General Motors Company set the ball rolling for modern-day automatic transmission for its automotive gasoline engines by introducing the 1940 Oldsmobile. GMC pioneered the basic technology involving automatic transmission by embedding the original Hydramatic or Hydra-Matic transmission in the Oldsmobile launched in 1940. Though automatic transmission technology has hugely evolved since it was introduced about eighty years ago, the core design remains nearly the same.
This article will compare and contrast four distinct GMC transmissions-TH350, TH400, 4L60E, and 700R4 based on standard performance specs.
Table of Contents
GM TH350 (or ‘Turbo 350’)
The GMC Turbo Hydra-Matic 350, famous as “Turbo 350,” first appeared in 1969 to replace the GM’s two-speed Powerglide transmission.
GM’s Buick and Chevrolet divisions designed the THM350 primarily for its Chevrolet trucks and cars (1969-1986), having small-block engines.
The TH350 is a 3-speed transmission with a higher 1st gear ratio (2.52:1) and a provisional 2nd gear, facilitating enhanced initial momentum for drag racing and everyday driving.
GM developed and promoted the three-speed automatic-shift transmission to replace the standardized two-speed transmission-Powerglide. General Motors accomplished a high level of perfection in automatic transmission with the TH350. The GM THM350 became so popular that the transmission paved the way for launching a series of sophisticated automatic transmissions in due course.
The THM350 is often called CBC 350 as GM’s Buick and Chevrolet divisions joined hands to develop the TH350. Almost all GM cars and trucks (rear-wheel-drive) produced from 1969 till 1984 carried the THM350. The THM350 found widespread application, especially in small-block V8 and V6 engines owing to the transmission’s solidness, versatility, and power.
GM TH400 (or ‘Turbo 400’)
The TH400 was the foremost amongst General Motors’ three-speed transmissions that debuted in 1964, appearing under the hood of Cadillac.
General Motors released the THM400 automatic transmission mainly to replace the standard ST300 2-speed automatic transmission. The THM400 transmission became the default transmission of Oldsmobile, Chevrolet, Ferrari, and Jaguar cars within a year of its launch.
Thanks to its robust build and reliability, this automatic transmission later found its way into Camaro, Corvette, and Chevelle engines.
General Motors brought out the TH400 transmission earlier than the automatic transmission models like TH350, 700R4, and 4L60E. The TH400 transmission speaking is a three-speed, automatic-shift longitudinally set transmission constructed durably for long-term use. The longitudinal placement of the GM TH400 automatic transmission ensures an excellent power ratio and smooth and durable rear-wheel drive.
The GM 4L60E is the electronic version of the 4L60, which was introduced as 700R4 in 1982. General Motors wanted to do away with lightweight 3-speed transmissions and introduce a fuel-efficient 4-speed automatic transmission. And that is how the 700R4 saw the light of the day and was later rechristened as 4L60.
The “4” in 4L60 indicates the total number of forwarding gears, “L” stands for longitudinal mounting, and “60” signifies torque capability.
The 4L60 transmission with the suffix ‘E’ first emerged in 1993 to distinguish it from its earlier hydraulic version. 4L60’s electronic variant came with an automatic powertrain control module, unlike the mechanically-operated hydraulic transmission.
This electronic transmission also featured a digital speed sensor for conveying information to the vehicle’s speedometer. The Chevy featuring a small-block engine and a bolt-on bell housing, came equipped with the initial 4L60E transmission.
The 4L60E Transmissions from GM are automatic 4-speed overdrive longitudinal mounted transmissions featuring five gears, four forward, and one reverse. The General Motors 4L60E transmission has a 425lb/ft torque with a horsepower rating of up to 450 HP. This robust 4-speed automatic transmission is presently regarded as the most versatile and powerful overdrive transmission ever made.
A relentless endeavor by General Motors to improve the design of existing automatic transmissions led to the 4L60E’s emergence. The 4L60E is the computerized or digital version of TH700R4 released in 1982 that became 4L60E in 1990.
GM 700R4 (or TH700R4)
Launched in 1982 to replace the THM350, the 700R4 wholly phased out the former transmission by 1984.
The GM Turbo Hydra-Matic 700R4 featured a vastly upgraded and advanced architecture than the TH350 with better fuel efficiency.
The 700R4 also had a higher 1st gear ratio than its predecessor (3.06 against 2.52), which improved acceleration.
GM produced dual variants or versions of 700R4 – the earlier editions came with a 27-splint shaft. The latter 700R4 variant had a more giant input shaft with 30 splints.
General Motors made concerted efforts to boost their automotive engines’ fuel efficiency and produced the 700R4 transmission. The GM TH700R4 is a longitudinally placed four-speed automatic-shift overdrive transmission installed inside Chevrolet and GMC trucks and cars. If you have an older Chevy or GMC pickup model, you can replace the worn-out THM350 with a 700R4.
4L60E vs. 700R4 vs. Turbo 350 vs. Turbo 400 Comparison Chart
|Identification||13 bolts||13 bolts||16 bolts||16 bolts|
|Ratios||1st: 2.52 : 1|
2nd: 1.52 : 1
3rd: 1.00 : 1
Reverse: 2.07 : 1
|1st: 2.48 : 1|
2nd: 1.48 : 1
3rd: 1.00 : 1
Reverse: 2.07 : 1
|1st: 3.059 : 1|
2nd: 1.625 : 1
3rd: 1.00 : 1
4th: 0.696 : 1
Reverse: 2.294 : 1
|1st: 3.059 : 1
2nd: 1.625 : 1
3rd: 1.00 : 1
4th: 0.696 : 1
Reverse: 2.294 : 1
|Types||3 speed automatic transmission||3 speed automatic transmission||4 speed automatic overdrive transmission||4 speed, overdrive automatic transmission|
|Applications||1969 - 1986 GMC, Chevrolet cars and trucks |
(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|
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 Material||Aluminum, 1 piece case casting with integral bellhousing||Aluminum||Die cast aluminum||Cast aluminum|
|Case to ext. Housing||21.75"||24 3/8"||23.375"||23.375"|
|Overall Length||Short tail: 27 5/8"|
Long tail: 30 5/8"
|Short tail: 28 1/4"|
Long tail: 34"
|30 3/4"||30 3/4"|
|Bellhousing to mount||Short tail: 20 3/8"|
Long tail: 20 3/8"
|Short tail: 26 3/4"|
Long tail: 28"
|22 3/8"||22 3/8"|
|Weight||~ 120 lbs||~ 150 lbs w/ ATF||~200 lbs dry||~ 200 lbs dry|
|Fluid Type||DEXRON ATF||DEXRON automatic transmission fluid||ACDelco DEXRON VI automatic transmission fluid||DEXRON VI|
Download the full comparison chart here
4L60E vs. 700R4 vs. Turbo 350 vs. Turbo 400: Differences Explained
Perhaps the easiest way to discern a GM Turbo 350 (TH350/THM350) is to look for the auto transmission’s vacuum modulator valve. You’ll find the TH350’s vacuum modulator ensconced at the main casing’s rear end. Another remarkable way to make out this transmission is by its square-shaped oil pan with a chamfered corner on the passenger side.
Unlike the GM’s Turbo 350, the Turbo 400 (THM400/TH400) vacuum modulator valve comes built-in on the casing’s passenger side. Also, the THM400 employs a mechanical (cable) kick-down system, whereas the THM has an electrically powered sliding switch.
A failsafe way to differentiate the early version of THM700R4 is through its four-bolt rear output.
You can tell a latter 4L60E from its earlier models (and all other GM transmissions) by its six-bolt hex rear output.
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The chief purpose of the gear ratio is to strike the perfect balance between torque & speed. Initially, when moving your vehicle from a resting position, you require more torque than power. Alternatively, you’d need more accelerating power than torque when cruising on the highway.
Simply put, the gear ratio is a trade-off between speed and torque.
The transmission or gear ratios for the first, second, third, and reverse gears of TH350 are 2.52, 1.52, 1.0, and 2.07. Level I, II, and III of Turbo Hydramatic 350 allow you to manipulate up to 400 pounds (lbs) of torque. On the other hand, the three gears and the reverse gear offer you a heft of up to 700 horsepower.
The GM TH400’s gear ratios are 2.48:1, 1.48:1, 1.00:1, and 2.07:1 for the 1st, 2nd, 3rd, and 4th gears. The THM400’s transmission works excellently for high-performance and heavy-duty vehicles. This General Motor’s transmission model designed for positioning longitudinally behind the vehicle’s engine furnishes good durability and optimal power ratio for rear-wheel drive.
The 1st, 2nd, 3rd, and 4th gear ratios of THM700R4 are 3.06:1, 1.63:1, 1:1, and 0.7:1, respectively. The ratio for the reverse gear is 2.9:1. The three gears and the reverse (30% overdrive) enable driving at controllable speeds without sacrificing fuel economy.
The 4L60E is a four-speed automatic transmission with gear ratios of 3.06:1, 1.62:1, 1.00:1, and 0.70:1 (for gears 1-4). So the 3 + 1 30% overdrive gears come in handy for pairing with both sports cars and passenger vehicles.
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What Type Is Each Transmission?
The GM TH350 transmission is a three-speed automatic-shift transmission.
The THM400 is also a three-speed automatic transmission, just like the TH350 but is heavier, bigger, and longer. Additionally, the TH400 was designed especially for big-block GM automotive engines, whereas the TH350 suited smaller block engines.
The 700R4 is an improved and upgraded model compared to its predecessors-TH350 and TH400. The GM THM700R4 is a 4-speed automatic-shift overdrive transmission installed longitudinally (front to back) over vehicle chasses. The 700R4’s performance is comparable to the GM 200-4R but sports a lengthier transmission.
The 4L60E features the same 4-speed automatic overdrive transmission design as 700R4, but it’s the former’s electronic control that sets the 4L60E apart.
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TH350 – All Chevrolet and GMC pickups, trucks, and cars (1969-1986). Also suitable for vehicles grouped under other GM divisions.
TH400 – 327 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.
700R4 – Chevrolet 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.
4L60E – Buick Roadmaster 1994-1996, Buick Rainier 2004-2007, Chevrolet Corvette 1994-2004, Cadillac Escalade 1999-2000, 2002-2005, and many others.
TH350 – Casing of body constructed from a single piece of cast aluminum alloy with an integrated bell housing.
TH400 – Body casing made from cast aluminum alloy
700R4 – The central case has been shaped out of die-cast aluminum
4L60E – The outer covering comprises three distinct pieces of the cast aluminum alloy-the main case, bell housing, and tail housing.
TH350 –21.75 inches
TH400 –24.37 inches
700R4 –23.4 inches
4L60E –21.9 inches
TH400 –135 lbs
Fluid Type (ATF or Automatic Transmission Fluid Needs)
TH350 – DEXRON ATF or DEXRON III (H)
TH400 – DEXRON ATF or DEXRON III (H)
700R4 – DEXRON ATF or DEXRON III (H)
4L60E – DEXRON VI
Talking about ATFs used in automatic transmissions, automatic transmission fluids have hugely evolved and come a long way. The majority of automatic transmissions made by different vehicle manufacturers used Ford (Type F) fluid or GM’s DEXRON. But things in the ATF world have changed drastically and for good. Even the latter-day and state-of-the-art ATFs such as DEXRON VI and DEXRON HP do not have universal applications.
If you own an older GM vehicle model (having a TH400 or TH350), sticking to the Type F (Ford) fluid is recommended. Employing Ford Type F helps boost the firmness of shift when you change gears. On the other hand, if you have a latter GM vehicle with a 4L60E or 4L80E transmission, then only use DEXRON HP or DEXRON VI.
TH350 – $1,4995.95 (1965-1991 Chevy Small Block and Big Block 2-Wheel Drive, Auto-Shift Valve Body Part # 113001)
TH400 – $1, 543.95 (Chevrolet Small Block and Big Block 2-Wheel Drive, Auto-Shift Valve Body 1965-1971 Part # 11202)
700R4 – $2, 371.95 (1984-1991 GM 700R4/4L60 2-Wheel Drive Auto-Shift Valve Body, Part # 117101)
4L60E – $2709.95 (1998-2006 GM 4L60E for LS Engines, 2-Wheel Drive, Auto-Shift Valve Body)
Please note that prices could vary depending upon the part number and from one site to another.
Like any other mechanical (or electronic) component in your vehicle, the automatic transmission is subject to natural wear and tear. Some telltale signs indicate that you’d need to replace your worn-out or old transmission.
It would help if you learned to recognize these signs sooner than later to keep your vehicle in running condition:-
- Transmission pump producing noises intermittently due to inconsistent transmission fluid level or water contamination
- Slippage of the transmission owing to defective vacuum modulator or a leaking oil filter
1. Premature gear shifting (and consequently compromised efficiency) caused by engine revving.
2. Improper fixing of sealant could lead to ATF or automatic transmission fluid seeping steadily into the hose.
1. Nonfunctioning or inoperable governor (owing to grimy transmission fluid)
2. Fractured or shattered input shaft
3. Overheating arising from heavy-duty use and high power output
- Faulty gearing
- Discolored fluid
- Leaking transmission fluid
- The burning smell of damaged transmission
- High-pitched or piercing noise emanating from the engine when you try to shift gears
For most GM vehicle owners, the OEM transmission plays a crucial role in influencing the vehicle’s overall performance. There’ll come a time when you’ll have to consider replacing the manual or automatic transmission in your car. In this article, we’ve studiously reviewed four GM transmission models-TH350, TH400, 700R4, and 4L60E.
If you own an older model of Corvette or Chevrolet, then go for a TH350 or TH400. On the other hand, if you drive a GM vehicle manufactured in 1982 or later, choose the 700R4 or 4L60E.