This article is about one of the most important parts affecting both the speed and handling of a race car.

Previous parts concerning the construction of racing cars BODY


The transmission of a race car consists of several key components and assemblies.


In motorsport, clutch discs with a higher coefficient of adhesion are used, which allows more torque to be transmitted from a powerful engine. For example, ceramic or carbon fiber lining. At the same time, at high moments, the number of disks is increased.

It may also be necessary to use a more powerful clutch basket.



Drive (axle shaft)

After converting the moment in the gearbox and main gear, it is this element that is responsible for transmitting all the increased torque to the wheel. Unlike conventional drives, stronger materials are used here, there are no hollow pipes. Larger diameter grenades (CV joints).


drive unit

In a rally, for example, even in spite of this, on a powerful front-wheel drive this is almost always a weak point requiring regular replacement of 300-500 km, the normal resource after which changes to new ones.

On cars with different drive lengths on the right and left (for example, frets, some Renault, etc.), constructions with an intermediate support and a shaft are used as on many foreign cars.

Limited slip differential (lock) and main pair

I'll try just without complicated technical details.


disk diff circuit

Conventional differential: if one wheel is on ice, the other on asphalt, it will slip with what is on the ice.

Here is a video that describes the principle of a conventional differential well and simply.

Limited slip differential: will transmit torque to the wheel standing on the asphalt.

The disc differential is capable of transferring more torque to the second wheel. Also, by changing the number of friction pairs and ramp angles, different work for acceleration and braking is provided. Thus, the adjustment of this unit affects the handling.

Disc limited slip differential improves acceleration and improves time on the track.

But its resource, before servicing, is not at all great, and also requires the use of special oils.

On an all-wheel drive car, there are up to 3 disc differentials.

Moreover, on advanced and expensive cars, an electronically controlled center differential. Which changes forces based on speed, transmission, engine torque, etc. This is a complex device with a customizable control program, and very often the key to a fast and comfortable, comfortable racing ride lies precisely in the area of ​​setting the program of this differential. It can radically change the behavior of a car.

As for the main pair, first of all it is a different gear ratio, like that of the gearbox. It is often shorter. To provide the best dynamics. In many sports, maximum speeds are not needed by anyone because the track does not allow them to be reached even close, so the main pair, like the gearbox, must provide the highest possible dynamics over the entire speed range.

Transmission. (Several types)

Automatic machines in the conventional sense (hydro AT) are used extremely rarely in motorsport, there are so-called DSG robots.

As I already wrote the task to provide dynamics, in many sports you can change gear ratios and select the optimal one for a specific track. The gear ratios are selected so that there are no failures and the engine is always driven in the desired speed range. The rider, in turn, is required to keep the engine in the operating range to get the most efficient acceleration. To transfer large moments, the gearbox housing is reinforced or changed.

Synchronized checkpoint.

It is used when it is forbidden by technical requirements and regulations to put something else, or when there is no financial opportunity to buy a sports gearbox. It is similar in principle to a civil gearbox with synchronizers, the only difference is that the gear ratios may differ. Most often helical.



The principle of operation is visible in the video

Cam gearbox.

This is a gearbox with an H-shaped circuit like a conventional one, but there are no synchronizers in it. Instead, cam clutches.


cam clutch

This allows you to shift faster and without using the clutch.

The cam gearbox is always spur gear in order to eliminate the arising axial shock loads.

This photo was taken when the Sadev checkpoint was taken apart on my RACE CAR


sadev is one of the leaders in the field of sports gearboxes

The principle of operation and explanation can be seen in this video.

Sequential Gearbox

This is a cam gearbox in which the shift mechanism has been modified so that the pilot only pulls the lever forward and backward. Forward is a downshift, backward upshift.


the difference is visible in the switching mechanism

Mysteriously, but for some reason, in many automatic transmissions with a manual shift mode, an illogical, reverse direction is used. For me it is a mystery covered in fog.

As a video illustration, the work of a pilot with such a checkpoint. In order not to release the gas pedal during acceleration at all, a limit switch is added to the lever thanks to the signal from which the engine momentarily cuts off the ignition, allowing the clutch to operate without load.

Where permitted, steering wheel shifting is added to this.

I won't talk about robots like DSG and PDK, but they are sometimes used in circuit races. However, the top is still considered a sequential gearbox with petals.



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