Fee $100.00
Core Charge* $175.00
Total if purchased separately--$3,025.85
PACKAGE PRICE401800$2,695.00

Saves $295 when purchasing entire package

OPTION #1 - HD CENTER SUPPORT405471$189.00
OPTION #3 - STL DIR DRUM W/HD 34 ELE SPRAG405681$362.61

* Credit may be obtained for the return of a good core on the T-350 and T-400 Kits    DOWNLOAD CORE CREDIT FORM
OEM case upgrades

For OEM Case T400s, add an SFI Supercase and Chevy Bell at time of build for $1395.

Add ATI's SFI 30.1 Direct Fit Bellhousing installed on OEM case for $349.
 ATI's Direct Fit Bells feature a machined indicating
lip to ensure proper location on machined OEM cases

Competition T400 Transmission  Rated up to 700 HP

Manual Valve Body
· Add a SuperCase and Chevy Bell for $1,395
  • Race Clutches and Steels
  • Blue-printed High Flow Front Pump
  • ATI Reverse Manual Valve Body
  • ATI HD Sprag Assembly w/steel drum
  • OEM Transmission Pan
  • Ears cut off - no inspection pan mounts for ease of installation and header clearance
DescriptionHP RatingPart #Price
Chevy Case, Forward Pattern700 HP401200$1,795.00
OEM Case, Forward Pattern, SFI Direct Fit Bell700 HP401200DF$2,095.00
Chevy Case, Reverse Pattern700 HP401300$1,795.00
OEM Case, Reverse Pattern, SFI Direct Fit Bell700 HP401300DF$2,095.00


Transbrake T400 Transmission  Rated up to 800 HP

Reverse Manual · Add a SuperCase and Chevy Bell for $1,395
  • Race Clutches and Steels
  • Blue-printed High Flow Front Pump
  • ATI Compu-Flow Transbrake Valve Body
  • ATI Heavy Duty Sprag with steel drum
  • ATI Heavy Duty Center Support
  • OEM Transmission Pan
  • Ears cut off - no inspection pan mounts for ease of installation and header clearance

DescriptionHP RatingPart #Price
Chevy Case800 HP401360$2,095.00
OEM Case, SFI Direct Fit Bell800 HP401360DF$2,395.00


Pro T400 Transmission   Rated up to 1,200 HP

Reverse Manual, Good for high HP cars up to 3200 lbs

  • Race Clutches and Steels
  • Blueprinted High Flow Front Pump
  • Heat-treated Stator Tube, pinned
  • Roller Bearings
  • ATI Reverse Manual Compu Flow Valve Body
  • ATI Severe Duty Alum Direct Drum One-year warranty on Drum Assembly
  • 300M Input Shaft with OEM steel drum
  • 300M Intermediate Shaft
  • Heavy Duty Steel Forward Clutch Hub
  • Heavy Duty Center Support machined for faster transbrake and bronze support bushing
  • Heavy Duty Clutch Packs
  • -6 AN Fittings (in Supercase units)
  • High Flow Filter
  • Deep Aluminum Cast Transmission Pan
  • 2.48 Low Gear-helical

DescriptionHP RatingPart #Price
OEM Chevy Case1,200 HP401550$2,895.00
OEM Case - SFI Direct Fit Bell1,200 HP401550DF$3,295.00
SFI SuperCase & Chevy Bell1,200 HP401550SC$4,395.00
Transbrake - OEM Case1,200 HP401555$2,995.00
Transbrake - OEM Case, SFI Direct Fit Bell1,200 HP401555DF$3,395.00
Transbrake - SuperCase & Chevy Bell1,200 HP401555SC$4,495.00


Fuel Comp T400 Transmission   Rated up to 1,500 HP

Reverse Manual, Good for high HP cars up to 3600 lbs

  • Race Clutches and Steels
  • Blueprinted High Flow Front Pump
  • Heat-treated Stator Tube, pinned
  • Roller Bearings
  • ATI Reverse Manual Compu-Flow Valve Body
  • ATI 36 Element Severe Duty Aluminum Direct Drum
    • billet aluminum piston
    • Steel sleeve for Teflon ring use
  • 1 year warranty on Drum Sprag Failure in drag cars
  • Vasco Intermediate Shaft
  • Heavy Duty 1045 Steel Forward Clutch Hub
  • Heavy Duty Center Support machined for faster transbrake and bronze support bushing
  • Increased Clutch Capacity / Heavy Duty Clutch Packs
  • 6 AN Fittings in SuperCase units
  • Deep Aluminum Cast Transmission Pan
  • 2.48 Low Gear-helical
DescriptionHP RatingPart #Price
OEM Chevy Case1,500 HP401600$2,995.00
OEM Case- SFI Direct Fit Bell1,500 HP401600DF$3,295.00
SFI SuperCase & Chevy Bell1,500 HP401600SC$4,495.00
Transbrake - OEM Case1,500 HP401603$3,395.00
Transbrake - OEM Case, SFI Direct Fit Bell1,500 HP401603DF$3,595.00
Transbrake - SuperCase & Chevy Bell1,500 HP401603SC$4,695.00

COPO Spec T400 Transmission
Now you can order a T400 with the same specifications used in the new COPO Camaro
  • Aluminum Forward and Direct Drums
  • ATI Reverse Manual Valve Body
  • ATI SFI T400 Supercase
  • Roller Bearing Tail housing
  • Transmission Catch Can
DescriptionPart #Price
Naturally Aspirated
Aluminum Direct Drum with 34 element sprag and Aluminum Forward Drum with 300M input
Vasco input and intermediate shafts, hardened stator tube, 36 element severe duty direct drum

DescriptionPart #Price
2016+ COPO Naturally Aspirated Package401651GM$5,295
2016+ COPO Supercharged Package401656GM$5,845

2016+ COPO Packages include Quick Disconnect Cooler Lines, Lokar dipstick, Polyurethane mount, catch can, 2 gallons of Super F ATF and shipping crate



COPO Camaro Specs from GM:PDF

Mopar Gen III HEMI T400 Transmission
Rated to 1500 HP and bolts directly to your Gen III Hemi


These transmissions are assembled in ATI’s SFI case with an SFI Mopar specific bellhousing. The appropriate flexplate, crank adapter and required bolts are also included so a standard GM converter with a small bolt circle drops right in. Standard gear ratio is the OEM 2.48/1.48. Core charge and shipping crate are included in the price of these transmissions.

  • Exclusive billet aluminum with 36 element sprag
  • Compu-Flow Reverse Manual Transbrake
  • Roller bearing tailhousing
  • Vasco input and main shaft
  • Deep aluminum pan
  • LOKAR firewall mount dipstick
  • 10 quarts of ATI’s 30W Super F synthetic fluid

DescriptionPart #Price
New Gen HEMI Trans, SuperCase & ATI HEMI Bell *
New Gen HEMI Trans, SuperCase & Dual Starter Packets in HEMI Bell * 401641$6,650.00

* Includes an 8” (#408900) or 9”(#408930) Fuel & Blown Converter.
For a 10” Fuel & Blown (#408420), add $100
For a 10.0/10.5 Fuel & Blown (#408421/#408424), add $500

3-Speed Max Duty Outlaw T400 Transmission
ATI Aluminum Transbrake, 1800 HP as equipped or up to 3500 HP depending on options
  • Race Clutches and Steels
  • Increased clutch capacity in all positions - Up to 9 forward, 8 direct and 6 intermediates
  • Blueprinted high-flow front pump with heat-treated tube or ATI Super Pump
  • Billet aluminum safety reverse transbrake valve body (band apply option available)
  • ATI Severe Duty 36 element alum direct drum with billet piston
  • Vasco intermediate shaft
  • 1” Vasco input shaft with new lightweight steel drum & billet piston
  • 4140 HT steel forward clutch hub
  • HD center support
  • HD cast aluminum bearing tail
  • New billet aluminum reverse servo cover
  • Deep aluminum cast pan
  • -6 AN fittings
  • Lokar® direct mount dipstick


DescriptionInputGear RatioGear TypePart #Price


SuperCase & Chevy Bell - 5 pinion planetary
1" Vasco2.48 1.48 Helical Cut401605SC$6,595
SuperCase & Chevy Bell - 6 pinion aluminum carrier1" Vasco2.10 1.40 Straight Cut401609SC$8,495
SuperCase & Chevy Bell - 6 pinion aluminum carrier1" Vasco1.95 1.34Straight Cut401607SC$8,595
SuperCase & Chevy Bell - 6 pinion aluminum carrier1" Vasco1.86 1.31Straight Cut401608SC$8,695
SuperCase & Chevy Bell - 6 pinion aluminum carrier1" Vasco1.60 1.26Straight Cut401610SC$9,595
SuperCase & Chevy Bell - Includes 1.125 main shaft, 300M Output and sheet metal pan - 1.51 / 1.26 Available with large main only! Add $1501-3/16" 300M1.60 1.26Straight Cut401611SC$13,295

Optional HD 300M output shaft recommended for vehicles over 3,000 lbs (with BBC) or 3,200 lbs (with SBC)



Convert your ATI T400 to Lock-Up starting at $1995

3-Speed Max Duty Outlaw Lock-Up T400 Transmission

DescriptionLock UpMain ShaftOutputGear RatioGear TypePart #Price


SuperCase & Chevy Bell1"300M1.86 1.31 Straight Cut401608LU*$10,195
SuperCase & Chevy Bell - includes sheet metal pan.
1.125"300M1.60 1.26Straight Cut401611LU*$14,495
Add a standard welded Lock Up converter for $2,750 or a bolt together Lock up converter for $3,750
ATI's welded Outlaw Lock-Up Converters provide 0% slip for up to 2800 HP while the Bolt Together Lock Up Converter will provide 0% slip all the way up to 4500HP. Both converters feature 5-axis billet aluminum back cover, dual o-ring sealing, optional Nissan style pump and multiple stator designs. A bronze pilot option is also available. 

 2-Speed Max Duty Outlaw T400 Transmission

  • Race Clutches and Steels
  • Increased clutch capacity in all positions - up to 9 forward, 8 direct and 6 intermediates
  • Blueprinted high-flow front pump with heat-treated tube or ATI Super Pump
  • Billet aluminum safety reverse transbrake valve body (band apply option available)
  • Vasco intermediate shaft
  • ATI Severe Duty 36 element alum direct drum with billet piston
  • 1” Vasco input shaft with new lightweight steel drum & billet piston
  • 4140 HT steel forward clutch hub
  • HD center support
  • HD cast aluminum bearing tail
  • New billet aluminum reverse servo cover
  • Deep aluminum cast pan
  • -6 AN fittings
  • Lokar® direct mount dipstick


As horsepower gets easier and cheaper to make and racers set the bar higher and higher, a need is created for numerically lower gear sets with higher strength requirements. Today’s high HP racer needs a durable transmission with a less aggressive starting line ratio. Most racers achieve this by converting the Turbo 400 transmission to a 2-speed unit allowing them the ability to leave off the transbrake in 2nd gear. ATI now has an answer for this market and offers three variations of a 2-speed Turbo 400! OEM cased units are rated to 1800 HP and not intended for heavy weight cars. ATI SuperCase recommended over 2000 HP!

2-Speed Max-Duty Outlaw T400 Transmission 1,800 to 3,000 HP Max rating, depending on options

Description Case BellLow Gear Gear TypePart #Price
Direct Fit
SFI Chevy Bell
1.57Straight Cut401612DF$5,395
SFI Chevy Bell
1.57Straight Cut401612SC$6,995
Direct Fit
SFI Chevy Bell
T400 MAX DUTY 2-SPEED OUTLAW SFI SuperCase SFI Chevy Bell1.48Helical
T400 MAX DUTY 2-SPEED OUTLAW SFI SuperCase SFI Chevy Bell1.40Straight Cut401616SC$7,895

Optional HD 300M output shaft recommended for vehicles over 3,000 lbs (with BBC) or 3,200 lbs (with SBC)



Brake in 1st and 2nd. Choose any Wicked Quick Transbrake available at no charge on Max Duty units.

1-2 Reverse Manual Transbrake, PRN 123, No Band Apply



1-2 Reverse Transbrake P(RN)123N, No Band Apply Clean Neutral



T400 Build Options - Prices good only on installed items
T400 SuperCase w/Chevy Bell 400011


T400 Wicked Quick Valve body -


HD Center Support with Bronze Bushing 405471


HD Steel Fwd Clutch Hub 405370


HD Steel Fwd Clutch Hub - 1045 Material 405371


HD Lightweight Steel 405370LW


Alum Direct Drum w/34 elem 405722


Severe Duty Alum. Direct Drum 407056


300M Input w/Forward Drum 406000


Vasco Input Shaft w/Fwd Drum 406001


4340 Input w/ Alum Drum (1000 HP Max) 406004


Vasco Input w/Alum Fwd Drum 406005


Trigger Ring, ATI Drum only 407265


Vasco intermediate shaft - Carries 1 year warranty for up to 2000HP - ATI Clutch hub 405370 required 405970V


300M Output with bushing, std length 406025


300M Output with bushing, PG length 406025P


Roller tailhousing-aftermarket OEM Length 401935


Roller tailhousing-aftermarket - PG Length 401936


Bolt Together Aluminum Pump 405038


Adjustable Regulator Kit 405183


Lokar Direct Mount Dipstick 406492


Lokar Firewall Mount Dipstick 406493


Trick Stick bell mount 20" forward bend 406490


-6 AN trans cooler line fittings 925137


-8 AN trans cooler line fittings 925138


Jiffy Tite Cooler Line Kit 925170


Transmission Catch Can 406611


Polyurethane Trans mount 206621


Moroso Deep Sheet Metal Pan 403610


ATI Sheet Metal Deep Pan 403612


Deep Aluminum Cast Pan 403500


Black Magic™ Lock-Up Components
Attention transmission builders! If you are a qualified transmission builder, ask about our new line of Lock-Up transmission components for the T400. In order to be considered for this program, you must be a qualified performance business located at a commercial location. A business license and Tax ID number are required. Please note: Lock up parts are not returnable and not for individual sale!

Description Part #
Lock Up Super Pump, OEM Shaft with adjustable pressure regulator405038L
Lock Up Super Pump, Big Shaft with adjustable pressure regulator4050358L
Input Shaft, 300M Big, Lightweight 4140 Heat-Treated Steel Forward Drum with Aluminum Piston406002L
Input Shaft, Vasco Big, Lightweight 4140 Heat-Treated Steel Forward Drum with Aluminum Piston406002LV
Input Shaft, 300M Big, Aluminum Forward Drum with Steel Insert406003L
Input Shaft, Vasco Big, Aluminum Forward Drum with Steel Insert406003LV
Input Shaft, Vasco OEM, Aluminum Forward Drum with Steel Insert406005L
Input Shaft, Vasco OEM, Lightweight Steel Forward Drum Aluminum Piston406006L
Lock up Hose and Solenoid Kit403172
Cooler Pressure Dump Hose and Solenoid Kit

Designed for use with ATI Aluminum Valve Bodies*. Must add one of the following:


405153KD Converter Dump (Big Shaft)

405153LD Converter Dump (Big Shaft) Lock Up

405133D Converter Dump with stator tube/plate assembly (OEM shaft)

405133LD Converter Dump with stator tube/plate assembly (OEM shaft) Lock Up

*Note: Wicked Quick® Valve Bodies are ready to use. Case modifications are required.

T400 SuperCase
®Transmission Case

Awarded SEMA's Best New Racing & Performance Product for 2013

The new cast aluminum T400 SuperCase is the result of over 2 years of development. Designed in-house at ATI, and cast here in theUSA, and machined at ATI on 4-Axis Horizontal CNC machines, the T400 SuperCase features improved fluid pathways to assure better performance and will accept any of ATI’s SFI bellhousings, along with the Reid bell (with slight modifications) and Browell cans.



Heavy-duty 356-T6 cast aluminum case meeting SFI 4.1 specs with no internal or external shield needed
Made in the USA and machined in-house at ATI using only two fixturing set-ups to provide optimum accuracy
Accepts OEM pans, extension housings and 99% of all stock internal components
CNC machined minimum depth valve body passages yield extremely fast transbrake releases and quicker shift times

Accepts all current ATI Super Bells for many engines and other bells on the market

Features additional center support lugs to provide additional 2nd gear strength, with a modified pressure plate supplied
Provisions for three extra bolts added to help secure the center support and intermediate pressure plate
Increased thickness extension housing/output shaft bearing area provides extra support for 4x4 units
Roller bearing for output shaft (bushing available by request)
Cooler lines are 1/4" NPT to accept PG quick-connect lines and other popular cooler hoses and fittings


Part Number


ATI T400 SUPERCASE - Chevy Bell and Transmission Case



ATI T400 SUPERCASE - Heavy Duty Chevy Bellhousing ONLY - no case



ATI T400 SUPERCASE - Heavy Duty Chevy Bellhousing ONLY - 1" deep - for Lock-Up



ATI SUPERCASE - TH400 - Case Only



ATI SUPERCASE - TH400 - Case with Ried bell pattern machine casting






ATI SUPERCASE - TH400 - Tailhousing w/ roller bearing - OEM Length



ATI SUPERCASE - TH400 - Tailhousing w/ roller bearing - PG Length









T400 SuperCase Bell Packages - Include Bell, flexplate, adapter and hardware. Option prices listed are available only at the time of order or while your T400 is being built.
SB Mopar, New Gen HEMI 202801


SB Mopar, New Gen HEMI - Dual starter pocket 202804


BB Mopar, 6 Bolt 202802


BB Mopar, 8 Bolt 202803


SB Ford, 157 Tooth 202810


SB Ford, 157 Tooth - Ext Balance 28 oz 202801-28


SB Ford, 157 Tooth - Ext Balance 50 oz 202801-50


SB Ford, 164 Tooth 202811


SB Ford, 164 Tooth - Ext Balance 28 oz 202801-28


SB Ford, 164 Tooth - Ext Balance 50 oz 202801-50


BB Ford, 164 Tooth, Internally balanced 202813


BB Ford, 164 Tooth, Externally balanced 202814


Toyota 2JZ - Requires ATI 8" or 9" Converter202820



TH400 Parking Pawl Pin
ATI's Parking Pawl Pin for T400 transmissions. With this new, hard to find replacement pin and clip, there will be no more headaches from digging through old cases for rusted up used pins! The new hardened steel pin comes standard on ATI’s T400 Supercase Transmission builds and is engineered to original GM specs.


Part Number





T400 Roller bearings

Part #


TH400 - BEARING - DIRECT DRUM - Used in between the reverse ring gear and output for OEM and between the cut forward clutch hub and direct clutch drum (optional build)



TH400 - BEARING - CENTER SUPPORT TO SUN GEAR - For use between the center support and sun gear (OEM applications)



TH400 - BEARING - REAR INTERNAL GEAR - For use between the bottom of the sun gear to rear planetary ring gear on all Turbo 400 units



TH400 Shift Shaft Kit
Shift shafts in T400 transmissions can become corroded in harsh environments. This direct replacement piece is yellow zinc plated for maximum corrosion protection. Includes serrated flange nuts for improved holding capacity.


Part Number





Park Pawl Release Spring


Part Number





Spring for Manual Valve Lever


Part Number





Park Pawl Actuator Rod
ATI's new T400 Park Pawl Actuator Rod is an all new piece that replaces the OEM unit.


Part Number





Park Pawl Guide Plate
ATI's new T400 Park Pawl Guide Plate is an all new piece that replaces the OEM unit.


Part Number





Modulator Plug Clamp
ATI's new T400 Modulator Plug Clamp is an all new piece that replaces the OEM clamp on T400 valve bodies.


Part Number






TH400 Center Support
The upgraded center support for the Turbo 400 features a bronze bushing that virtually eliminates premature sprag failure. It is highly recommended for competition applications.

Also available with Teflon coating for aluminum drums


Part Number





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Overview of the GM TH400 Transmission

The GM TH400 Transmission: An Overview - Gearstar

 The TH400 or Turbo 400 is a good transmission that was used in several cars years ago. This popular transmission was found in GM’s cars, as well as, Rolls-Royces, Jeeps, Jaguars, Ferraris, etc. The TH400’s high-level of adoption could be tied to its remarkable features, and it proved that people can once again rely on GM transmissions.

But what were these features sported by this durable and legendary transmission, and generally, what set it apart from other transmissions from this manufacturer? An overview of the TH400 transmission will give you a better idea. Read on to find out!


The GM TH400 Transmission

The GM TH400 transmission is a three-speed automatic transmission that was longitudinally positioned behind the engine. This placement is aimed at providing the best power ratio and durability for rear-wheel drive. The TH400 has been rated at 450 ft. lbs. of input torque, nonetheless, aftermarket designs that have been modified may go beyond that rating.


History of the TH400 Transmission

The TH400 was launched by General Motors in 1964, as a replacement to the ST300 2-speed automatic transmission. It was used in a wide range of vehicles, hence, it was not just exclusive to GM cars.

Upon its launch, the TH400 was evident in Buicks and Cadillacs, and a year later, it was used in Chevrolet and Oldsmobile cars. Buick, Olds, and Cadillacs that were later launched between 1965-1967 also featured the transmission but with an innovative variable-pitch stator. This stator helped to vary the torque converter’s characteristics, and you can tell a car has this stator by the two-prong plug on the case.

In the 1970s, the TH400 was used in heavier-duty GM trucks and it was available in 2wd and 4wd configurations. The naming of the TH400 was changed to 3L80 (3-speeds, Longitudinally positioned, 8000 lbs. GVW or Gross Vehicle Weight) in 1990 to make it easier for buyers to identify the transmission.

The change in naming does not come as surprise since some GM transmissions were also renamed (for example the 700R4 to 4L60). Around the same time when the TH400’s name was changed, an overdrive version called the 4L80-E was launched.

This is an electronically controlled transmission that is still being produced and used in a range of heavy-duty GM and military cars/trucks. Generally, here’s a list of cars that used the TH400 transmission:

    • 1965-1967, 327 V8 (Rambler/AMC)
    • 1968-1971, 350 V8 (Buick)
    • 1969-1972, 225 V6 (Buick)
    • 1972-1975, 232 I6 (AMC)
    • 1975-1979, 258 I6 (AMC)
    • 1972-1979, 304 V8 (AMC)
    • 1972-1979, 360 V8 (AMC)
    • 1974-1975, 401 V8 (AMC)
    • GM
    • Jaguar
    • Ferrari
    • Rolls-Royce


Features of the TH400 Transmission

The features of the TH400 Transmission enabled it to provide improved performance over previous transmissions. It was also durable, and these characteristics can be tied to the following:

    • Aluminum and iron construction.
    • Weighs 135 pounds without fluid.
    • Bell housing integrated into the transmission.
    • First gear: 2.48:1, Reverse gear: 2.08:1, and third gear is an even 1 to 1.
    • Came with three tail shaft lengths.


Turbo 400 Transmission Identification

The Turbo 400 transmission can be identified in the following ways:

1. External Build

The TH400 transmission comes with a case made of cast aluminum alloy to give it strength and durability. The case is very smooth and its length sits at length of 24-3/8″ long. This TH400 is the largest of the common GM automatic transmissions, however, the transmission still maintains a compact design.

There is a hex bolt pattern on the rear mounting face of the transmission and the ribs run forward longitudinally. In line with that, the fluid pan has an irregular shape.

2. Variants of the TH400

There are two variants of the TH400, and these are the TH375 and TH475. The TH375 was used in smaller displacement cars between 1972-1976. In contrast, the TH475 was used in larger trucks from 1971 since it is an extra-heavy-duty version. One can easily different either these variants apart by looking out for the “375-THM” designation cast on the bottom of the tail housing.

TH350 vs. TH400

A simple way to differentiate them is to check the kick-down mechanism. The TH400 transmission takes advantage of an electrical slide switch controlled by the throttle linkage. On the other hand, the TH350 uses a mechanical cable kick-down that is connected to the throttle linkage. Despite the difference, the TH400 is considered the heavy-duty version of the Turbo-Hydramatic 350.


Transfer Case of the TH400 Transmission

The TH400 can easily be adapted for use in most Jeeps longer than CJ5s, and as such, it is an excellent conversion transmission. Whether it’s the 2wd and 4wd versions of the Turbo 400, either of these can be used. Nonetheless, the 1976-1979 AMC case is similar to that of the TH400’s, from the collar of the case and back, however,  it is tilted about four degrees.


Engine Compatibility and Adaptability

The engine compatibility and adaptability of the TH400 transmission include:

1. AMC/Mopar Jeep

The earliest Turbo 400s in Jeeps featured a factory adapter plate, whereas older AMC versions came with a dedicated AMC style case. It is entirely possible to make the Chevy 400  compatible in the AMC I6 & V8 engines. As an upgrade of this nature can result in a more enhanced Jeep powertrain over 727, 999.

2. Chevrolet

The front face of the TH400 is compatible with the Chevy 90 degree “Small Block” or the “Big Block” patterned engines.

3. Buick / Olsmobile / Pontiac / Cadillac

The TH400 is compatible in Buick engines especially when you use a Buick V8 or V6 version of the transmission.


Common TH400 Problems

The TH400 may have offered improved performance over its predecessor, the ST300, but it still came with its own problems. Notable among this is an early shift and less efficiency when the engine revs high. The latter occurs when the kick-down switch, responsible for shifting between gears and maintaining maximum RPMs, stops working. The switch would’ve helped in, efficient power usage.

On the other hand, the cause of this problem can be tied to the wrong placement of the vacuum hard-line, moving from the intake manifold with a pliable rubber line. The heat generated by the engine and transmission leads to the deformity of the rubber, thereby failing to hold the pressure properly. Another problem of the TH400 is the possibility for its transmission fluid to leak gradually into the hose if the seal is not fixed properly.


The Bottom Line

An overview of the TH400 transmission shows it is a durable transmission that can give a good performance. The TH400 was used in a wide range of cars from GM as well as other manufacturers. Interestingly, the transmission can be adapted for use in several engines today. In the end, whether it’s a new or aftermarket TH400 you settle for, you are bound to get the full benefits offered by this transmission.




Motor vehicle

Turbo-Hydramatic or Turbo Hydra-Matic is the registered tradename for a family of automatic transmissions developed and produced by General Motors. These transmissions mate a three-element turbinetorque converter to a Simpsonplanetary geartrain, providing three forward speeds plus reverse.

The Turbo-Hydramatic or Turbo Hydra-Matic (THM) series was developed to replace both the original Hydra-Matic models and the BuickDynaflow. In its original incarnation as the Turbo-Hydramatic 400, it was first used in the 1964 model year in Cadillacs. The Buick version, which followed shortly thereafter, was known as the Super-Turbine 400. By 1973, THM units had replaced all of GM's other automatic transmissions including Chevrolet's Powerglide, Buick's Super Turbine 300, and Oldsmobile's Jetaway. Starting in the early 1980s, the Turbo-Hydramatic was gradually supplanted by four-speed automatics, some of which continue to use the "Hydramatic" trade name.

Although the Turbo Hydra-Matic name alludes to the original Hydra-Matic developed by General Motors' Cadillac division in the late 1930s, the two transmissions were not mechanically related.

Super Turbine 400 / THM400 / THM375 / 3L80 / 3L80HD[edit]

Turbo-Hydramatic 400 Transmission

The THM400 can be visually identified by an oil pan number four shown at General Motors Transmission Pans. First introduced for the 1964 model year under the name "Turbo Hydra-Matic" in Cadillacs and "Super Turbine" in Buicks. The following year, application expanded to Oldsmobile and Pontiac and to some full-sized Chevrolets. Many of the Buick, Cadillac, and Oldsmobile THM400s produced between 1964 and 1967 were equipped with a "Switch-Pitch" torque converter with a 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 narrow front pump spline. Externally the switch pitch version has two electrical connections, where the non-switch pitch THM400 has only one. GM used a Switch Pitch torque converter in the Buick twin turbine Dynaflow transmission between 1955–1963 and the Super Turbine 300 two speed transmissions used by Oldsmobile, Pontiac (Pontiac's ST300 didn't have a switch pitch), and Buick divisions between 1964 and 1967. This transmission (among other THMs) is identified by the "Park R N D L2 L1" selector quadrant. The switch pitch is not the only THM400 that utilizes an external 2 prong connector. Other units to include the 2 prong connectors had an internal pressure switch that was used to control spark timing retard. All THM400 units had a 32 spline output shaft with the exception of the THM375 that used a 27 spline output.

A variant of the THM400 known as a THM375 is a THM400 with a mid length 27 spline output shaft that mates to the smaller THM350 27 spline drive shaft yoke. It can be identified by "375-THM" cast into the tailhousing. Internally the clutch packs originally had fewer friction plates. THM375s were found in some 1971-76 Buick Lesabres and Oldsmobile Delta 88s with the 5.7 liter V-8. Somewhere in the Mid-80's Chevrolet C10 Pickups could also come equipped with a THM375. It is a THM400 Chevrolet bolt pattern case that has a longer 27 spline output shaft and matching extension housing with "TH375" cast into the housing. Some "Heavy Duty" THM350s were also designated THM375-B. Another variant is the 3L80HD, often 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. The THM425 front wheel drive transmission shares almost all its internal parts with the THM400. Checker Motors Corporation Motor Company used the Chevrolet version of the THM400 for its "A" series taxi and Marathon models until the end of production in 1982.

By 1980, the relatively heavy THM400 was being phased out of usage in passenger cars in response to demand for improved fuel economy. The THM 400 was utilized in the C- and K-series (full-size) Chevrolet/GMC pickups and G-series (full-size) vans until 1990 when GM switched over to the 4L80E. Today, the United States ArmyHMMWV 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.

Through the end of the '70s substantially more CBOP (Cadillac/Buick/Oldsmobile/Pontiac) bellhousing THM400s were produced than any other THM400. Chevrolet bellhousing THM400s, while not rare, can be hard to find and are, as a result, usually more expensive to buy (they were commonly found in 3/4 ton (8500 GVW and above) Chevrolet/GMC trucks and vans (includes the P-series box vans and 1983-86 CUCVs) when RPO M40 was checked off the option list - especially when coupled to a 454 - usually in HD applications including the C40-C60 medium duty trucks where a bolt-on output shaft is used in place of a slip yoke) - when used with passenger cars it was usually coupled to a Mark IV engine or some high performance small blocks (e.g. the 1970 LT-1). The THM400 was never produced with a multicase bell housing.

Other auto manufacturers have used the THM400 and its 4L80E successor, including Ferrari (in the 400/412); Jaguar/Daimler (in pre-1994 XJ12 and XJ-S coupes and their Daimler stable mates); Rolls-Royce (in 1965–1980 Silver Shadow and 1980-1992 Silver Spirit series cars, along with their Bentley stable mates); the Nissan Prince Royal; AM General; and Jeep (usually found in the FSJ pickups and SUVs). Early Jeep THM400s used an adapter between the engine and transmission bell housing while later models had an AMC specific housing - which bolted to its inline six and V8. Though identical except for the bell housing pattern used through the '60s and ending in 1979 the THM400 was mated to the Dana model 18,20 and was the only transmission used with the Borg-Warner 1305/1339 all-wheel-drive transfer case used only in Jeeps (AMC/Jeep phased in the used of the Chrysler Torqueflite 727 after 1979 until the FSJ platform was phased out), It has been known to adapt a THM400 to other engines using adapters.

THM400 transmissions are very popular in automotive competition due to their great strength. Much of this strength comes from the use of a cast iron center support to suspend the transmission's concentric shafts that join the clutch assemblies to the gear train. The center support, which is splined to the interior of the transmission's case, also provides a robust reaction point for first gear (the gear train's reaction carrier is restrained from counter-rotating the engine in first gear by a roller clutch whose inner race is part of the center support). Since the first gear reactive force is evenly distributed around the periphery of the case, the types of mechanical (and some times violent) failures that have plagued other competition transmissions[vague] are rare.

The THM400 was the first three-speed, Simpson-geared automatic to use overrunning clutches for both first and second gear reaction, a feature that eliminated the need to coordinate the simultaneous release of a band and application of a clutch to make the 2-3 gear change. Owing to this feature, as well as the use of a large, multi-plate clutch to provide second gear reaction, the THM400 is able to withstand very high input torque and an enormous number of shifting cycles, as would be encountered in frequent stop-and-go driving. As a result, it has met with considerable success in commercial vehicle applications.

For 1987, GM changed the nomenclature of their Turbo Hydramatic transmissions — the THM400 was renamed '3L80' (three forward speeds, longitudinal positioning, and an arbitrary strength rating of 80, the second highest such rating assigned). The 3L80HD was introduced in 1987 as the HD unit used in passenger trucks. In 1991, a four-speed overdrive version, the 4L80-E, replaced the THM400 in Chevrolet/GMC pickups, vans, SUVs, and commercial vehicles. The 4L80E (and its successor 4L85E) was the first Hydramatic to incorporate electronic controls — almost all of the THM400/3L80/3L80HD's components are interchangeable.

Transmission fluid cooler line connections are found on the right-hand side of the THM400. The lower connection is the cooler feed, and the upper connection is the return.[1] The case is tapped for either self-sealing 1/4"NPT fittings, or 1/2"UNF fittings with a washer seal. 5/16" or 3/8" rigid coolant lines are generally connected via appropriate double-flared adapters.

Four-wheel drive truck applications used 3 various shorter output shafts that coupled with a female transfer case input shaft. Early transfer cases mated directly to the THM400 with a cast-iron adapter, usually a vertical oval shape. Later models used a circular style iron adapter which is generally considered the stronger of the two. The shortest was used with the NP203 transfer case.

Gear Ratio


The Turbo Hydra-matic 350 was first used in 1969 model cars. It was developed jointly by Buick and Chevrolet to replace the two-speed Super Turbine 300 and aluminum-case Powerglide transmissions. So, although it carries the Turbo Hydra-matic name, the Hydra-matic Division of General Motors had little, if anything, to do with its design. The 350 and its 250, 250C, 350C and 375B derivatives have been manufactured by Buick in its Flint, Michigan plant, and by Chevrolet in Toledo and Parma, Ohio and Windsor, Ontario.

The THM350 was also regarded as a 'three speed Powerglide' and during its development, was generally called this. Although it uses the same torque converter as the THM400 (without variable pitch stator) it has a familial resemblance to the 1962-73 aluminum Powerglide from Chevrolet[according to whom?] and was largely derived from the Chevrolet design. An important difference in the THM350 compared to the THM400 is that there is no fixed center support midway through the geartrain; this difference in layout would have permitted the THM350 to be adapted to the Corvair where the drive and driven ends are the same, but this feature was not exploited. Air-cooled versions (with a baffle on the torque converter and air intakes cast into the bellhousing) of the THM350 appeared mid-1972 in the Chevrolet Vega and Nova 6.

One THM350 weak point was excessive end-play between the pump and center support and resulting wobble of the direct clutch drum due to both the end play and use of a relatively narrow bushing in the drum. This weak point can be addressed by using an extra thrust washer between the planetary gear and direct clutch to remove the end play and using a wider aftermarket bushing in the direct clutch drum.[according to whom?] Another weak point is the relatively thin center support and the lightweight matching splines in the case. This weakness can be addressed by using an inexpensive aftermarket case saver kit.

Four-wheel drive truck applications for the THM350 used an iron adapter that mated it to the transfer case directly, similar to the THM400. The THM350 adapter was cast iron and used a sliding sleeve to couple the transmission output shaft to the transfer case input shaft with a steel coupler sleeve that was splined to accept both shafts and couple them together. An internal snap ring inside the coupler sleeve controlled the sleeve's position on the shafts, with circular seals in the adapter sealing the transmission from the transfer case.

For the 1981 model year, a lock-up torque converter was introduced which coincided with the new EMC control of most GM cars; this version is the THM350-C, which was phased out in 1984 in GM passenger cars for the 700R4. Chevrolet/GMC trucks and vans used the THM350-C until 1986. The lock-up torque converter was unpopular with transmission builders B&M Racing once marketed a conversion kit for THM350-Cs during the early 1980s until the advent of high stall lock-up torque converters when its overdrive counterpart (THM700R4/4L60) were modified. The standard TH350 is still very popular in drag racing.


The THM250 is a derivative of the THM350 and was introduced for 1974 in Chevrolets as a Powerglide replacement. Internally, the THM250 is a THM350 without the intermediate clutch pack and with a band adjuster similar to the Powerglide. The THM250 was usually coupled to smaller displacement engines - the largest a third generation Chevrolet inline six found in the Nova and Camaro (1974 and 75 model year only). During the 1976 model year the THM250 was phased out of production, replaced with the lighter duty THM200. It was later reintroduced in 1979 as the THM250-C in the wake of the failure-prone THM200/200C - the later 250C was further lightened with the use of a sun gear shell used with the THM350 but with 3 holes to reduce rotating mass and the low/reverse piston with 8 cutouts.

Gear Ratio


A THM 200 transmission, produced between 1975 and 1987

After the 1973 OPEC oil embargo, GM developed a lighter-duty version of the THM350 with lightened materials — primarily alloys in place of ferrous materials (e.g. clutch drums and oil pump) — the Turbo-Hydramatic 200. The THM-200 was first used in 1976 models including GM's T-cars (which includes the rebadged Isuzu Gemini sold through Buick dealers as the Buick/Opel by Isuzu), X-cars, and some Isuzu automobiles (Chevrolet LUV and Isuzu P'up). However, this transmission was notorious for its failure rate[citation needed] when used behind too large an engine - the largest being the Oldsmobile 5.7 L diesel. No multicase bellhousings were used - bellhousing patterns included Chevrolet V8, Buick-Oldsmobile-Pontiac, Vega 4, GM 60 degree pattern (includes the Tech IV), and Isuzu G engine.

It was GM's first transmission which used a throttle valve cable (similar in design to the Chrysler Torqueflite part throttle kickdown linkage) controlling the shift points and part throttle kickdown. This setup was later incorporated into the THM700R4.

Starting with the 1979 model year, vehicles which had the THM-200/200C as standard equipment were optioned with the THM250-C, which is a THM-350 without the intermediate clutch pack along with an adjustable band similar to the Chevrolet Powerglide. Also in the 1979 model year, the THM-200 received a lockup torque converter, and some internal components (primarily the low/reverse clutch drum and planetary gears) were later shared with the Turbo-Hydramatic 200-4R. The low/reverse sprag (roller clutch) assembly was also shared with the 1988-04 Chrysler Torqueflite 904 (also 30, 31, 32RH) and its derivatives e.g. the A500 and 42RE. THM200/200Cs were produced until 1987.

Gear Ratio


For the 1981 model year, the 200-4R was introduced. The components which were prone to failure in the THM200 were improved, and in the later 1980s this transmission was used with high-power applications — primarily the Buick Grand National and the 1989 Pontiac Firebird Trans Am Indy 500 Pace cars. The 200-4R was configured with several different torque converters depending on the vehicle application.

Unlike the 700R4, most 200-4Rs have a multicase bellhousing for use with Chevrolet, Buick/Olds/Pontiac (BOP), and Cadillac engines. However, 200-4Rs share mounting locations with the TH-400. Since the external dimensions are similar to the TH-350 (overall length, drive shaft yoke spline count/diameter and general size), 200-4Rs are often swapped in place of TH-350s in older vehicles to provide an overdrive gear. Early models had a "PRND321" shift indicator, while later models used "PRN(D)D21," with the left D identified as the overdrive gear by a square or oval ring.

The THM200-4R can be found in the following vehicles:

The THM200-4R was phased out after 1990; its final usage was in the GM B-body vehicles.

Gear Ratio

THM700R4 / 4L60 / 4L60E / 4L65E / 4L70E[edit]

See also: GM 4L60-E transmission

The four-speed Turbo Hydra-Matic 700R4 was introduced for the 1982 model year for use in Chevrolet/GMC vehicles.

In 1990, the Turbo Hydra-Matic 700R4 was renamed the 4L60. Under the new designation, the "4" stands for the number of forward gears, the "L" for longitudinal applications (rear-wheel-drive), and the "60" is the strength rating (less than the 4L80). "60" is the relative torque value. For example, 80 is stronger than 60, which is stronger than 40, etc. A 4L80-E can handle more torque than a 4L60-E. The "E" denotes electronically controlled shifting. The 4L60 however is hydraulically shifted based on governor pressure and throttle valve (TV) cable position. 1992 was the last year of widespread usage of the 700R4 (4L60). The 1993 Camaro, Corvette and Typhoon were equipped with the last production 700R4. The last design change of the 700R4 was an added checkball to the valve body. In 1992 electronic controls were added, and it became the 4L60-E. The 4L60E is not easily swapped with the 4L60, as the 4L60E depends on a powertrain control module (PCM) to shift.[2] The 4L60E went into service in trucks, vans, and SUVs in 1993 and in all RWD passenger cars (Corvette, F and B/D bodies) in 1994. In 2001, an updated version — the 4L65-E, was introduced. Five-pinion planetaries, along with a strength-improved output shaft, were improved to withstand the 300+ lb·ft (400+ N·m) of torque of the 6.0 Vortec engine. The 4L70E transmission is the same as a 4L65E with a speed sensor located in the pump.

700R4 / 4L60 / 4L60E / 4L65E / 4L70E / technical description[edit]

The Turbo Hydra-Matic 700R4 can be identified by an oil pan number six shown at General Motors Transmission Pans.

The tailshaft housing is held onto the main case by four bolts (the bolt spacing is similar to the THM350), and uses a square-cut o-ring seal, and not a gasket. The typical width of this transmission where it bolts to the engine is 20 in (51 cm) overall. From the engine/trans mating surface to the cross member mount bolt is 22.5 in (57 cm), and engine/trans surface to output shaft housing mating surface is 23.375 in (59.37 cm) overall, with the tail shaft housing typically measuring 7.625 in (193.7 mm). External dimensions are similar to a THM350 with a 9-inch tailhousing found in Chevrolet/GMC long wheelbase truck/vans and 1971-76 B-bodies (Bel Air, Impala, Caprice).

Transmission fluid cooler lines on the 700R4 the bottom fitting on the right side of the transmission is the "out" line to the cooler and the top fitting is for the return line from the cooler. These fittings are .25 in (6.4 mm) pipe thread, and can include an adapter from the factory for threaded steel lines in a SAE size. 4L60Es manufactured after 1995 use snap-in connections instead of threaded. The original version of the transmission had a 27-spline input shaft (shared with the THM200C and 2004R) which was a common failure point. In 1984, the 700R4 designed for use behind Chevrolet small block V8s received a 30-spline input shaft similar to those found on TH400 transmissions and which also used a different torque converter than its 2.8 V6 and 2.2 L4 engines. Between 1984 and 1987, internal components, from the ring gear to the oil pump housing, were updated, ending with the auxiliary valve body for 700s manufactured after October 1986.

In 1995, the 4L60E received a PWM-controlled lockup converter. The early designs simple on or off lockup function while the later design can regulate the apply pressure as to not feel the lock up occur. GM added a fifth solenoid to the valve body, called the PWM solenoid. In 1996, GM introduced a redesigned 4L60E transmission case that incorporated a bolt-on bellhousing and a six-bolt tail housing. This two-piece case style was first seen in 1996 and up model S-10 Blazer, S-10 pickup, GMC Jimmy, and GMC Sonoma with the 4.3 L engine. The majority of 1998 and later applications of the 4L60E were two-piece cases (i.e. a removable bellhousing). Both transmissions are the same internally. The non-PWM (1993-1994) style 4L60Es are not interchangeable with PWM-style (1995 and later) 4L60Es. Also in 1996, GM changed the 3-2 solenoid to a different style which makes it not interchangeable with any previous models. For the model year 1996 GM trucks, there were two versions of the 4L60E: one had a bolt-on bellhousing, the other did not. In total, there are nine different bolt-on bellhousings. The bolt-on bellhousings used on the 4.3 L V6 and 1996-2002 GEN I+ versions of the small-block Chevrolet V8 used the same bellhousing. These had one from 1996 to 1997 and then a slight redesign for 1998. The LSx engines used a longer one to accommodate a redesigned torque converter, commonly referred to as a 300mm converter, with a longer pilot nose (GM sells an adapter assembly for using the LSx 4L60Es when used with an early engine). There are two bellhousings for the Holden GM models. One for the Corvette drivetrain. One for the S/T platform with 2.2L and 3.8L engines. And finally, two for the S/T platform with the 2.8L, 3.5L and 4.2L engines (one used in 2002 and the other from 2003 and on).

Gear Ratio

700R4 / 4L60 / 4L60E / 4L65E /4L70E applications[edit]


See also[edit]


External links[edit]


Transmission th400



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