The General Motors (GM) 700r4 transmission, also referred to as the “Turbo Hydra-Matic”, surfaced in 1982 to replace the retired, less durable, 3 speed TH350. The transmission was met with praise in the automotive markets. There was a growing demand for more fuel efficiency and less emissions, and the 700-R4 met the challenge. Fuel consumption decreased by as much as 30% on the highway.
Replacement parts for the 700-R4 were easily accessible in addition to perks like the impressive improvement to fuel economy and cooler operating temperatures. The 700-R4 was one of the best automatic transmission designs in its class and paved the way for more innovative designs as technology evolved.
Identification
The identification of a 700-R4 is easily identifiable due to special features. The main cast is made of cast aluminum alloy with three main castings. One distinctive feature is the identification tag on the rear passenger side of the unit. The first number on identification tag is the year the model was made, followed by the model of the unit, and plant of manufacture. Identify the 700-R4 by locating the TV cable used to control line pressure and shift points.
The two wheel drive models will have a tail housing and the output shaft is longer. The 4 wheel drive output shaft on the 700-R4 stuck out for about 3 inches, which is about 2 inches longer than the shaft in the TH350. To identify the 700-R4, you should also look for the 16 bolts around the transfer case. Another primary distinction between the 700-R4 and the 4L60 is the rear output with four bolts. As mentioned, the three wheel drive model has shorter output shafts and adapter assemblies. One last distinction, the electronic version of the 700-R4 will not have a worm drive.
700R4 Specifications and Ratios
The 700-R4 was made manufactured with cast aluminum and measures about 23.4 inches long. The transmission weighs about 155 lbs with around 16 bolts and offered a standard V8 90° metric bolt pattern with 4.3 V6. The 700-R4 is compatible with V8 and AMC 16 engines:
| 700R4 Transmission Specs | |
| Type | 4 speed, overdrive automatic transmission |
| Applications | 1982 – 2012 GMC, Buick, Chevrolet applications |
| Case Material | Cast aluminum |
| Case Length | 23.375” overall |
| Input Spline | 27 spline from 1984; 1984 on 30 spline |
| Weight | ~ 200 lbs dry |
| Fluid Type | DEXTRON VI, 8.8 to 11.4 quart capacity |
| Tail Shaft Housing | 625 inches |
| Max Gearbox Torque | 650 lb/ft |
| Max Eng Torque | 350 lb/ft |
| Identification |  |
The 700-R4 lower first gear ratio is a source of superior performance for low speed. The 30% overdrive is the source of popular fuel economy. The first gear ratio of 3.06 was lower than normal, and provided off road torque and offline acceleration:
| 700R4 Transmission Ratios | ||||
| 1st | 2nd | 3rd | 4th | Reverse |
| 3.059:1 | 1.625:1 | 1.00:1 | 0.696: 1 | 2.294:1 |
History
The birth of the 700-R4 changed the market for automatic transmissions. The TH350 transmission was less durable and lacked an overdrive gear. The replacement 700r4 was a 4-speed automatic transmission was a bit longer in design, fully equipped with the overhead gear. The model featured a lock-up torque convertor (view on Amazon) that allowed a connection which was direct and non-slip. A TV cable was used as a throttle position sensor for gear shifting. A new model of forward clutch was being manufactured by May 1982, which replaced the roller clutch found on all THM 700r4 transmissions. The longitudinal 700-R4 became an upgrade for many of the older, rear-wheel drive cars.
The change affected several aspects of the transmission:
1. Inner Race – A pressed on flange was added
2. Outer Race – The lube hole positions were changed along with the inside diameter
3. Roller clutch assembly – The assembly was changed to Sprag freewheel with 26 elements
4. Input Sun Gear – The sun gear shoulder was reduced, reduced overall height
5. Overrun Clutch Hub – A raised area was added to tangs on hub
Some of these changes are discussed in more detail in the next section.
Important Changes
The 700-R4 was used in automobiles between the periods of 1982 – 1993. Many trucks and rear wheel drive automobiles such as the Corvette, Camaro, Jimmy, Suburban, 1/2 ton pickups, S15 and S10 trucks benefitted from a better transmission. Until 1993, the 700-R4 was revised many times. Some of the changes to the engineering design significantly influenced how the current 700-R4 transmission has evolved. The following are only a few of the changes made to the 700-R4 up to 1993:
1982
A new forward sprag clutch was being produced to replace the 700-R4 forward roller clutch. The roller clutch assembly and input sun gear were affected by the change.
1984
In January of 1984, the 700-R4 transmission was designed with Reaction Internal Ring Gear which did not cause any dimensional changes. The Reaction Internal Ring Gear was added to prevent the ring gear from breaking and to increase overall durability. The part affected was the rear internal ring gear.
In June of 1984, the 700-R4s were designed with new Pump Body and Pump Cover Assemblies with oil dams. The Pump assemblies were added to reduce the number of oil pump fluid leaks. Parts affected were the oil pump body and the oil pump cover.
The 700-R4 upgraded from a 27 spline input shaft to a 30 spline to address the common failure point.
1985
In March 1985, the 700-R4 transmission was manufactured with a new oil pump assembly with inner and outer slide springs. The part affected was the oil pump assembly.
At the start of production in 1985, the 700-R4 received a new Reaction Carrier with ‘Bat Wing’ thrust washers beside the pinion gears. Some models also received oil deflectors. The change was made to improve the rate of wear and tear on the pinion gear thrust washer, improve pinion gear needle bearing lubrication, and improved durability. The part affected was the Reaction Carrier itself.
1986
In June 1986, the 700-R4 received an upgrade of the Lower Roller Clutch Assembly with rollers that were about .150 inches longer. The change was made to increase the torque carrying capacity. The change also meant a new design case had to be produced. The parts affected by the change were the Lower Roller Clutch Assembly itself and the Lower Roller Clutch Support Assembly.
Another change in June 1986, the 700-R4 were given a redesigned 1-2, 3-4, and forward clutch accumulator pistons with soft rubber seal to replace the Teflon used in prior models. The change was made to improve the sealing capability in the accumulator bores. The parts affected by the change were the 1-2 Accumulator Spring, the Accumulator Pistons, and the Accumulator Piston Seals.
In July of 1986, the electronic speed sensor was introduced to procure highly accurate speed sensor signals for anti-skid braking. The parts that were affected by the change were the Speed Sensor, Output Shaft, and Transmission Case.
1987
In February 1987, a reverse apply package was introduced which changed the Low/Reverse Clutch Pack and the Reverse Input Housing.
In July 1987, the 700-R4 received a new overrun clutch hub with more drilled holes. The change was made to significantly improve the overrun clutch plate lubrication. The part affected by the change was the Overrun Clutch Hub itself.
Another change the 700-R4 received in 1987 was a revised Forward Sprag Assembly with sprag elements increased. The change was made to significantly improve the torque carrying capacity to improve durability. The parts affected by the change were the Forward Sprag Assembly itself, the Input Carrier Thrust Washer, the Forward Sprag Inner and Outer Races, the Forward Sprag End Bearings, and Forward Sprag Wear Plate.
1988
In July 1988, the 700-R4 received an upgraded valve body assembly with new 1-2 shift valve lineup and 3-4 throttle valve. The change was made to improve the consistency for 1-2 and 3-4 upshifts and braking at higher speeds during manual downshift. The change affected the 1-2 Shift Valve Line Up, 3-4 Throttle Valve, Number 9 Checkball, and the Spacer Plate and Gaskets.
1990
In 1990, GM coded and renamed all of their transmissions. GM renamed the 700-R4 to a 4L60 suitable for vehicles weighing around 6,000 lbs. The model was still the same as the 700-R4 had been in many ways until more significant changes came in 1993.
1993
In January 1993, all 700-R4 model transmissions were manufactured with a new reverse input housing with square feed hole to replace the .095” round hole. The change affected many aspects of the transmission, especially to the valve body. The hydraulic shifting system in the 4L60 was replaced by electronic controls with a Vehicle Speed Sensor.
700-R4 Design and Operation Issues
The 700-R4 design was not without complication. Despite the awesome design, the 700-R4 has been associated with overheating problems. The overheating has a negative effect on the internal parts under the hood. To remedy the problem, an auxiliary transmission cooler is installed.
Premature reverse input clutch failure was another problem in models between 1987 and 1993 with aluminum reverse input clutch. The problem was believed to be caused by an orifice that was too large in the Feed-Bleed system. One solution was to install a .062 inch orifice cup plug into the rear of the piston.
Another issue with 700-R4 is a broken input shaft. The unit did not respond well to excessive torque, and often times the shaft has broken. To remedy the problem, the number of spline in the shaft was increased.
A stuck governor (view on Amazon) has also been a recurring theme in the 700-R4. This issue was mostly caused by dirty transmission fluid that affected the springs. To remedy the problem, the vehicles were serviced more often.
There have been complaints as to why sometimes the torque converter slips or won’t lock. This occurs because of the converter inside the 700R4. This may be remedied by replacing the transmission fluid and flushing.
Redesign as 4L60
The 700-R4 was redesigned as the 4L60 in 1990, and then the 4L60-E. However, many of the most important transmission upgrades were performed by 1987. The 4L60 was also longitudinal, with 4 speed and 6,000 lbs GVW. The major differentiation between the 700-R4 and the 4L60 did not really occur until 1993, when the hydraulic logic shifting system was replaced by an electronic one. This meant that many parts, such as the actuation system, valve body were controlled electronically. The Vehicle Speed Sensor was designed as the feedback sensor.
Today, there is considerable aftermarket support for the 700-R4. The TH350 (view on Amazon) and the 700-R4 (view on Amazon) transmissions are still available in many markets, as well as its parts. Many enthusiasts enjoy working with the 700-R4 due to the pioneering benefits of its design.