was successfully added to your cart.




Horsepower and Torque: The Difference

Horsepower and torque: The difference

A vehicle’s two top performance metrics bandied about by car enthusiasts are horsepower and torque. You will find them peppered all over every vehicle’s spec sheet, animated and bolded in every comparison video online, and plastered several times in reviews. But only a handful of individuals truly know the meaning of each metric and the significant differences between them.

Knowing what horsepower and torque stand for is highly essential, whether you’re buying a brand-new or used car. Not understanding the differences between these two metrics can result in poor decision-making when you want to buy your next vehicle.

Horse and torque are part of the metrics that indicate how a car engine or transmission will perform. This alone shows that you shouldn’t take these metrics at face value. Therefore, analyzing them is highly crucial. This is where brushing up on the basics becomes essential.

What is Horsepower?

Horsepower is a unit measurement of power, defined as the rate via which a vehicle engine performs work – as generated by torque. In simple language, horsepower is an excellent indicator of a car’s speed. 

A vehicle’s horsepower depends on its rotations per minute (RPM) and torque. In many cases, your vehicle’s engine won’t be pushed until it accomplishes peak performance. This is why it is very rare for car engines to reach the listed number indicating their total horsepower.

What is Torque?

Torque is the force the rotational movement of your vehicle’s crankshaft generates. It is the primary reason the wheels of your car spin when you press down the gas pedal. It is the precise amount of force you apply to an object in a twisting motion.

As this force acts on an object, it translates automatically to work. Simply put, torque is your vehicle’s ability to perform work or a unit measure of strength.

Differences Between Horsepower and Torque

As you can see, the definitions of horsepower and torque are different, though intertwined. This is because one cannot do without the other regarding the overall performance of a vehicle’s engine. It must also be mentioned that the amount of horsepower and torque a vehicle has significantly affects the overall rate of the wear and tear the vehicle experiences.

They share two similarities: both metrics are essentially byproducts of your vehicle’s engine when you switch on the ignition and press the gas pedal. They are also involved in converting fuel and air within the vehicle’s engine into the energy required for your vehicle to move.

That being said, here are the significant difference between horsepower and torque:

1. Horsepower and Torque Measure Different Things

In simple words, torque is a method of measuring force, as mentioned earlier. But horsepower is all about the power the engine transfers to the vehicle’s wheels. This is mostly based on the weight of the vehicle, the distance the car covers, as well as the time it takes to cover that specific distance.

One of the simplest ways of calculating horsepower is to multiply torque, i.e., force, by rotations per minute.

2. Torque is Crucial for Towing; Horsepower Focuses on Performance

Torque should be your ultimate concern or target if you regularly haul campers, trailers, boats, etc. This is crucial as it helps to minimize strain on your vehicle while contributing positively to pulling the extra load.

Torque helps your vehicle start and even navigate hills. This makes it much more powerful and impactful than horsepower as it keeps your car engine running smoothly while hauling heavy loads. 

Vehicles with higher torques – such as heavy-duty trucks, etc. – may require a bit more time in order to accelerate. However, the low-end power nature of torque is responsible for making haulage possible in the first instance.

On the other hand, horsepower is all about the vehicle’s performance. Cars with high horsepower are primarily designed for car owners who want lots of power and speed under the hood. The higher the rating of a vehicle’s horsepower, the faster it will go relative to its overall size.

For instance, a sports car and a large sedan may share the same horsepower rating. However, the sports car will outpace the other vehicle simply because it is more compact or lighter. Vehicles with lots of horsepower also offer exceptional handling on the roads.

This does not imply that vehicles with higher horsepower ratings don’t need torque. They do; in fact, such vehicles rely heavily on torque. However, most vehicles nowadays are designed such that they have the perfect balance between horsepower and torque, which offers the best driving experience.

3. Horsepower and Torque Work Differently for the Acceleration of a Vehicle

As you press the gas pedal of your vehicle, there is a combination of horsepower and torque. But regarding how your vehicle accelerates, both metrics have unique functions. 

Summed up briefly, the primary job of torque is to ensure your car moves when you initially hit the gas pedal, i.e., accelerate. But when the vehicle is in motion, horsepower is left with the responsibility of getting you up to and efficiently maintaining speed for your drive.

4. Horsepower and Torque Have Different Impacts on the Fuel Efficiency

Everyone who desires to purchase a car will probably make fuel efficiency a vital factor to look out for.

Horsepower and torque have significant impacts on fuel efficiency but in different ways. For instance, the more horsepower a particular vehicle has, the faster it burns fuel, whether under standard driving conditions or on acceleration.

On the other hand, a vehicle with a low-end torque burns fuel slowly, depending considerably on your typical hauling and driving habits. This shows the different impacts both metrics have on any vehicle’s fuel efficiency.

Amp Up Horsepower and Torque for Solid Performance

The importance of horsepower and torque when it comes to the overall performance of a vehicle’s engine cannot be overstated. However, knowing the considerable differences between these two performance metrics will go a long way in helping you make the right buying decision whenever you’re in the market for a new or used car.

This doesn’t imply that everything you know about a vehicle’s performance is all lies. Horsepower still matters a lot and continues to be an incredibly useful metric. The only thing is the disproportionate emphasis most people place on it. When you step on the gas pedal, what you generally feel is nothing but torque.

Shop Torques, Converters, and More at Gearstar

Looking to upgrade or replace your torque? Shop with us at Gearstar. We have a range of torques to choose from for Ford, GM, and Mopar transmissions.

For all other questions, send us a line through our online contact form or by phone. You may also check out our resources and support section for how-tos and more.

Dyno Testing for Top-Notch Performance

Dyno testing for top notch performance

Have you ever considered dyno testing your engine? If you are reading this, it simply means you want to learn more about how to dyno test an engine. 

Dyno testing an engine is not rocket science. You start by powering up the engine and adding a significantly controlled amount of resistance. A dynamometer efficiently measures the engine’s horsepower, force, and torque as you perform the test. 

But why should you carry out a dyno test on your vehicle engine? Is it to find out about the metrics, i.e., the number of horses under your hood? 

Why You Should Dyno Test Your Car Engine

Here are some reasons you should consider taking your vehicle for a dyno test:

To Take an Engine On Its First Run

Taking an engine on its first run via dyno testing is a wise move that experts commend. It is easier to establish engine break-in routines specified by ring and cam manufacturers under highly controlled conditions.

As the piston rings seat, a professional can monitor blow-by. Pre-heating and pre-lubing of the engine can be performed before each start.

To Ensure the Car Engine Runs Properly

The use of a computerized dynamometer reveals highly accurate RPM and torque numbers. This implies that the measuring instrument can also measure horsepower accurately.

The technician in charge of tuning your car engine gets a verifiable basis for adjusting the engine’s tuning. In a worst-case scenario, the technician may suggest that you change the engine.

Dyno testing enables the variables that permit the tuning of engines this way. Here are the variables in no particular order:

  • Cam grind and timing
  • Intake manifold selection
  • Carburetor spacers
  • Primary tube length and diameter for the headers
  • The size of the carburetor and jetting
  • Advance curve and ignition timing

As you can see, these variables play a crucial role in tuning a car engine.

To Obtain Full Details/Information of Your Car Engine’s Overall Performance

Dyno testing your engine furnishes you with explicit details about every test. This usually includes the graphs of your engine’s overall performance, the weather condition on the day the dyno test was performed, etc.

Getting these details in a report allows you to personally compare your experiences with the dyno numbers. This informs you to get ready for future modifications or adjustments.

Moreover, additional information from the dyno test can indicate the following details:

  • Volume metric efficiency
  • Horsepower
  • The temperatures of the pistons and cylinders
  • Airflow
  • Torque and peak torque

In other words, a dyno test gives accurate measurements of nearly all engine functions.

To Discover the Temperature of Your Vehicle’s Exhaust Gas

Many vehicle owners/drivers don’t know this, but knowing your exhaust gas temperature is incredibly important. Experts say this metric is even far more essential than torque and horsepower numbers in many cases. When it comes to tuning your fuel distribution, carburetor spacers, size, and jetting, this is a fact.

As a result, vehicle owners who are unaware of this crucial information end up with major engine repairs in the short or long run.

Factors to Consider as You Prepare for Dyno Testing Your Engine

Dyno testing your car greatly boosts the performance of the engine. But here are some factors to consider as you prepare to tune your vehicle via the use of a dynamometer:


Most of the costs generally involved in tuning your engine via a dynamometer require the technician performing the procedure to go through an initial diagnostic run.

One diagnostic run will not be enough, though most car owners seem to think or believe so. 

The best results are obtained when an engine undergoes several runs on the dynamometer in order to determine the engine’s baseline.

The technicians can then diagnose any issue that may have been encountered during the diagnostic runs.

Aftermarket Components

You should also consider the costs of aftermarket parts that may be required when tuning your vehicle on a dynamometer.

You may not need or have to add anything. But the best tuning job is performed when you replace some components with suitable aftermarket components.

Know Precisely What You Are Looking At

Unless you are a specialized mechanic well-versed in dynamometers, you may not know diddly-squat about the tool. This can easily push you to start making assumptions without knowing the true reality of precisely what the numbers are saying.

This is why this procedure should be left in the hands of a professional who knows the ins and outs of a dynamometer. Experts that use dynamometers will explain what the A/F ratio means and inform you if it is a little off and requires the changing of valve timing in order to make it much better, etc.

Leave the adjustments to the experts, but keep an eye on the metrics in case you need to perform the procedure by yourself.

Execute Several Baseline Runs

The best – and most efficient – way of determining the power and overall performance of a car’s engine is by carrying out several baseline runs.

This reveals the vehicle’s state in its entirety before making any modifications or adjustments.

Performing different baseline runs is essential due to the way numerous factors change the performance of vehicle engines.

Determine What Needs to Be Changed before Dyno Testing Your Engine

Do you have any thoughts on the parts or components of the engine that you need to change? This is crucial and must be determined even before dyno testing your engine.

Knowing what needs to be changed or modified saves you a lot of money and time. This is because you would have paid for and gotten every necessary component and tool required to make a successful tuning process on hand.

Getting Dyno Testing for Your Engine

The importance of dyno testing your engine cannot be overstated. A dyno test is an incredibly valuable tool that helps ensure your engine remains in top-notch shape. The optimal performance of your car engine is a crucial element that must never be taken for granted in your regular maintenance routine.

Therefore, locate the nearest specialized engine shop in your locality to assist you with dyno testing your engine. This puts the engine in excellent shape, and you will enjoy its top-notch performance for a long time.

At Gearstar, we perform dyno testing on each transmission and converter. Our team strives to provide customers with peace of mind knowing it’s in perfect condition long after leaving the shop.

Whether it’s a Ford, GM, or Mopar, we’ve got you covered. Reach out or call us today for questions or inquiries.

How to Choose the Right Chevy Torque Converter

Chevy Torque Converter for Chevy GM

It’s important to know how to choose the right torque converter for your chevy GM to ensure it is the rugged ride you expect it to be.

Admittedly, torque converters are a great component in your automatic car due to the wide functions they provide.

For starters, these units help to transmit the power of the engine to the transmission and rear wheels.

It’s even more interesting to note that although torque converters may seem complex, their mode of operation is a simple one.

Now walk with us as we throw more light on this component and how you too can select the right torque converter for your chevy GM.

What is a Torque Converter?

A component that sends the engine’s power to the transmission and rear wheels is called the torque converter.

This component adopts the principle of fluid coupling while at the same time supporting the hydromechanical connection.

Also, fluid is used to aid the operation of the torque converter components including the impeller, stator, and turbine.

Fluid tends to move a turbine, which is a component that drives a series of machines.

Transmission fluid is set in motion within the shell as the crankshaft of the engine spins the finned impeller inside the shell.

The moving fluid goes through the stator before it enters the turbine that is linked to the input shaft and forward clutch assembly of the transmission.

Coupled with that, you’ll find a roller clutch where the stator is mounted and this clutch enables the one-way rotation of the stator.

Torque Converter Multiplication

Torque multiplication occurs when fluid is passed from the impeller through the stator to the turbine’s center at the transmission’s input shaft.

Here, the transmission fluid is spurned around the perimeter of the shell leading to the creation of velocity and fluid in motion.

The fluid is then passed through the finned stator and its movement is rigorous given that it gains more velocity as it moves through the turbine.

As a result, you get an interaction that is two and half times the torque that your engine would’ve provided.

It also follows that 300 lb-ft of torque at the crankshaft can be translated into two to two and a half times the number under acceleration.

The engine drives the torque converter shell, as well as, the hollow output shaft that is linked to the transmission’s front pump.

The pump provides the hydraulic pressure that is required to control shift function and aid in lubrication within the transmission.

What the hydraulic pump does is engage clutches and bands during shifting.

Further, the front pump drive shaft is hollow and its design provides access for the transmission input shaft within the middle.

Fluid passes through this hollow shaft to and from the torque converter.

Complexity in Torque Converters

The complexity in torque converters increases with the presence of a lockup feature with a clutch within the converter.

This lockup feature helps to enhance efficiency and remove slippage that is often evident when using a torque converter.

The torque multiplication ends as the clutch engages and there’s also a direct link between the crankshaft of the engine and the input shaft of the transmission.

Accordingly, this is an aspect where an automatic transmission operates like a manual transmission.

Locking torque converters often feature three-speed automatics and overdrive automatics.

While the majority of overdrive automatics enter a converter lockup in overdrive, the three-speed automatics tend to lock up in any gear range.

Stall Speed and Flash

Stall speed and flash are other terms used in relation to torque converters.

The stall speed can be defined as the RPM range once the engine moves the car.

In this case, the converter tends to stall or load and it also applies torque to the input shaft of the transmission once it attains a certain rpm range.

Flash, on the other hand, is associated with engine size and type, vehicle type and weight, and the kind of driving you intend to do.

Checking Stall Speed

To check stall speed, ensure that your car is in gear at a crawl before the throttle is hit.

On the other hand, it is often advised that you do not experiment with your car using a hard power braking at a wide-open-throttle that is not in motion.

The test may be in a bid to determine the stall speed but this may lead to damage to the engine and transmission.

Over and above that, there are stock torque converters that have a stall speed between 1,800-2,000 rpm.

The need for higher stall speeds may present itself in cases where the horsepower and torque occur at higher rpm ranges.

In a scenario of this nature, you may have a need for the stall speed and maximum engine torque to occur around the same rpm range.

Hence, if the maximum torque is 3,500 rpm the stall speed will be around there.


Good knowledge of torque converters will help you choose the right torque converter for your chevy GM.

This is an important component in your car since it impacts the vehicle’s torque and horsepower.

There’s also the stall speed to consider, flash, as with other terms.

Each of these has been covered above to help you make the most of your ride.

What is an Aftermarket Torque Converter?

what is an aftermarket torque converter

What is an aftermarket torque converter? The torque converter is a vital component of many auto transmission vehicles. It plays a crucial role in starting a vehicle and takes the part of the conventional clutch by readily connecting – and separating – the transmission and engine. 

It is the seamless interaction between the torque converter, the hydraulic energy (generated by special fluid), and the engine (with its mechanical kinetic energy) that powers the transmission for automatic driving. 

In other words, a torque converter efficiently transfers rotating power from a prime mover right to a rotating driven load. It is the latter that helps in connecting the power source to the load within an automatic transmission. 

Therefore, in simple words, the torque converter functions primarily as a mechanical clutch in manual transmission vehicles. 

The torque converter is set between the engine flexplate and the transmission. It is responsible for enabling engines to run while the vehicle is stationary. But as soon as the vehicle starts moving, the torque converter transmits power hydraulically via the transmission fluid. 

An aftermarket torque converter is a spare part designed to work like the factory-fitted torque converter. Many specialists consider aftermarket torque converters the best option whenever there is a need to replace the defective factory-fitted torque converter. 

The major components of a torque converter include: 

  • Brake lining 
  • Stator 
  • Turbine wheel 
  • Torsional damper 
  • Impeller 
  • Lock-up clutch, etc. 

How Does a Torque Converter Work? 

To understand how a torque converter works, highlighting the 3 stages of operation it undergoes is essential. The 3 stages – i.e., stall, acceleration, coupling – are discussed separately. 


This refers to a situation in which the turbine can no longer rotate, despite the application of power – by the prime mover – to the impeller. Moreover, the application of enough input power assists the torque converter to generate maximum torque multiplication. The ensuing multiplication is known as the ‘stall ratio.’ 

The ‘stall’ stage of the torque converter’s operation lasts briefly, especially when the load starts moving initially because there will be a considerable difference between the turbine speed and pump. 


Coupling gives rise to fuel economy when the lock-up clutch is applied. This is the point at which the turbine achieves up to 90 percent of the impeller’s (an internal component of the torque converter) speed. 

At this point, one can liken the operation of the torque converter to that of a simple fluid coupling since torque is no more apparent. 


A situation where the load accelerates, but there is a significant difference between the turbine speed, and impeller causes the torque converter to produce torque multiplication that is far lesser than what is available under stall conditions. 

However, what determines the amount of multiplication generated is the real difference between the turbine speed and the pump. 

What are the Internal Components of a Torque Converter? 

The torque converter has 3 major internal components that, without them, the unit cannot operate effectively.  

The internal components are the stator, turbine, and pump. Another vital component is the transmission fluid that works by moving through these significant internal components. 

Let’s take a closer – but brief – look at each of these significant internal components of a torque converter: 


Stators can be found right in the middle of torque converters. Its primary duty is to redirect the transmission fluid just before it gets into the pump again. 

The stator comes with an internal one-way clutch that enables it to freewheel at specific operating speeds. Nevertheless, this internal component is situated on a fixed shaft. 


The output shaft connects the turbine to the transmission. When the turbine spins, its operation causes the transmission to set the vehicle in motion. As soon as the transmission fluid exits the turbine, the latter moves opposite to that of the pump and the engine. 


A torque converter’s housing is connected to the engine’s flywheel while, on the contrary, the fins of the pump link to the housing. The pump spins and then pushes the fluid in an outward motion, operating like a centrifugal pump. 

When the pump operates, it helps in creating a vacuum that conveniently attracts even more transmission fluid toward the torque’s center, and then it enters the turbine straightaway. 

What Sets an Aftermarket Torque Converter Apart? 

An aftermarket torque converter has several benefits that many other spare parts don’t bring to the table. 

Two notable benefits of aftermarket torque converters are: 


A few aftermarket torque converters come equipped with what is referred to as a ‘lockup’ contraption. The primary job of this mechanism is to readily bind the vehicle engine to the transmission in a rigid manner when their speeds are nearly equivalent. 

This is the operation that prevents loss of efficiency and incredibly high levels of slippage. 

The lockup mechanism’s action also helps to significantly boost fuel efficiency – even up to 65 percent – while simultaneously eliminating wasted power. 

However, uninterrupted high levels of slippage could make it somewhat tricky for the torque converter to readily disperse heat. 

When a torque converter cannot dissipate heat, it damages the elastomer seals. These seals are primarily responsible for retaining or sustaining fluid within the torque converter. 

Over time, the fluid within the torque converter starts leaking, and when there is no more fluid within it, the machine stops working altogether. 

Torque multiplication 

A regular fluid coupling and an aftermarket torque converter do not perform the same way. The former’s primary responsibility involves matching the rotational speed but cannot multiply torque. 

On the other hand, an aftermarket torque converter quickly multiplies torque, especially in situations in which output rotational speed is meager. In such cases, fluid from the turbine’s curved vanes deflects off the stator. 

Furthermore, fluid deflection can only occur when the stator is temporarily locked against its one-way clutch. This results in something equivalent to a reduction gear. 

Torque multiplication can also come about when there is a significant difference between both input and output speeds. 


If the torque converter in your vehicle fails, the vehicle transmission will suffer from it. Faulty torque converters lead to loss of power and can even cause transmission gears to slip unceremoniously because of a reduction in the seamless flow of the transmission fluid. 

Using an aftermarket torque converter has several benefits, thanks to the operation of some components like the stator, impeller, turbine, etc. This is why the aftermarket torque converter is the perfect option if you need to replace your vehicle’s faulty, factory-fitted torque converter. 

The Ultimate Guide to the 4L80E Transmission

Overview of the 4L80E Transmission - Gearstar Performance

The 4L80E transmission is an automatic transmission designed by General Motors. Learn more about this legendary transmission.

The 4L80E transmission was introduced in the GM C/K Trucks line-up – to the delight of motorists – in 1991. The legendary TurboHydramatic TH400 automatic transmission was the 4L80E transmission’s immediate predecessor. It is constructed to a great extent on the 400 in strength and parts. The 4L80E also features a lock-up torque converter, an added overdrive gear, as well as state-of-the-art electronic controls. This automatic transmission has remained in production through the 2009+ model year.

In this post, you will learn more about the 4L80E transmission and its variant, i.e., the 4L85E. The latter is constructed such that it can efficiently handle heavy-duty use. Every reference to the 4L80E also applies to this variant, except where stated otherwise. 

Note that the terms’ 4L80′ and ‘4L85’ may be used without adding the suffix, ‘É.’ This is because every GM automatic is electronically controlled now and, therefore, doesn’t need differentiation. 

Let’s get to the meat of the matter.

The Development of the 4L80E Transmission

As mentioned briefly earlier, the 4L80E automatic transmission was directly developed from the TH400 transmission. The latter is a challenging and enduring transmission at GM – as well as other marques. It was practically the last hold-out of the entire old-school automatics with no overdrive or lock-up converter.

GM quickly recognized a gap revealed by the rapidly expanding success of the 4L80E/700R4 automatic transmission. Although the 700R4 was a tough transmission, it could not hold a candle to the TH400 transmission. 

And for this particular reason, GM had no choice but to start developing a pretty heavy-duty automatic overdrive.

GM relied heavily on – and used – several parts or components and designs derived from the TH400 transmission when developing the 4L80E. But the added overdrive gear gave the 4L80E an edge over its predecessor, even though it required a somewhat longer case and an extra gear set.

The rear tail housing bolt pattern was not tampered with in any way. However, its indexing bore diameter was efficiently changed. The 4L80E transmission features a large 32 spline output shaft – much like the TH400 transmission – in the numerous 2WD and 4WD applications.

The 4L80E features a die-cast aluminum case, just like most other GM automatics. However, the 4L80E never featured a removable bell housing, unlike the 4L60E automatic transmission. Instead, the 4L80E transmission showcases an integrated bellhousing with the Chevrolet 90-degree engine bolt pattern only.

In 1991, GM trucks rolled out into the market, bearing the 4L80E automatic transmission. This included the Silverado, Sierra, Suburban, Hummer H1, etc.

The 4L80E automatic transmission is by no means perfect and has its share of glitches. However, it became a huge success and continued to be enhanced throughout its production span, even with extra changes entering when required.

In 2002, the 4L85 automatic transmission entered the market. A few differences between this transmission and the 4L80E include a 5-pinion reaction gearset, a 5-pinion output gearset, etc.

GM specified a brand-new automatic transmission fluid formulation in 2006, though this development was not regarded as a transmission change. The company required this fluid formulation’s warranty in the 4L80E series. Dexron VI, another brand, highly superseded its previous transmission fluids, claiming that it has significantly improved the transmission performance as well as a more extraordinary fluid life and transmission.

The 4L80E Automatic Transmission Technology

Every 4L80E automatic transmission makes use of electronic controls, which are generally from the Powertrain Control Module. Some vehicles using this automatic transmission come with shift maps that the driver can select, based on usage, including towing, etc. 

Part of the Powertrain Control Module’s strategy includes shift stabilization, which contributes significantly to reducing hunting.

The torque converter – when applied in factories – is heavily controlled via a PWM lock-up solenoid for seamless lock-up action. Despite this, several performance aficionados always prefer to efficiently reprogram the 4L80E automatic transmission in order to run as a very simple, ON-OFF solenoid.

The H1 received a 4L80 along with its dedicated T42 transmission computer in 2004. This automatic transmission also arrived with a considerably enhanced Park/Neutral safety switch and modified transmission line pressure solenoid. Other General Motors applications are still going to follow soon.

The TCM (Transmission Control Module) refers to the highly adaptive learning computer smartly integrated within the transmission valve body. It communicates efficiently with the Engine Control Module through the onboard vehicle CAN bus network. 

This is a departure from – and a return to – preceding automotive control systems within the industry. This is because the earlier versions of electronic transmissions made use of a separate control module. This module was later integrated right into the Engine Control Module and is now known as the ‘Power Control Modules.’

But now, this high-speed CAN network permits an incredibly high rate of data sharing between these units. This occurs in order to reach a collaboration between transmission and engine functions.

Since the 4L80E automatic transmissions are – on certain occasions – used in conversion applications with the earlier non-PCM-controlled engines, GM as well as aftermarket control modules are necessary. And they are now used to control the operation or function of the transmission in these specific scenarios.

The Specifications

When you see the nomenclature of the 4L80E, it readily informs users that this is a longitudinally-mounted, 4-speed transmission designed for vehicles that weigh nothing less than 8000 lbs. The 4L80E has an RPO code – i.e. ‘MT1’ – manufactured domestically in GM’s Willow Run and Ypsilanti plants.

Here are the 4L80E ratios it features in each gear:

  • First: 2.48
  • Second: 1.48
  • Third: 1.00
  • Fourth: 075
  • Reverse 2.07

The maximum output torque of the 4L80E transmission is 885 ft. lbs. 

While the top engine input torque is 440 ft. lbs. Die-cast aluminum is the transmission’s case. And it was designed for vehicles that weigh up to 8,000 lbs. GVWR as well as with engines up to 440 ft. lbs. of torque.

However, the 4L85 was primarily designed for automobiles that weigh up to 16,500 lbs. GVWR as well as with engines up to 460 ft. lbs. of torque. This transmission has an incredible towing capacity as it was up-rated to 22,000 lbs.

The 4L80E series requires a shifter with a 7-position quadrant: P, R, N, OD, D, 2, 1. The torque converter on this automatic transmission is a fluid turbine drive, much like those found on its predecessors, e.g., the 700R4, 4L60, TH350C.

The 4L80E also comes with a lock-up pressure plate for direct, mechanically-coupled driving from the engine crank. It is 26¼ inches long and boasts a 310mm torque converter.

Applications of the Transmission

The 4L80E automatic transmission has several applications, such as:

  • Speed-sensing
  • Transfer case adaptability
  • Jeep conversions
  • Engine compatibility

Final Thoughts

By now, you already know that the 4L80E automatic transmission is intelligently designed to meet transmission challenges. This implemented automatic transmission from the legendary General Motors has an extraordinary record in conversion situations and will always leave you super-impressed.

545RFE Transmission Specs and Schematic

545RFE Transmission - Gearstar Performance Transmissions

The 545RFE transmission is an electronically controlled unit that was great for its time until it was replaced bu the 65RFE and 66RFE. Read below for specs and more information.

The automobile universe witnessed the introduction of the 545RFE/45RFE transmission in 1999 Chrysler models. The transmission was a perfect fit for 2-wheel-drive vehicles as well as all-wheel-drive automobiles. 

The 545RFE transmission, formerly known as the 45RFE – introduced and popularly seen in the Jeep Grand Cherokee of 1999 – is highly notable for its three planetary gearsets instead of 2 planetary gearsets commonly used in a 4-speed automatic.

The 545RFE also features the following:

  • Three multiple disc holding clutches
  • Three multiple disc input clutches
  • A dual internal filter system (one filter for the fluid cooler return system and the other primary filter for transmission sump)

The 545RFE transmission, based primarily on the 45RFE automatic, was used extensively in Chrysler’s entire fleet of rear-wheel heavy-duty trucks, except for coupes and sedans.

545RFE Transmission: Specs

But back in 1998, Chrysler has introduced the 45RFE in the 1999 WJ Jeep Grand Cherokee. This transmission was paired remarkably well with the 4.7 L PowerTech V8 engine. The ’45’ refers to its torque rating, i.e., ‘5,’ while ‘4’ represents the number of forward gears. ‘RFE’ refers to the ‘rear-wheel-drive application and full electronic controls.’

But by 2001, the 545RFE transmission was produced due to a taller, extra overdrive ratio and programming changes. The new transmission had a standard axle ratio that resulted in 2000 revolutions per minute at the engine, allowing you to cruise at 110 km/h (70 miles per hour).

The 545RFE transmission found its way to several SUV and truck applications from 2001 to 2012 with Jeep Commander and Jeep Grand Cherokee models that sport higher output Hemi engines. It could also be found in several Dodge Durango models within this period.

Although the engine yield was 200 rpm less than the 45RFE, the outcome was a considerable decrease in noise and fuel consumption. Now, the 545RFE transmission had six forward speeds and one reserved for kickdowns.

The engineering of the 545RFE transmission closely resembles that of the solid Torquefiles or an up-to-date version. The 545RFE transmission had a tall 3.00:1 first gear for initial acceleration.

The reverse was designed to be equal to first gear to accommodate heavy loads easily. When the 545RFE transmission was launched, it had the broadest range of gear ratios within its class. Even the factory where the transmission was made was also brand-new.

According to experts, the 545RFE comes with 2 overdrive gears. These are relatively close to each other due to the available size. The top 0.67:1 was probably chosen since that was the largest one that could easily fit without enlarging the transmission, making it too big for the organization’s automobiles.

To be clear, the following are the 545RFE gear ratios:

First gear – 3.00:1

Second gear – 1.67:1

Second gear (Prime) – 1.50:1

Third gear – 1.00:1

Fourth gear – 0.75:1

Fifth gear – 0.67:1

Reverse – 3.00:1

The capacity of the 545RFE transmission is 10.5-11 l, while the fluid type is Dexron 3-6 or MOPAR +4.

Some models with the ‘Tow/Haul’ mode were able to make faster shifts to cut wear on the 545RFE transmission. This considerably minimized the search for gear by holding the lower gears for extended periods. It was also possible to choose lower gears when traveling downhill to boost engine braking.

The computer-controlled 545RFE transmission comes in a burnished, one-piece die-cast aluminum casing. The casing was ribbed to increase torsional rigidity. Early transmission units took up to 6.6 quarters (6.2 liters) of ATF+3 fluid, while later versions took the same amount of ATF+4 fluid.

The gear ratios were designed to provide reserve torque as the transmission was highly suitable for the large torque band of the VM 2.8 diesel, Hemi V8, 4.7 V8, and 3.7 V6.

However, in 2009, the computer was programmed so that drivers could easily select the highest gear the 545RFE transmission would shift to. This made it easier for vehicles with this transmission to tow other vehicles, climb hills, and descend without any issues.

Common Issues with the 545RFE transmission

Here are some of the common problems that the 545RFE transmission showcases:

Solenoid Pack

Since the this transmission has zero transmission bands, the 545RFE – which is electronically controlled – relies heavily on a solenoid switch pack to efficiently direct fluid to the proper clutch pack for smooth gear engagement.

If something goes wrong and the solenoid pack becomes defective, there will be no gear engagement, failure to engage overdrive, stalling of the engine seamlessly, and ‘limp mode.’


This is another common challenge when moving parts within the transmission generate much more friction heat than the ATF can siphon away.

The primary cause of this problem involves the towing of heavy loads, multiple shifting of transmission on mountain roads, and driving in heavy stop/go traffic.

Delayed and Slipping Gear Engagement

The 545RFE transmission pump comes with a bit of a valve mechanism, which controls the fluid pressure that the torque converter transfers.

If the valve mechanism becomes faulty, you will experience significantly delayed gear engagement, stalling, torque converter/transmission overheating, reduced fuel economy, and slipping.

Harsh or Delayed 3-4 or 4-5 Shifts

Users of this transmission may experience a severe or unusual delay of 3-4 or 4-5 gear change. In such instances, it appears as if the transmission is reluctant to go into that specific gear.

This problem is linked to valve body issues in which the material used for making one of the check balls has somehow broken down so severely that fluid easily gets past and engages the underdrive clutch during the shifts.

The only way to solve this problem will be to install an upgraded #2 check ball made of a tougher material.

Four and five-speed automatic transmissions have up to 90 percent of interchangeable parts, and this makes it easy to perform repairs. The 545RFE transmission is reliable and highly durable, making serious damage a scarce thing. 

Although it was originally developed and designed to be used by heavy-duty engines, it is very compact. The use of highly active electronic control systems significantly reduced the valve body and drive shafts. 

Differences Between the 45RFE and 545RFE Transmission

The 45RFE and the 545RFE transmissions are mechanically identical. The notable difference comes down to software.

The 545RFE transmission has an electronically activated fifth gear. You will also notice that the unit control module and solenoid pack is different in both transmissions.


This transmission was excellent in its heydays. It was an electronically controlled unit that Chrysler produced and used extensively until it was replaced by the 65RFE and 66RFE automatic transmissions. For information on other performance transmissions and torque converters, contact us today.

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.

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 pound-feet 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.

The 4L70E Transmission: Up Close and Personal

4L70E Transmission - Gearstar

The 4L70E automatic transmission is undoubtedly a workhorse gear mechanism that offers more excellent reliability and a good deal more power. Read on for specs and more information.

The 4L70E is a 4-speed automatic GM transmission with up to 5 gears, including reverse. The 4th gear of the 4L70E is a .70 overdrive. It also shares the same basic design – and case – with the 4L60E and the 4L65E. This 4-speed automatic transmission is designed with considerably lightened materials to support much better fuel efficiency, electronically-controlled shifting, and four speeds. It is the last iteration of a unique design launched long ago, starting with the 700R4.

Here are the specs of the 4L70E:

  • Production: 1992 – Present time
  • Manufacturer: General Motors (GM)
  • Torque Converter Lock: Yes
  • RPO Code: M70
  • Overdrive: Yes

Outer Case Material

  • Aluminum + 2 removable bellhousing
  • Controlled by Computer: Yes, via the engine ECU.

Gear ratios are as follows:

  • First gear: 3.06
  • Second gear: 1.62
  • Third gear: 1.00
  • Fourth gear: 0.70
  • Reverse gear: 2.29

The 4L70E automatic transmission weighs approximately 133 lbs. dry.

The Unique Differences Between the 4L70E and 4L60E

There are several differences between the 4L70E and the 4L60E. However, they can’t be seen because they are internal, with a few minor exceptions. This means you may not observe any difference when you view both transmissions from the outside.

For instance, the output shaft is different, and the 4L70E now bears an input shaft speed sensor. 

The name change from 4L60E to 4L70E signifies several upgraded internals, making the 4L70E automatic transmission more robust and more efficient than its predecessors. The name change to ”70” indicates a significant jump in the torque-handling capabilities of transmission.

Here are some of the few – but significant – structural improvements that have been made to the 4L70E, which has boosted its reliability and efficiency over its predecessors:

  1. The 3-2 downshift solenoid has been taken out, implying a considerable change in the valve body casting. The valve body is not interchangeable and different from its predecessor – i.e., the 4L60E – since the 3-2 solenoid location has been cast shut.
  2. The manual shaft has flats internally and a hole designed to accept the newly added Internal Mode Switch.
  3. The schematics, as well as internal wiring, have been changed entirely. The connector pin in this automatic transmission is far different from the ones found in its predecessors.
  4. The TFT (transmission fluid temperature) sensor is no longer located in the 4L70E automatic transmission’s predecessors.
  5. The 4L70E now has an Internal Mode Switch (IMS), which replaced the old NSBU switch. The NSBU was external, while the IMS was internal.

Other minor changes include the total removal of the Parking rod and pressure switch. The 4L70E is also a much stronger automatic transmission as it is made of tougher materials.

The 4L70E and the 4L60E transmissions look very much alike, except for the differences in the internals. Swapping parts from one to the other is a very poor decision, primarily if you don’t ensure that those components share the same GM Parts number.

In other words, don’t even think about it. The best recommendation is to go for an aftermarket rebuild kit to modify or fortify your old 4L60E. You can’t convert the 4L60E to 4L70E.

How to Tell Two Transmissions Apart Without Opening Them Up

If you are looking for a particular transmission in stock GM automobiles, you can tell the 4L70E apart from the 4L65E without opening up both. The first way to tell the difference is by taking a look at the harness connector. The 4L70E transmission has a neon blue or black harness connector.

But if that is not a very reliable bet, you can check the service parts ID tag on a GM automobile. An ”M70” symbol should be o the tag, especially if the automobile’s stock transmission is a 4L70E. 

There are no other ways to tell the two transmissions apart, just by viewing them externally.

Can the 4L70E Replace the 4L60E Transmission?

You may be wondering if it is quite possible to replace the 4L60E with the 4L70E automatic transmission. Yes, it is possible: the 4L70E will bolt right in with some minor exceptions.

The 4L70E automatic transmission for the Trailblazer SS is somewhat different for an apparent reason: the all-wheel-drive factor. The torque converter for both transmissions is the same. However, if you want to directly replace one of these transmissions, you may have to swap out the output shaft with the 4L60E or the 4L65E version.

Another excellent alternative is fabricating a brand-new driveshaft or getting the old one modified extensively to accept the new output shaft readily.

The 4L70E Automatic Transmission: Built for Toughness

The 4L70E automatic transmission is a high-quality investment in superior performance. And installing it is not a plug-and-play business. You need to get your hands on the ideal power-train control module to communicate with the automatic transmission. In a few cases, you may have no choice but to re-pin the wiring harness.

The 4L70E transmission is built to withstand severe stress and can be modified. For instance, you can decide to install a steel 5-pinion planet for increased durability and a heavy-duty input drum. Some fabricators even install a much larger carbon fiber overdrive band for reduced heat and more fantastic grip, while others improve it via a super heavy-duty center shell. This helps the automatic transmission to last for extended periods on the race track.

Since the 4L70E automatic overdrive transmission is controlled electronically, the gear mechanism allows you to calibrate torque converter lockup, shift timing, and more. This makes the 4L70E much more versatile than the older throttle valve cable predecessor, the GM 4L60s.

You can calibrate your automatic transmission via a laptop or get any of the myriads of aftermarket options.

If you are looking for a pretty solid GM transmission within the 650 HP and ft./lbs. Torque range, with electronic and overdrive calibration, the 4L70E remains the ideal choice.

The Takeaway

The 4L70E automatic transmission is undoubtedly a workhorse gear mechanism that offers more excellent reliability and a good deal more power. Upgrading to the 4L70E automatic transmission is your best bet if you are looking for or require a transmission capable of working up beyond the realm of 425 ft./lbs. of torque and 450 HP and below the 650 HP and ft./lbs. of torque range.