Much to my surprise, I learned that transmission weight can determine the way we go about working on our car, what we’re able to actually do, shipping costs, performance, and more.
How much does a transmission weigh? Most transmissions generally weigh between 100 and 400 pounds (45 to 181 kg), although the type of vehicle can cause this number to be much higher.
The key to the transmission is in how it’s designed and functions, which is also related to weight, by transmitting power from the engine to the wheels.
Without it, you could have the most powerful engine in the world, but you’d still never leave your driveway.
Like any vehicular element, not all transmissions are created alike, and neither do they all weigh the same.
The weight of the transmission
While most transmissions are within the 100 and 400 pound mark, there are, however, some special exceptions, though for the general public and typical vehicles, this is the common weight range of a transmission.
Why does transmission weight matter?
You might need to know the answer if you’re thinking about working underneath your car, on the transmission itself, buying parts for it, or listing it for sale. Regardless, it’s a helpful piece of data to understand.
Today, we’re not only going to give you the answer to transmission weight, but we’ll also be breaking down the ins and outs of the answer so you can be a well-informed driver. Ready to learn more? Let’s rev it up!
Common Transmission Weight
As stated above, depending on the make and model of your car, your transmission can typically weigh anywhere between 100 and 400 pounds.
It should be obvious that the size and weight of your transmission will increase as you size up your vehicle. This means a smaller sedan will have a more lightweight one than a minivan.
Look for models such as a front-wheel-drive sedan to have transmissions that weigh around 100 pounds. A large van or SUV may have one at 400 pounds or heavier. When it comes to transmission weight, front-wheel drive vehicles and rear-wheel drive ones do no show much variation.
The number of speeds available on your transmission
Keep in mind that while you may be able to lift a small transmission by one hand, it’s always wisest to use a cherry picker or a transmission jack when you’re working with one.
Which Is Lighter: Automatic or Manual Transmissions?
Later, we’ll discuss the high-level differences between a manual and automatic transmission, however it’s only natural to wonder which of these two types weighs the most. In general, there is only between 50 and 75 pounds of difference between the weight of automatic and manual transmissions, with the manual most frequently being lighter. Still, it’s helpful to make the comparison, especially if you’re in the market for a new one for your car.
In many cases, a manual transmission is the lightest bet. This is compared to automatic models that possess the same torque capabilities and gear ratios. Its heavier size helps to explain why automatic models have poorer fuel economy and drive train loss.
Why do automatic models weigh more? The answer lies in their makeup. Automatic transmissions are enclosed in a cast iron case, while many manual models rely on an aluminum one.
This difference alone accounts for a weight range of between 20 and 30 pounds.
There are also the hardware differences to account for. In general, an automatic transmission includes more parts than a manual one. This requires both the system itself, as well as its housing, to be on the larger and heavier side.
Does this mean an automatic transmission is heavier and therefore makes your car slower? Not at all.
The weight difference is not significant enough to affect performance. This means you should opt for the model that you prefer.
Some lean toward a manual transmission for the hands-on driver control and the way it allows them to live out their childhood dreams of owning a particular vehicle, such as my own personal favorite, the Lamborghini Countach. Others prefer the smooth ride and easy operation of an automatic model.
What Is the Heaviest Transmission Model?
To date, one of the heaviest known models of transmission is the Allison 4500 found in the Medium Tactical Vehicle Replacement (MTVR). This seven-speed transmission is designed to withstand up to 1200 foot-pounds of input torque, even in a vehicle with up to 60,000 pounds of gross weight.
The Allison 4500 is mostly used in purpose-designed military vehicles, though it has gotten some commercial use in the firefighting sphere.
Using Transmission Data Wisely
It’s helpful to know the weight of your transmission, especially if you’re planning to take it in for a replacement.
In some cases, you may even need to ship it off for repairs or have a replacement unit shipped to you. Knowing the weight can help you calculate your shipping expenses ahead of time.
If you’re unsure of the exact weight of your transmission, take it to your local mechanic who can safely weigh it for you. This is recommended over trying to disassemble and measure it yourself, which can pose a slew of risks to your physical safety.
Car Transmission 101
Now that we’ve sorted out various transmission weights, let’s take a quick review of what this piece of equipment does.
What does a transmission do?
In short, a transmission absorbs the rotational power that your engine generates, then delivers it to your vehicle’s wheels. Its basic function is to control the level of speed and torque available to your drive wheels.
What types of transmissions are there?
There are two types of transmissions: manual and automatic. Manual transmissions require the driver/operator to shift or change gears as they drive, while automatic transmissions do the shifting of gears itself as speed and task requirements change during driving.
Now let’s explore the highlights of each.
A manual transmission features a gearbox that adjusts speed and torque for different driving conditions. It works according to a principle known as gear ratio.
In a basic transmission mechanism, there are three main components: the input, intermediate shaft, and output.
The input connects to the intermediate shaft to keep it rotating at a constant speed. Meanwhile, the intermediate shaft connects to the output gear set, the gears of which turn at varying speeds depending on the gear ratio.
When you change the gears, you affect these ratios, which affect the speed and torque of the vehicle. These ratios work in a converse manner, meaning that as you increase torque, you lower speed and vice versa.
For instance, a three-speed mechanism will have the following ratios:
- 1st Gear: Low-speed output, high wheel torque
- 2nd Gear: Medium-speed output, moderate wheel torque
- 3rd Gear: High-speed output, low wheel torque
When you’re going up a steep incline, you need more torque. In this case, your gearbox will reduce the speed at your transmission, generating higher torque at the same power input.
Gear and Shaft Connections
Note that the output gears aren’t fixed with the output shaft. Rather, there is a slight clearance present. One gear affixes at a time, giving the output shaft the speed of that connected gear.
The gears affix to the shaft via a hub attached between them. A sleeve lies on top of the hub. As the sleeve moves, it serves to connect each appropriate gear with the shaft.
The complication? The hub and gear operate at different speeds under normal operation. This renders the sleeve-gear connection impossible to achieve.
A synchronizer ring, paired with what’s known as a friction cone, can help to align the gear speed with the sleeve for a smooth connection.
When you want to change the gear, you’ll need to disengage the clutch, which discontinues power and causes a momentary drop in speed. This explains why anyone with a manual transmission is used to a bumpy ride!
Most high-performing automobiles come equipped with an automatic transmission.
Compared to the gear pair that controls an automatic transmission, an automatic one centers on a planetary gear set, or epicycloidal. Manufacturers developed automatic transmissions to take care of the start-stop power discontinuation that occurs in manual models.
Brazilian engineers developed the first automatic transmission in the early 1930s, selling the prototype to General Motors. In turn, GM debuted the “Hydra-Matic” transmission in its 1940 Oldsmobile.
The main components of a planetary gear set include:
- Ring gear
- Sun gear
- Planet gear
Each set features two inputs and one output. By giving different speeds to the ring and sun gears, you can achieve varying speeds at the output. Locking one part makes the others change pace, delivering various gear ratios.
In direct drive, the input and output shafts rotate at the same speed. In overdrive, the output shaft turns faster than the input shaft.
Planetary Gear Control
In a simple automatic transmission, there are two planetary sets. One of the inputs of one set attaches seamlessly to the output of the other. In other words, they form one cohesive component.
A transmission hydraulic system works in conjunction with a clutch pack (set of metal and friction discs), oil pump, and valve body to control the planetary gear sets.
The planet gears connect to one another via a common carrier. This allows them to spin on shafts known as pinions, attached to the carrier. As they’re in a constant mesh, you can change gears without engaging or disengaging any of them, unlike with a manual transmission.
How does the transmission know which parts of the planetary gear system to assign as the input gear, output gear or as stationary?
Brake pads and clutches take care of this task. Brake pads can tighten to make a ring or sun gear stationary or loosen to allow it to spin. The hydraulic system controls which of the two actions it performs.
When the metal discs in the clutch pack press together due to mechanical, hydraulic, and electrical design, the clutch engages. In turn, this can cause a planetary gear to become an input gear.
Or, it can stop it and turn it stationary instead. The planetary gear connection determines how the corresponding components move, which translates to gear ratio. The planetary arrangement controls how much power the transmission sends to the remainder of your car’s drivetrain.
Even under load and without a clutch, an automatic transmission allows drivers to shift between gears with ease, helping them eliminate the awkward handling that’s become the trademark of some manual versions.
Main Components to Know
An analysis of transmission weight must take into account the various components that comprise a transmission. Though these will vary depending on whether you have a manual or automatic model, here are the primary pieces to know:
- Input shaft
- Output shaft
- Pressure plate
- Shift fork
- Planetary gears
- Torque converter
- Oil pump
- Valve body
- Computer controls
- Gaskets and seals
Keep in mind that these components are those that come standard on manual or automatic transmission models. There are other models, including semi-automatic and dual-clutch transmissions, that have a unique set of gear.
There is also an emerging model known as a Tiptronic transmission, also called a Sportmatic or Steptronic transmission. These are essentially automatic models that can be controlled either manually or via computer. Again, these may have unique components and controls that aren’t included in manual or automatic models.
Transmissions to Tools: Advice You Can Trust
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