Dog Box Transmission Explained — The Magic Whine


The transmission is an essential component of a vehicle. It is the gearbox of the car. Without it, you can’t control your speed, and you can’t move forward or backward. The transmission system is made up of a few major components that work together to make the car move and stop. Today, there are a wide variety of transmissions, and there are systems that provide completely different types of power transmission in race cars. One of those is the so-called Dog Box transmission. These are a staple of any serious race car builds.
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Manual Gearboxes

If you’re driving a vehicle with a manual transmission, you know that each time you shift gears, you have to use a clutch to disengage the engine from the transmission. In most cases, this means taking your foot off the gas pedal and pushing down on the clutch pedal with your left foot.

Dog-box transmissions are sequential transmission systems. We should try to explain the sequential transmission systems in the simplest way from a driver’s perspective without using engineering terms and going too deep into the subject matter.

What Is A Sequential Gearbox, and How Does It Work?

Sequential transmission, which is used in motorcycles and racing vehicles, is preferred by those who want to go forward in vehicle modification.

This type of transmission is structured to work faster than conventional manual gearboxes by default. Downshifts and upshifts are done manually with a sort of automated system. Therefore, it provides a very serious time advantage compared to conventional transmissions.

To start the vehicle and move the vehicle, you press the clutch and take off just like you would with a regular manual gearbox. So there is a clutch. But, you will not have to depress the clutch in later gear changes until you need to stop.

When you pull the gearshift lever to yourself, you shift up a gear, and when you push it, you go down a gear, but you have to match the revs to your speed. The gear ratios are sequential, hence the name. Which means you cannot jump from 4th to 2nd or 1st to 3rd. This usually makes sequential gearboxes a pain in the ass to drive in traffic, but it also offers niche convenience while racing.

It is indispensable in the world of motorsports because it allows the gear shifts to be made very quickly with power loss kept at a minimum level. Such fast gear shifts allow the vehicle to reach top speeds much faster. It also provides greatly simplifies the process of shifting gears for the driver.

Now we know a bit more about the sequential gearbox, we can explain the Dog-Box transmissions in more detail.

What Is a Dog-Box?

A “dog” in engineering terms means a part used to lock two components. The use of this term in the automotive industry comes from an integrated transmission part called a dog ring or a dog clutch.

This part looks like dog teeth, and it is used for connecting two gears while the vehicle is in motion. Dog clutches are used in manual car transmissions to lock different gears on the rotating input shaft and output shaft.

The timing arrangement ensures smooth engagement by matching the shaft speed before allowing the dog clutch to engage. It means the next gear is always ready. If you’re in a middle of a race, this type of transmission saves a tremendous amount of time for sudden gear changes.

Dog-Box transmissions are generally preferred in special cars as well. Until recently, the Abarth 695 Biposto was able to offer its Dog-Box type transmission as an option. That was the only production car with a dog box option. There are a couple of good reasons for it. For one, It’s an expensive modification.

Also, using sequential gearboxes in traffic can be tiring and its life is shorter than ordinary manual gearboxes. Parts simply wear out faster than in any conventional manual gearboxes. Interestingly enough, dog box transmissions are used in some trucks as well. They’re not very common anymore, but they’ve been around since the 1950s.

Synchromesh vs Dog-Box transmissions

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Usually, a manual transmission will allow any gear ratio to be selected at any given time, but a sequential manual transmission will only allow a shift to the next higher or lower ratio. The shifter is usually floor-mounted, but some cars also have a column-mounted or console-mounted (dash-mounted) shifter.

Have you ever seen a dog box transmission? If you have, you know it is different from any other kind of transmission. You’re probably wondering what makes it so special? The main physical difference you can usually notice is in the shape of gears.

While synchromesh transmission gears have a traditional helical structure, dog-box gears are often (but not always) straight cut. This gives the dog-box gears the ability to engage when spinning at different speeds. That being said, there are plenty of dog-box transmissions that feature helical gears as well.

When driving a dog-box transmission, one should strongly jam the gear lever as quickly as one can. This makes it very tiring to drive on a day-to-day basis. In fact, changing the gears slowly and using the clutch is the worst thing that can be done to a dog-box transmission. Because of that, most regular street cars are fitted with synchromesh manual gearboxes.

Synchromesh Explained

With the synchromesh system, the helical gears are constantly rotating. In order to fix the gears, a part called the sleeve slips over the synchronous gear and locks it, thus putting the gear into action. The collar acts as a bridge, allowing the cuff to enter easily.

Most present-day vehicles are fitted with a synchromesh gearbox. They are dependable, quiet, and easy to use. The clutch should be used in every gear change. Synchromesh is the part in the gearbox that facilitates shifting and adjusts the movement of the two gears.

Located inside the gearbox itself, this part provides the power flow to the gear wheels working in gear change. In short, the synchromesh enables the wheels to switch between each other when shifting from 1st gear to 2nd gear. The noise that occurs during hard gear changes comes from the synchromesh, and the sharp gear changes damage the synchromesh.

Benefits of Sycnrhomesh And Dog Box Gearboxes

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For a driver, the difference between a dog and a synchro transmission can be felt by the difference in rpm output from most gears of most engine types. The first 500–750 rpm of a gear is the most heavily utilized due to the higher demand for power early in the acceleration phase.

Within this initial speed range, the synchro has the best throttle response and higher peak power, while the dog gear has the best acceleration to peak torque and fastest gear selection possible. Race cars usually run on higher RPMs, that’s one of the reasons why they prefer to have a dog-box.

Is a Dog Box Worth It?

Overall, it all depends on how you as a driver want to use your transmission system. Do you want quick gear changes and much more torque at higher RPMs while making a lot of noise? If so, the dog-box transmissions could be a viable option. If you prefer a more reliable, comfortable, and silent ride, you should definitely go with a synchromesh system.

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