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August 2021

Overview of the 4L65E Transmission

4L65E Transmission - Gearstar

Gearstar – Overview of the 4L65E Transmission

The 4L65E transmission developed by General Motors for GM trucks – but adapted for the Chevrolet Corvette – is an updated version of the 4L60E. Both are automatic vehicle transmissions designed for rear-wheel-drive automobiles due to their longitudinal alignment. The 4L65E transmission was an off-shoot of the TH700R4 – ‘TH’ stands for ‘Turbo Hydramatic’– initially developed in 1982.

Even though it is a successor of the 700R4, the 4L65E transmission is an electronic automatic transmission, unlike its predecessors like the 4L60E. It comes with a 5-pinion gearset, overdrive, and a stock torque limit of up to 380 ft.-lbs. torque.

Brief History of the 4L65E Transmission

The 4L65E transmission has a history that dates back to the ’60s. At the time, General Motors launched the Turbo-Hydramatic 350 as a brand-new, highly improved automatic transmission and a worthy successor to the Powerglide.

Most GM trucks sport the TH350 as well as several rear-wheel-drive vehicles until the mid-1980s. The Turbo-Hydramatic 350 survived this long due to its sturdy build, compact size, and reliability.

Although the TH350 weighs 120 lbs. and is less than 22 inches in length, at the time, it was the transmission that packed enough punch to drive an SUV or Jeep. This transmission had no torque controller until an improved version – i.e., the TH350-C – was created.

However, General Motors eventually replaced the Turb-Hydramatic 350 transmission with the 700R4.

The 700R4 is recognized as the transmission that made the 4-speed automatic transmission incredibly popular in the market. It introduced a new feature – i.e., overdrive – for drivers in America who were somewhat more fuel-conscious I the 1980s and even beyond.

At the time, fuel prices were very high, and automobiles were still in great demand. The 700R4 transmission, which incorporated several features – such as power, durability, etc. – that made the TH350 excel in its days, allowed vehicles made by General Motors to ride smoothly and more efficiently.

The 700R4 is a non-electronic transmission that allows General Motors to meet strict emission guidelines via better fuel efficiency and access to overdrive. This helped GM customers to save a lot of money on fuel costs. Even now, the 700R4 transmission acts as a premium stock following aftermarket modifications, and this makes it easy to stick into big-block racing automobiles without electronic controls after modification.

The 4L60E eventually succeeded the 700R4 – which was once designated a 4L60 in the early 1990s – in 1997. It was GM’s #1 automatic overdrive transmission with electronic controls.

The 4L60E and 700R4 sport the same weight, length, as well as overall bellhousing. The primary difference between the two transmissions has to do with the introduction of electronic controls and an actuation system and adapted valve body to go with the new actuators and solenoids.

Throughout its lifetime, several versions of the 4L60E hit the market. And each version was only differentiated from the other via their tail housing as well as the lack – or presence – of removable bell housing. 

However, the 4L60E transmissions made after 1996 were not interchangeable and compatible with older models. This was due to a significant change in a 6-bolt tail shaft and solenoids.

Eventually, in 2001, a much stronger – and updated – version of the 4L60E transmission hit the market. This transmission was accompanied by a considerably improved input shaft and 5-pinion planetary carrier. 

The 4L65E transmission also sports a different torque controller as well as a hardened sun shell. Thanks to its planetary carrier, it also had better potential as a big block performance electronic transmission.

The 4L65E Transmission Specs

The 4L65E Transmission sports a 5-pinion planetary carrier, a 300mm input shaft, and a much better 3-4 clutch (compared to the 4L60E transmission). The following are the gear ratios of the 4L65E Transmission:

  • 1st gear: 3.06
  • 2nd gear: 1.62
  • 3rd gear: 1
  • 4th gear: 0.69

The upper limit for the 4L65E transmission is 700hp. Beyond this, it is advisable to swap this automatic transmission for a 4L85E, and the latter is much stronger but also more power-hungry and pricier.

Vehicles That Used the 4L65E transmission

Some vehicles notably featured the 4L65E transmission. Here they are in no particular order:

  • GMC Yukon Denali
  • Cadillac Escalade
  • 2005 C6 Corvette
  • Hummer H2
  • Cadillac Escalade EXT
  • 2002 Isuzu Axiom 
  • Holden One Toer 2004 Only
  • GMC Sierra Denali
  • Chevrolet Silverado SS
  • 2005-2006 Pontiac GTO (3.46:1 final drive, M32)
  • Holden Crewman 2004 Only

The 4L65E Transmission: What Sets It Apart from Other Transmissions?

It will take a little practice and mechanical know-how to easily differentiate or identify the 4L65E transmission from similar transmissions such as the 4L60E and the 4L60E/700R4. Even though the 4L65E transmission comes with a different sun shell and a much thicker input shaft, the only way to fully identify this automatic transmission is by opening it up.

Another way to pinpoint the 4L65E transmission requires in-depth knowledge of the alternate designations (M32 for the 4L60E transmission and M32 for the 4L65E transmission) – and some vital cosmetic differences – for the automatic transmissions. 

The older 4L60E transmission comes with a 4-bolt tail housing, which is different from the 4L65E transmission’s 6-bolt tail housing. Even so, the later 4L60E transmissions came with a removable bell housing as well as a 6-bolt tail housing. The performance versions of the 4L60E transmission are – on certain occasions – designate with M32.

In the end, the best way to fully identify the 4L65E transmission is to bring it to a reputable workshop. The transmission codes and designations and gauging the difference between input shafts will be checked and carried out, respectively.

However, the key differences between the 4L65E transmission and other automatic transmissions can only be visible within the transmission, i.e., when opened up.

Issues with the 4L65E transmission

Most drivers rarely have problems with the 4L65E transmission. The only major issue with this automatic transmission is the noticeably wide gear ratio between the first and second gears, i.e., 3.06:1 and 1.62:1, respectively.

This makes drivers experience a rougher transition at these speeds. However, modifying this transmission is possible, but only in some automobiles.


Some drivers say the 4L60E performs much better than the 4L65E transmission in some aspects. No one categorically says you can stick with only one transmission and stick with the other since choosing between these transmissions mostly depends on your budget.

You can jump to a 4L65E Transmission if you need that extra power that an additional pinion brings to the table. But if your vehicle is of a heavier build and requires more horsepower and torque, getting the 4L65E transmission would be a wise decision.

Overview of the 2004R Transmission

2004R Transmission - Gearstar

What ultimately makes the 2004R Transmission stand out among others is its sturdy construction, and this makes it an excellent choice.

When you see the 2004R Transmission today in salvage yards or many of its spare parts in auto part stores, it can be pretty difficult to recall that it was once the belle of the transmission universe.

Even though the 2004R Transmission was less known than the other popular General Motors overdrive transmission created in the 1980s, its popularity was undeniable. And it is now more than three decades since this exceptional Transmission was launched.

Besides, if you own a classic muscle car and want to upgrade its TH-350 3-speed or Powerglide 2-speed transmission, your best move would be to opt for the 2004R Transmission. This is not only because the latter is an excellent fit for the build but also the perfect Transmission to use if you want to upgrade your classic muscle car to improve your fuel economy and more punch.

The 2004R Transmission offers a lot of features, and that is what you will learn in the following paragraphs.

Introducing: The 2004R Transmission

The 2004R refers to the 4-speed automatic Transmission created by GM for the 1981 model year. It can be used efficiently in many General Motors passenger vehicles because it was fabricated with a Chevrolet and a B-O-P bell housing bolt structure. The automatic Transmission was produced with the Buick, Oldsmobile, and Pontiac patterns.

The 2004R automatic Transmission’s bell housing, driveshaft, and mechanical speedometer enable it to be an excellent fit for vintage automobiles. Besides, the 2004R Transmission’s torque capacity and sturdy build make it a much better – and advanced – non-electric overdrive transmission for classic vehicles for General Motors.

A Brief History

The 2004R Transmission was primarily designed as a continuation of the Turbo Hydramatic line of GM transmissions. This is an automatic overdrive that you will find in cars like the Buick Grand National and Pontiac Firebird Trans-Am, as well as in high-power GM trucks.

However, for some reasons highlighted much later on here, the production of the 2004R Transmission was suddenly discontinued in 1990. And a replacement, the 700R4 Transmission, came on the scene. The 4L60, as well as the 4L60-E, are iterations of the 700R4 Transmission.

The List of Vehicles Powered by the 2004R Transmission

General Motors used the 2004R automatic transmission to power several B-body, C-body, D-body, and G-body automobiles. 

Some of the vehicles that came with the 2004R include:

  • 1981-84 Buick Electra
  • 1981-89 Cadillac Fleetwood
  • 1981-90 Buick Estate Wagon
  • 1981-89 Chevrolet Caprice
  • 1982-83 Jaguar ZR W L6 220 3.6L S S
  • 1983-87 Buick Regal
  • 1983-89 Pontiac Parisienne, etc.

Differentiating the 2004R Transmission from Others

Differentiating the 2004R automatic Transmission from the 700R4, TH350, as well as other transmissions created by General Motors, is relatively easy.

To begin with, you can quickly locate the transmission identification of the 2004R on the plate positioned on the right side of the case, pointing towards the tail shaft. This plate bears a 2- or 3-letter transmission code printed in large alphabets. 

Another way to readily identify the 2004R automatic Transmission is by counting the number of pan bolts. If it is up to 16, it is either 2004R or 700R4. A bit confusing, that’s for sure. But the size of the 2004R’s pan bolts tends to be smaller towards its end. In contrast, the 700R4 Transmission’s pan bolts maintain a perfect square all through.

It is also relatively easy to confuse the 2004R Transmission with the TH350 because they feature similar dimensions. However, the 2004R has 16 bolts on its square transmission pan, while the TH350 has 13 bolts.

The 2004R Transmission: Specs

Here is the basic information/specifications of the 2004R automatic Transmission

  • Manufacturer: General Motors (GM)
  • Production Year: From 1981 to 1990
  • Overdrive: Yes
  • Computer-controlled: No. It is controlled by a lock-up torque converter and TV cable.
  • Outer Case Material: Aluminum, expertly fused with bell housing
  • Weight: 118 pounds when devoid of the ATF or torque converter
  • Type: 3-speed automatic
  • Fluid Capacity: 11 quarts
  • Speedometer Type: Mechanical
  • Torque Converter Lock: Yes
  • Pan Bolts: 13mm heads
  • First Gear Ratio: 2.74:1
  • Second Gear Ratio: 1.57:1
  • Third Gear Ratio: 1
  • Fourth Gear Ratio: 67.10.67:1 
  • Reverse Gear Ratio: 2.07:1
  • Case Length: 27 11/16 inches

2004R vs. 7004R vs. TH350 Transmissions

If you want to, you can compare the 2004R Transmission with the 700R4 and TH350, the two other overdrive transmissions created in the 1980s. 

First of all, the 2004R transmissions share remarkable similarities with the 700R4, despite being a much weaker variant of the 2004R/700 couplet. It must be mentioned that since the 2004R Transmission was created towards the end of the vibrant production year, it is still much better than the early 700R4.

It should also be pointed out that the 2004R Transmission was not deliberately designed to equilibrize or complement the 700R4 because they accomplish similar functionalities.

However, the 2004R Transmission fits quite well within the engine bays of existing ways in many ways that the 700R4 could not. But then again, the 700R4 shares the same bell housing bolt pattern and dimension as the TH350. And this singular factor made the transmissions interchangeable in automobiles exclusively designed for the TH350 Transmission in mind.

This implies that most classic vehicles initially made to use the TH350 3-speed Transmission can swap easily to the 2004R Transmission without the need for major or significant modifications. For example, there is zero need to reduce the original driveshaft.

The 2004R Transmission: Problems

No matter how perfect a transmission system is, it will still have a few drawbacks worth mentioning.

For instance, one of the problems associated with the 2004R Transmission is its inability to go into gear when needed. The 2004R Transmission gives cause for complaint by failing to go into gear despite the proper hooking up of the linkage.

Moreover, the Transmission may fail to respond as it undergoes a test in which you try to shift it through every gear, i.e., R/D/3/2/1. Nevertheless, you can check out the fluid level by using the dipstick to see whether or not there is enough fluid within the torque converter.

Another factor you need to bear in mind is that you need to make sure the pump transmits fluid and the shifter mechanism is in excellent working condition. When using the 2004R Transmission, slipping could occur, and this may cause it to give off a signal that your vehicle needs to undergo maintenance.

Slipping is commonly evident in delayed or slow acceleration, strange smells, or even hard shifting. Ensure the fluid level is not too low and that the valve moves forwards and backward smoothly without restraint.


As you can see, the 2004R Transmission may have been replaced with newer or more modern transmissions. Still, it was instrumental in its heydays, especially when installation space was a significant factor that couldn’t be joked with.

This transmission was a great fit in automobiles that formerly used the TH350 Transmission, and the need for major modifications was eliminated. Moreover, many vehicles used the 2004R Transmission, including Cadillac, Buick, and Chevrolet.

But what ultimately makes this Transmission stand out among others is its sturdy construction, and this makes it an excellent choice if you decide one day to upgrade your old-school muscle vehicle.

History of the 4L60E and How It Stacks Up Against the 4L80E

4L60E - Gearstar

The 4L60E is one of General Motors’ most versatile and durable 4-speed transmissions. So how does it stack up to it’s counterparts?

The 4L60E – whose components bear remarkable similarities with 4L65E automatics – is a series of automatics transmissions produced by General Motors. It is primarily designed for longitudinal engine configurations and includes four forward gears and one reverse gear.

Brief History of the 4L60E

The 4L60E is one of General Motors’ most versatile and durable 4-speed transmissions. It was formerly known as Turbo-Hydramatic 700R4 and is currently the electronic version that is popular today: 4L60E. General Motors manufactures the remarkable 4L60E in Romulus, Michigan, and Toledo, Ohio.

In 1982, General Motors initially conceptualized the 4L60 and 4L60E as the 4-speed overdrive automatic transmission known as TH700R4. At the time, the multinational corporation was urgently looking for several fuel-efficient methods to power its vehicles. This was right after the unfortunate ’70s fuel shortages that resulted in the massive influx of Japanese to North America. 

A recession in the early ’80s and rapidly-increasing fuel costs right at the pump had a massive and disastrous impact on auto sales. Since the -speed TH700R4 was much more efficient, it quickly replaced its three-speed counterpart, TH350. 

At the time, the Turbo 700 had a lower 3.06-to-1 final gear ratio – along with a 30 percent overdrive – that provided quick acceleration from a dead stop. However, the early versions of the TH700R4 went through growing pains as General Motors continued to kick out bugs for improvement. The multinational automaker was recklessly determined to make a resounding success of the four-speed TH700R4. 

The Arrival of the 4L60 and 4L60E

In 1990, the automaker conveniently renamed the TH700R4 as the 4L60 to fully manifest its primary purpose as a 4-speed automatic with a longitudinally-placed matching engine and an overall vehicle weight rating of approximately 6,000 lbs. Note that the ‘4’ in both names represents ‘four gears’ while the ‘L’ stands for ‘oriented longitudinally.’

However, General Motors did not make any mechanical changes whatsoever to the TH700R4. And by 1997, this electronically-controlled shift version became much more available in 2- and 4-wheel drive trucks as well as rear-wheel-drive cars. Even the 6th generation Chevrolet Corvette was also fitted out with the 4L60E transmission. 

The 4L60E used electronic actuators and solenoids to control the valve body, clutches, and bands to shift gears. General Motors’ Vehicle Speed Sensor and a vehicle powertrain computer always determined precisely when gear shifting was optimum.

The 4L60E has different gear ratios:

  • 3.05-to-1 for first
  • 1.625-to-1 for second
  • 1.00-to-1 for third
  • 0.696-to-1 for fourth 
  • The 2.29-to-1 ratio for the reverse

How 4L60E Stacks Up Against the 4L80E

The automaker built the 4L60E as well as 4L80E, both of which are automotive transmissions. As stated earlier in this post, the 4L60E is the standard transmission used in many rear-wheel automobiles manufactured after 1993.

However, the 4L80E is generally limited to big block and diesel vehicles. It must be mentioned that these two automotive transmissions differ significantly in performance, origin, appearance, gear ratios, price, weight, size, etc. And, of course, the 4L80E automotive transmission is much more powerful than its counterpart, the 4L60E.

The 4L60E and 4L80E performance transmissions have similarities, such as being manufactured by General Motors and have a 4-speed automatic overdrive, respectively. This is where the considerable similarities between the two performance transmission models end.

Let’s take a look at the factors that stack 4L60E up against the 4L80E:

The Origin

Although the 4L60E and 4L80E share similar model numbers, there are marked differences between the two automotive transmissions. They are so different from each other, even right down to precisely how they are manufactured respectively. 

The 4L80E is an electronic overdrive successor of the Turbo 400 and is an earlier transmission model greatly favored by hot rod enthusiasts and drag racers.

On the other hand, the 4L60E automotive transmission is electronic transmission-based right off the 700-R4. This was fundamentally the standard transmission for GMC and Chevrolet vehicles right from 1982. 

The Appearance

The 4L80E automotive transmission is much larger than its counterpart, the 4L60E. It has an oval-shaped pan, while the 4L60E automotive transmission comes with a rectangular pan.

Moreover, the 4L80E transmission also requires many bolts – more than is necessary for the 4L60E automotive transmission – to secure it to the engine. This corresponds with more outstanding durability and a bigger size. 

There is also a gasket of up to 17 bolts on the 4L80E transmission unit, while the 4L60E unit has only 16 bolts.

The ’80’ in 4L80E implies that the transmission unit can support up to 8,000lbs. Of GVWR while the ’60’ in 4L60E means that this automotive transmission unit can handle up to 6,000 GVW. The ‘E’ in both models stands for ‘electronically’ controlled transmissions.

The Power

The 4L80E is undoubtedly the more powerful of the two automotive transmissions. High-speed automobiles for racing or big trucks used for towing vehicles or cargo generally require a 4L80E automotive transmission instead of the 4L60E. 

This is because the engine’s power is much more likely to break less powerful and smaller transmissions. But then, the 4L60E automotive transmission is powerful enough to work with the engines of most stock automobiles. 

The Size and Weight

The size and weight of both automotive transmission units are vastly different. The 4L80E is heavier – up to 236 pounds – and larger – with a length of 26.4 inches – than its counterpart, the 4L60E. 

However, the 4L60E weighs a mere 150 pounds – without any fluid – and has a length of 23.5 inches.

The amount of fluid these automotive transmission units will support depends primarily on the torque converter utilized in the transmission.

The Price

The 4L80E automotive transmission is much more expensive than its counterpart. The 4L80E is more powerful, larger, specifically manufactured, and designed for engines with significant horsepower. 

This 4L80E automotive transmission is a much better investment for high-speed vehicles and heavy-duty trucks with big engines. The 4L60E is much more susceptible to breaking, especially when installed on high horsepower engines.


The differences in the performances of the 4L60E and 4L80E automotive transmission units are numerous. And they show that the latter – i.e., the 4L80E transmission unit – is the better of the two.

However, it will cost you much more money to acquire the 4L80E transmission unit and is also relatively easier to find.

Therefore, if your vehicle demands applications that wear down the transmission, you may have to go for the 4L80E unit. But suppose you love driving at high speeds. In that case, the 4L60E automotive transmission unit is the best option since you will use a stock transmission that can significantly handle your vehicle’s engine power.


Overview of the 4R70w Transmission

4R70W Transmission - Gearstar

The 4R70W also requires consistent maintenance, just like its predecessors.This way, you will have an incredibly powerful transmission.

The 4R70W, a Ford transmission, is an evolution to the popular AODE and is often used interchangeably. Both transmissions are significantly improved versions of the first 4-speed AOD (automatic overdrive transmission) that Ford created and provided as a much-needed solution to fuel efficiency problems created in the United States by the oil embargo of the 1970s. Chrysler and General Motors followed swiftly with their respective versions.

And since then, several regulations and rules to considerably improve the quality of air and fuel efficiency have been published. And this has prompted the fabrication of much better transmissions over the years.

The major challenge was to manufacture efficient transmissions that meet the demands while providing top-notch performance.

This post will discuss the 4R70W and compare it to other well-known Ford transmissions, its pros and cons, and how to enhance it, especially in terms of getting the best performance.

Brief History of the Ford 4R70W Transmission

Car manufacturers began to wise up in the ‘70s and started manufacturing fuel-efficient vehicles. And for this to happen successfully, the manufacturers had to sacrifice a handful of the speed and performance features that older models exhibited. However, fuel-efficient automobiles were environmentally and economically friendly and could cover more miles with far less fuel.

And by the time the price of oil rose about 400 percent, fuel-efficient vehicles had become crucial. By 1980, Ford created the 4-speed automatic overdrive transmission (AOD).

Although the automatic overdrive transmission was relatively new, it still bore several features of old designs. The AOD efficiently replaced several older transmissions that Ford put out, including the C4, C5, and FMX. It wasn’t all that different from the FMX 3-speed automatics since common FMX components – such as the Ravigneaux gear train, etc. – were also part of its components.

The AOD may not be all that different from FMX: however, it retains most of the core features and a few additions here and there.

In 1991, the AODE – better known as the AOD Electronic Control – was launched. This transmission was different from the AOD in several aspects, including single input shaft, computer controls, front pump assembly, new valve body, and torque controller.

Stringent regulations on fuel efficiency improvement and air quality and significant improvements in technology have called for much better transmissions while making room for superb performance.

The truth is there is no perfect stock transmission. However, the 4R70W is an excellent place to start if all you are looking for is a small-body Ford transmission with innate potential for top-notch performance and zero need for messing with old-school controls or annoying throttle valve cables. But then, the 4R70W is also not a great place to end your search either.

The 4R70W Transmission Specs

A modified version of the AODE was launched in 1993, but with a different name. Nevertheless, both transmissions are interchangeable. The 4R70W arrived at the scene with the following specs:

  • 4 forward speeds
  • Rear-wheel drive
  • Wide gear ratio
  • 700 newton-meters torque rating

The gear ratios of the 4R70W transmission are:

  • First gear: 2.84
  • Second gear: 1.55
  • Third gear: 1:1
  • Fourth gear: 0.70

The respective gear ratios of the AOD are:

  • 1st gear: 2.40
  • 2nd gear: 1.47
  • 3rd gear: 1:2
  • 4th gear: 0.67

You can see the difference in gear ratios when you compare them side by side. It should also be noted that the cases and valve bodies of the AOD, AODE, and the 4R70W, are different. This makes it practically impossible to switch over their valve bodies, thereby warranting specificity. 

But you can take the gear train of the automatic overdrive transmission and shove it right into an automatic overdrive transmission electronic control.

Which is Better: the AOD or 4R70W?

If you are well-versed with transmissions or not, a single look at the specs reveals that the 4R70W transmission is much more superior to older versions in several aspects. But this is not to imply that it will remain the best option at all times.

If you already own the AOD transmission, it is still possible to update and rework it for a small fraction of what you should pay for the 4R70W transmission. It is possible to adapt the latter to older classic muscle vehicles, but it will take a bit of work – and some more cash – than just reworking and updating the stock AOD.

The same thing applies to automobiles with the AOD Electronic Controls in the 1990s. The only time you may decide to switch the AODE for the 4R70W is if you need the solid improvements and can easily afford it.

Pros and Cons of the 4R70W Transmission

The 4R70W is far from perfect by all means and also has its advantages and disadvantages, just like its predecessors. Here are some of the excellent qualities of this remarkable transmission, as well as a few shortcomings you should be aware of:


The most significant benefit that the 4R70W transmission brings to the table is its considerably improved overdrive band, a pretty solid input shaft, better front pump, and improved pinpoint precision control.

Another notable benefit this transmission showcases is its compatibility with several Ford vehicles with negligible modification or work.

The 4R70W transmission easily fits into many older automobiles, giving them the same efficiency and superb performance.


Overloading the 4R70W transmission is a bad idea. And that is why you should know what it can – and what it can’t – do. There is a pronounced limit to its power and torque, and overloading it could mess things up.

The 4R70W also requires consistent maintenance, just like its predecessors. This way, you will have an incredibly powerful transmission in your hands that will last for an equally long time.


As mentioned earlier, no stock transmission is perfect in every aspect. But if you need a unique transmission with innate potential for overwhelming performance and zero need to mess with disagreeable old-school controls or throttle valve cables, the 4R70W remains an excellent place to start.

Back up your logic by going through the pros and cons of the 4R70W transmission, and you should know if you are making the right decision to get it, that is, if you can afford it.