Performance Transmissions: TH350 Vs TH400 Vs 4L60E Vs 700R4

Navigating through the history of General Motors, one cannot help but marvel at the evolved engineering of automatic transmissions. These transmissions are not just a part of the vehicle; they are the heart of performance, each with a distinct tale. The TH350 and TH400 emerge from the core design of the Hydramatic—GMC’s original powerhouse that launched an era of automotive prowess.

With the TH350, you have the basic technology perfected over eighty years, still running strong in classic Oldsmobile models, while the TH400 brings a contrast in performance, designed to withstand the high demands of gasoline engines. Moving to the 4L60E, it’s the 700R4 redefined, embedding the finesse of electronic control to General Motors’ robust lineup. As an automotive enthusiast, I’ve seen these models compare on the streets and tracks, their specs tested, their mettle proven.

Whether cruising with the reliable TH350, commanding the powerful TH400, or harnessing the sophisticated 4L60E and 700R4, the best choice is a homage to your driving narrative—each model a chapter in the legacy of General Motors, who pioneered the path of transmission excellence starting back in 1940.

Salient Features
GM TH350 / Turbo 350Reliability: Renowned for durability and dependability.Versatility: Adaptable for everyday driving and competitive drag racing.Enduring Legacy: Represents GMC’s engineering prowess for nearly two decades.
GM TH400 / Turbo 400Robust Build: Recognized for sturdy construction and long-term reliability.Durability: Significant upgrade over predecessors, for high-powered engines.Smooth Power Delivery: Optimized for rear-wheel drive vehicle performance.
GM 4L60EElectronic Control: Transition from hydraulic to electronic for precise shifts.Versatile Performance: High torque capacity suitable for a variety of models.Fuel Efficiency: Overdrive and refined gear ratios for better fuel economy.
GM 700R4Advanced Overdrive: Improved gear ratios for driving efficiency.Diversity: Compatible with a broad range of GM models.Enhanced Torque Capacity: Beefier input shaft options for higher torque.

GM TH350 / Turbo 350 

Let’s revisit the dawn of automatic-shift technology. Unveiled in 1969, this 3-speed Turbo Hydra-Matic became the staple for Chevrolet trucks and cars, renowned for its solidness and reliability. Not just for daily drives, its 2.52:1 first gear ratio made it a hit in drag racing, offering swift initial momentum.

GM TH350 / Turbo 350 
GM TH350 / Turbo 350 

My experience with the TH350 confirms GMC’s dedication to sophisticated engineering. It’s been a preferred transmission for small-block and V6 engines in various models, from Buick to Chevy, exemplifying standardized excellence. This popular transmission, which replaced the two-speed setups, has been acclaimed for boosting power and enhancing rear-wheel-drive performance.

The THM350 stands as a testament to GMC’s advanced automatic transmission development, setting the foundation for successors like the 4L60E and shaping modern automotive evolution. It marks a significant era from 1969 to 1984, a lasting legacy of GMC and Chevy’s commitment to progression.

GM TH400 / Turbo 400

GM TH400 / Turbo 400
GM TH400 / Turbo 400

In the arena of General Motors transmissions, the TH400, affectionately known as the ‘Turbo 400’, is often hailed as the titan of three-speed automatics. Since its debut in 1964, it has propelled everything from Chevrolet muscle cars to Cadillac luxury sedans, and even Ferrari and Jaguar sports cars, with a robust build and reliability that quickly made it the default transmission for long-term use. Known for its durability, the TH400 was a significant upgrade from the Oldsmobile ST300 two-speed, offering a smooth power delivery that was essential for rear-wheel drive vehicles. Unlike its predecessor, the TH350, the TH400 was constructed to handle the might of big blocks without a hitch, setting a new standard with its longitudinally set layout. Even as General Motors brought out newer models like the 700R4 and 4L60E, the Turbo 400’s foremost status remains unchallenged, a testament to the engineering prowess of its era, and an enduring legacy in the world of automatic-shift transmissions.

GM 4L60E

GM 4L60E
GM 4L60E

Merging the legacy of the 700R4 with modern electronic precision, GM’s 4L60E represents a pivotal shift in automatic, 4-speed transmissions. This longitudinally mounted unit, which emerged in 1993, boasts an overdrive and a suite of five gears, offering a blend of fuel efficiency and performance. It took the foundational 4L60—itself a rechristened 700R4—and infused it with a computerized edge, courtesy of its powertrain control module and digital speed sensor. Tailored for Chevy’s small-block engines, it features a bolt-on bell housing that adapts to diverse setups, a testament to its versatility.

My time under the hood has revealed the 4L60E as a powerful ally, capable of handling up to 450 HP and 425lb/ft of torque, making it a favorite for both enthusiasts and technicians alike. Its design has evolved from the lightweight 3-speed predecessors, now offering forward and reverse gears that respond with intuitive precision, a leap from the mechanically-operated systems of yesteryear. General Motors’ relentless endeavour to improve has certainly paid off, turning the 4L60E into an existing standard for modern vehicles that demand both robust capability and digital adaptability.

GM 700R4 

GM 700R4 
00R4

In 1982, GM unveiled the 700R4, an overdrive transmission set to replace the THM350. This four-speed, automatic-shift marvel phased out its predecessor by 1984, offering upgraded mechanics and advanced architecture for better fuel efficiency. Its higher 1st gear ratio of 3.06 was a game-changer, significantly improving acceleration compared to the 2.52 ratio of the past. The 700R4 came in dual variants, with the earlier editions boasting a 27-splint shaft, while the latter variant introduced a giant input shaft with 30 splints, enhancing the torque management. GM’s concerted efforts to refine automotive engines led to a transmission that was longitudinally placed for optimal performance in Chevrolet and GMC pickup models.

From personal tinkering, I found the 700R4 to be an adaptable fit not just for new trucks and cars but also an excellent upgrade for older Chevy models, giving them new life. It seamlessly boosted the driving experience without the need for complex modifications, making it a popular choice for those looking to replace a worn-out system. The 700R4, often synonymous with the Turbo Hydra-Matic series, remains a testament to GM’s legacy—produced to propel automotive progression and installed to last.

Comparison Chart: TH350 vs Turbo 400 vs 4L60E vs 700R4

TH350TH4004L60E700R4
Identification13 bolts13 bolts16 bolts16 bolts
Ratios1st: 2.52:1<br>2nd: 1.52:1<br>3rd: 1.00:1<br>Reverse: 2.07:11st: 2.48:1<br>2nd: 1.48:1<br>3rd: 1.00:1<br>Reverse: 2.07:11st: 3.059:1<br>2nd: 1.625:1<br>3rd: 1.00:1<br>4th: 0.696:1<br>Reverse: 2.294:11st: 3.059:1<br>2nd: 1.625:1<br>3rd: 1.00:1<br>4th: 0.696:1<br>Reverse: 2.294:1
Types3 speed automatic transmission3 speed automatic transmission4 speed automatic overdrive transmission4 speed, overdrive automatic transmission
Applications1969 – 1986 GMC, Chevrolet cars and trucks<br>(as well as vehicles from other divisions of General Motors)1964 – 1990 GMC, Chevrolet cars and trucks, as well as vehicles from other divisions of General Motors<br>1982 – 1990 C/K series pickups (6.2L diesel, 3/4 and 1 ton models)1982 – 1998 Chevrolet/GMC K10/K1500, C10/C1500, pickups & Suburban (1/2 ton only)1982 – 2012, various GMC, Chevrolet, and Buick applications
Case MaterialAluminum, 1 piece case casting with integral bellhousingAluminumDie cast aluminumCast aluminum
Case to ext. Housing21.75″24 3/8″23.375″23.375″
Overall LengthShort tail: 27 5/8″<br>Long tail: 30 5/8″Short tail: 28 1/4″<br>Long tail: 34″30 3/4″30 3/4″
Bellhousing to mountShort tail: 20 3/8″<br>Long tail: 20 3/8″Short tail: 26 3/4″<br>Long tail: 28″22 3/8″22 3/8″
Weight~ 120 lbs~ 150 lbs w/ ATF~200 lbs dry~ 200 lbs dry
Fluid TypeDEXRON ATFDEXRON automatic transmission fluidACDelco DEXRON VI automatic transmission fluidDEXRON VI


4L60E vs. 700R4 vs. Turbo 350 vs. Turbo 400: Differences Explained

Turbo 350 (The Rugged): 

Diving into the GM transmission spectrum, the Turbo 350 (TH350) emerges as a testament to the era when auto transmissions were all about rugged simplicity. With its vacuum modulator valve strategically placed at the rear end of the main casing, the TH350 boasts a square-shaped oil pan—a distinctive GM design with a chamfered corner on the passenger side. This transmission has propelled countless Chevrolet classics with an assurance of durability and reliability. As a mechanic and a GM enthusiast, I’ve often admired the TH350 for its no-nonsense approach to power delivery, a quality that has made it a beloved fixture in GM’s lineup. It’s more than just a gearbox; it’s a piece of automotive history that’s as dependable today as it was decades ago.

Turbo 400 (The Mighty):

The GM’s mighty Turbo 400 (TH400), you encounter a transmission that’s as robust as the vehicles it powers. Known for its built-in vacuum modulator valve, the TH400 is positioned on the passenger side of the casing, a detail that speaks volumes about its design philosophy. Unlike its relatives, it employs a mechanical cable kick-down system, a departure from the electrically powered sliding switch that characterizes its THM400 predecessor. This piece of engineering is a favorite among enthusiasts for its responsiveness and the surety it brings to high-powered applications. In my personal experience with rebuilding GM classics, the TH400’s reputation for dependability in transferring engine power efficiently is well-earned, marking it as a stalwart among transmissions.

THM700R4 (The Pioneer):

When exploring the THM700R4, it stands out in GM’s transmission history for its innovative approach to overdrive. Introduced as an early version with a four-bolt rear output, the 700R4 marked a departure from its predecessors, offering drivers a new level of efficiency and gear range. In my journey through the evolution of automotive transmissions, the 700R4 always represented a leap towards the future—a differentiating factor that reshaped the expectations of performance. Its design catered to the demands for a more versatile and fuel-efficient ride, setting a new benchmark in the transmission domain and solidifying itself as a cornerstone of GM’s engineering achievements.

4L60E (The Evolution):

The 4L60E transmission is a marvel in the GM lineup, standing as a sophisticated successor to the earlier models. It distinguishes itself with a six-bolt hex rear output, a feature that sets it apart from the predecessors like the 700R4. This latter iteration represents a leap in GM transmissions, incorporating both the resilience of its forebears and the innovative spirit of modern engineering. My hands-on experience with the 4L60E has shown it to be a paragon of adaptability, seamlessly fitting into a range of GM vehicles and confidently handling the demands of both performance enthusiasts and daily commuters alike.

Gear Ratios – Mastering the Drive:

The gear ratio in a vehicle is a critical piece that strikes a fine balance between torque and speed—a fundamental trade-off. From a resting position, the need for power is paramount to get the wheels in motion, while accelerating on the highway requires more speed than force. In the grand chess game of automotive design, the choice of these ratios defines the character of a vehicle—whether it’s leisurely cruising or spirited performance. The TH350 and TH400 stand on this spectrum as robust contenders, optimizing this balance to serve everything from daily commutes to the demands of the track. The 4L60E and 700R4, with their overdrive capabilities, push the envelope further, offering a broader range of speed and efficiency that redefines the driving experience.

TransmissionGear RatiosApplicationsFeatures
TH3501st: 2.52, 2nd: 1.52, 3rd: 1.00, Rev: 2.07General use in Chevrolet/GMC vehicles, suitable for lighter vehicles not requiring high torqueReliable, durable, easy to service
TH4001st: 2.48:1, 2nd: 1.48:1, 3rd: 1.00:1High-performance and heavy-duty vehicles, requiring more power to handle greater torqueRobust, high torque capacity, suitable for high power engines
700R41st: 3.06:1, 2nd: 1.63:1, 3rd: 1:1, 4th: 0.7:1, Rev: 2.9:1Vehicles that benefit from overdrive for efficiency and controllable speeds, like Chevrolet Blazer/GMC JimmyFuel-efficient with overdrive, adaptable
4L60E1st: 3.06:1, 2nd: 1.62:1, 3rd: 1.00:1, 4th: 0.70:1Modern vehicles requiring sophisticated transmission control, like sports cars and passenger vehiclesElectronically controlled for precise shifts, modern performance needs

Transmission Types:

The TH350: A Three-Speed Classic

The TH350 is GM’s classic three-speed automatic-shift transmission, a foundational piece in the GM lineup known for its simplicity and dependability.

The TH400: The Big-Block Standard

Stepping up, the TH400 or THM400, stands as a heavier, bigger, and longer three-speed automatic transmission, designed for GM’s big-block automotive engines and renowned for its strength.

The 700R4: Advanced Overdrive Innovation

The 700R4 represents an evolutionary step as an upgraded 4-speed automatic-shift overdrive transmission, which was installed longitudinally in the vehicle chassis for improved performance, surpassing its predecessors like the TH350 and TH400.

The 4L60E: The Modern Era’s Answer

Finally, the 4L60E emerges as a modern marvel with its 4-speed automatic overdrive transmission and electronic control, setting a new standard that sets apart the latest GM vehicles with refined precision and adaptability.

Applications

TransmissionApplicationsCase MaterialLengthWeightFluid Type
TH350All Chevrolet and GMC pickups, trucks, and cars (1969-1986). Also suitable for vehicles grouped under other GM divisions.Single piece of cast aluminum alloy with an integrated bell housing21.75 inches120lbsDEXRON ATF or DEXRON III (H)
TH400327 V8 (Rambler/AMC, 1965-1967), 304 V8 (AMC, 1972-1979), 360 V8 (AMC, 1972-1979), 401 V8 (AMC, 1974-75), Rolls-Royce, GM, Jaguar, Ferrari etc.Cast aluminum alloy24.37 inches135 lbsDEXRON ATF or DEXRON III (H)
700R4Chevrolet Blazer/GMC Jimmy 1982-1992, Pontiac Firebird/Chevrolet Camaro 1983-2002, Chevrolet Corvette 1982-2005, Oldsmobile Customer Cruiser 1991-1992, Chevrolet Suburban 1984-2010, Chevrolet Van 1982-2012, etc.Die-cast aluminum23.4 inches155lbsDEXRON ATF or DEXRON III (H)
4L60EBuick Roadmaster 1994-1996, Buick Rainier 2004-2007, Chevrolet Corvette 1994-2004, Cadillac Escalade 1999-2000, 2002-2005, and many others.Three distinct pieces of cast aluminum alloy-the main case, bell housing, and tail housing21.9 inches155lbsDEXRON VI

Cost

TransmissionPart #YearsAuto-Shift Valve BodyDrivetrainPrice
TH3501130011965-1991Chevy Small Block and Big Block2-wheel drive$1,499.95
TH400112021965-1971Chevrolet Small Block and Big Block2-wheel drive$1,543.95
700R41171 011984-1991GM 700R4/4L602-wheel drive$2,371.95
4L60E1173081998-2006GM 4L60E for LS Engines2-wheel drive$2,709.95

Common Problems

GM’s automatic transmissions, from the TH350 to the 4L60E, each component—mechanical or electronic—is subject to the inevitable journey of natural wear and tear. Worn-out gears and aged assemblies speak to the lives these vehicles have lived. The TH350 may develop pump noises, often a chorus of intermittent whines signaling an inconsistent transmission fluid level or, worse, water contamination. Slippage, that hesitant dance between gears, often points to a defective vacuum modulator or a leaking oil filter—signs that it’s time to replace or rejuvenate to restore the condition of these storied workhorses.

TH350

Within the transmission community, the TH350 is known for its resilience, yet like any piece of intricate machinery, it has its quirks. Owners may note slippage during gear changes, a tell-tale sign of a defective vacuum modulator or a leaking oil filter. Mechanics’ forums often cite noises from the pump, which may occur intermittently and are typically attributed to an inconsistent fluid level or worse, water contamination. Sounds are the transmission’s way of crying out for attention—ignoring them is an invitation for more significant issues.

TH400

The TH400 is renowned for its durability in the GM family, but even this stalwart can face issues such as premature gear shifting which leads to compromised efficiency, often noticed with unwarranted engine revving. Improper fixing of the sealant can also result in ATF (automatic transmission fluid) seeping into places it shouldn’t, like the hose—a problem that speaks to the importance of meticulous maintenance. Drawing from my own technical background, I’ve learned that even the smallest oversight in the TH400 can undermine its legendary performance, illustrating the complex interplay of power and precision.

700R4

When it comes to the 700R4, a mainstay in the GM transmission series, certain ailments are common. A non functioning or inoperable governor often points to grimy transmission fluid, which can wreak havoc on internal regulation. Fractured or shattered input shafts are a clear distress signal, typically resulting from overheating—a byproduct of heavy-duty use or an engine’s high power output. As an experienced mechanic, I’ve seen how these issues can impede a 700R4’s performance, and they serve as critical reminders of the need for regular maintenance and the respect of operational limits.

4L60E

The 4L60E transmission, a stalwart in the GM lineup, isn’t immune to issues. Mechanics often troubleshoot faulty gearing—a misalignment of the transmission’s symphony. Discolored fluid can signal internal wear, while leaking is a telltale sign of seals giving way. A burning smell or damaged components within can give off odors that are a clear distress signal. And when the engine is running, a high-pitched or piercing noise during an attempt to shift gears may indicate a deeper malaise in the transmission’s heart. As someone who’s delved into the guts of these machines, these symptoms demand a swift response to avert a transmission’s cry from becoming a full-blown aria of dysfunction.

Conclusion

In the grand scheme of GM’s engineering marvels, the transmissions in question – TH350, TH400, 4L60E, and 700R4 – stand as pillars of performance and reliability. Reflecting on the journey from manual to advanced automatic systems, each transmission type offers a unique slice of automotive history. Whether it’s the TH350’s legacy in the daily commute, the TH400’s prowess on the drag strip, or the 4L60E and 700R4’s sophisticated electronic control and fuel efficiency, these components are the lifeblood of GM vehicles. They represent the robust build and power delivery needed for both open road exploration and high-octane performance, with a torque capacity to handle high-powered engines. The choice between them for a Chevrolet or Corvette is more than a matter of compatibility; it’s a decision steeped in a legacy of versatility and a commitment to innovation manufactured for excellence.

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