There are many technical terms in the automotive industry that are often abbreviated or replaced with acronyms. When it comes to the type of transmission, many drivers wonder: what is rear-wheel drive called in a professional environment? The answer is simple: in technical documentation and among engineers this system is called RWD (Rear-Wheel Drive). It was this scheme that was considered classic for most passenger cars for a long time.
Understanding the operating principles of such a transmission is necessary not only for general development, but also for choosing the right car for your tasks. Historically, it was RWD dominated the market in the early and mid-20th century, providing optimal weight distribution and handling. Today we will look at all the nuances of this design.
Knowing how the torque transmission system works to the rear wheels will help you better feel the car's behavior on the road. This is especially true in winter or during emergency maneuvering. Next, we will take a detailed look at the device, advantages and disadvantages, and also examine common misconceptions.
Terminology and basic designations
You will rarely find a Russian-language description of the drive type in a car’s technical passport or in spare parts catalogs. The global standard dictates the use of Latin abbreviations. Main name - RWD. This marking clearly indicates that it is the rear axle wheels that are rotated by the engine. There is also the term FR (Front-engine, Rear-wheel drive), which specifies that the engine is located in the front.
It is important not to confuse the classic layout with a rear-engine layout, where the engine is located at the rear. In the latter case, the RR marking is used. However, in everyday life, when asking “what is rear-wheel drive called,” users usually mean the classic front-engine design. Used to indicate all-wheel drive AWD or 4WD, which fundamentally changes the driving dynamics.
In technical documentation you can also find the designation “cardan drive” as a key element of the system. It is the driveshaft that transmits power from the gearbox to the rear differential. Understanding these terms will help you communicate more competently with service station technicians and more accurately formulate problems when diagnosing.
⚠️ Attention: When purchasing winter tires, be sure to consider the type of drive. For RWD, the load on the rear axle is higher, which requires special attention to the tread condition at the rear.
Modern electronic systems often disguise the characteristics of the drive by adding simulated locking or wheel braking. However, the mechanical basis remains the same. Knowing the basic terminology allows you to resist marketing gimmicks and understand the actual design of your vehicle.
Design features of the RWD system
The classic rear-wheel drive scheme involves dividing the car into two functional parts: power and suspension. The engine, clutch and gearbox are usually located at the front of the body. Torque is transmitted to the rear axle through a long metal shaft, which is popularly called a “cardan”.
The key element of the entire system is gearbox (or differential) located on the rear axle. It not only transfers rotation to the wheels, but also allows them to rotate at different speeds when cornering. Without this mechanism, the car would be impossible to turn normally, and the tires would wear out within a few kilometers.
Unlike front-wheel drive cars, where the gearbox is combined with the main gear into a single unit (transmission), in RWD these units are distributed throughout the body. This creates some challenges for engineers when designing the cabin, as the driveshaft runs under the floor to form a distinctive central tunnel.
Why does the driveshaft vibrate?
The cardan shaft has a high rotation speed and length, so crosses and elastic couplings (guilbo) are used to compensate for vibrations and change operating angles. If you hear a hum or feel vibration, the problem is often a shaft imbalance or worn crosspieces.
The design requires a strong rear suspension capable of supporting the weight of the gearbox and the transmitted forces. Often such cars use a dependent suspension (axle) or a complex multi-link design. This makes the rear of the car look more massive compared to its front-wheel drive counterparts.
Benefits of rear-wheel drive for the driver
Why do many car enthusiasts still prefer RWD? The main advantage lies in the weight distribution and the nature of acceleration. During intense acceleration, the vehicle's weight is redistributed to the rear axle, which increases the traction of the drive wheels with the road. This allows the engine power to be realized more efficiently, especially on dry asphalt.
The handling of a rear-wheel drive car is considered more predictable and “honest”. The front wheels are responsible only for steering, without being distracted by the transmission of traction. This gives more precise feedback through the steering wheel and allows for tighter cornering since the front wheels don't "spin" under load.
- 🚀 The best acceleration dynamics: Weight is shifted rearward, improving traction on the drive wheels.
- 🔄 No twisting of the steering wheel: the front wheels are free from traction forces, the steering wheel does not break out of your hands during acceleration.
- 🅿️ Convenient parking: smaller turning radius due to the fact that the front wheels do not have drive joints.
- 🛠️ Maintainability: transmission units are spaced apart, making them easier to access during maintenance.
In addition, rear-wheel drive allows for vehicles with more advanced suspension geometry at the front. Not having to place drive shafts there gives engineers more freedom to optimize the kinematics, which has a positive effect on comfort and stability.
Rear-wheel drive provides a more balanced distribution of tasks between the axles: the front wheels steer, the rear wheels push.
Disadvantages and difficulties of operation
Despite the many advantages, the RWD scheme also has its disadvantages that cannot be ignored. The main one is the complexity and cost of the design. The presence of a driveshaft, a separate gearbox and additional hinges increases the weight of the vehicle and the number of components that can fail.
In winter conditions, rear-wheel drive often behaves more nervously than front-wheel drive. When hitting ice or slush, the rear axle tends to skid (oversteer). For an inexperienced driver, this can be an unpleasant surprise, requiring instant reaction and correct stabilization actions.
| Comparison parameter | Rear-wheel drive (RWD) | Front wheel drive (FWD) |
|---|---|---|
| Engine location | Front (usually) | Front transverse |
| Skidding behavior | Skidding (requires counter-steering) | Demolition (easier to control) |
| Patency | Below (on slippery) | Higher (weight above drive wheels) |
| Service cost | Higher (more nodes) | Lower (more compact) |
It is also worth noting the loss of usable space in the cabin. The central tunnel through which the driveshaft passes often interferes with the middle rear seat passenger. In addition, the presence of a rear gearbox can create additional noise when driving at high speeds if it is poorly insulated.
Comparison with front-wheel drive and all-wheel drive
To finally understand what rear-wheel drive is called and how it differs from its competitors, we need to draw parallels. Front wheel drive (FWD) dominates the mass segment due to its compactness and low cost. In this scheme, the engine and transmission are assembled into one unit, which frees up space in the cabin and trunk.
All-wheel drive (AWD or 4WD) combines the advantages of both schemes, transmitting traction to all four wheels. However, this is achieved at the cost of significantly complicating the design and increasing fuel consumption. Rear-wheel drive remains the golden mean for those who value balance and handling, but are not willing to overpay for the complexity of all-wheel drive.
In racing and sports driving, rear-wheel drive is valued for its ability to control the vehicle's trajectory not only with the steering wheel, but also with the gas. This allows you to perform controlled drifts, which is almost impossible to do with front-wheel drive. Front-wheel drive in extreme conditions is prone to drift of the front axle, when the car stops listening to the steering wheel and continues to move straight.
In terms of economy, FWD beats RWD due to lower weight and no energy loss in the long driveshaft. However, modern materials and technologies make it possible to minimize these losses, making rear-wheel drive quite competitive even in the executive sedan segment, where comfort and smoothness come first.
Driving features and winter operation
Driving a RWD vehicle requires certain skills, especially in winter. The main feature is the high tendency of the rear axle to skid when suddenly releasing the gas or adding traction on a slippery surface. The driver must always be ready to operate the steering wheel and pedals.
When starting off on ice, a rear-wheel drive vehicle may slip faster than a front-wheel drive vehicle, since the weight of the engine does not put pressure on the drive wheels. Therefore, in winter on RWD it is highly desirable to have good winter tires and, possibly, additional cargo in the trunk to improve traction.
- ❄️ Pulling away: try to start driving from second gear to avoid sudden jerking and slipping.
- 🛑 Braking: On slippery roads, avoid sudden braking when turning, as this may spin the car.
- 🔄 Skid correction: when the rear part begins to skid, you need to smoothly turn the steering wheel in the direction of the skid and add gas.
⚠️ Attention: Never fully depress the clutch when skidding on rear wheel drive, unless you are a professional. This can result in complete loss of control and a 180-degree spin.
However, many drivers choose RWD for its “driving” nature. The car becomes an extension of the driver’s hands, allowing you to feel every nuance of the road surface. With the right approach and good tires, winter operation does not cause serious problems even in harsh climatic conditions.
☑️ Checking RWD before winter
Frequently asked questions (FAQ)
Is it true that rear wheel drive is always better for drifting?
Yes, this statement is true. Rear-wheel drive allows the rear axle to break traction with the road independently of the front, which is the basis of drifting. On front-wheel drive, drifting is only possible using special techniques (handbrake drift), but it is less stable and controllable.
Can a rear wheel drive vehicle be towed with the front wheels raised?
No, this is strictly prohibited. If you lift the front wheels, the rear wheels will remain on the ground and spin the driveshaft and gearbox. Since the engine is not running, the pump does not provide lubrication, which will lead to rapid destruction of the gearbox. Towing can only be done with the rear axle fully raised or using a tow truck.
Why do road bumps feel more pronounced on rear-wheel drive?
This is due to the design of the rear suspension and the presence of a heavy gearbox, which is often attached directly to the suspension components. Any impacts are transmitted to the body more clearly than in schemes where there are no heavy rotating mechanisms at the rear. However, modern multi-link suspensions reduce this effect to a minimum.
What is the name for BMW's all-wheel drive?
BMW's all-wheel drive system is called xDrive. It is based on a classic rear-wheel drive, but can redistribute torque to the front axle if necessary. RWD remains the basic option for most BMW models.