Direct installation of the electric motor into the hub begins with dismantling the standard wheel and checking the free space in the wheel arch to accommodate the increased diameter motor-wheels. Before lifting the body on a jack, you must make sure that the selected engine model will physically fit into the place of the standard drive without modifying the suspension or body parts. If the gap between the brake caliper and the inside of the disc is critically small, you will need to install spacers or replace the calipers with more compact analogues.
The process requires precise alignment, since even minimal axle misalignment will lead to body vibrations at high speeds and premature wear of the hub bearings. Unlike factory electric vehicles, where the cooling and balancing system is designed by engineers, the integration requires manual check of disc runout after each assembly step. Ignoring this step can lead to the destruction of fasteners when reaching cruising speed.
Selecting the type of motor wheel and calculating power
The first step in planning a conversion is to determine the type of engine that will serve as the traction unit. There are two main options on the market: geared and gearless (direct drive) models. Geared versions are usually smaller, lighter and have high torque at low speeds, which is ideal for city driving with frequent acceleration. However, the presence of gears introduces additional noise and requires regular replacement of the lubricant.
Gearless motor-wheels, on the contrary, have no moving mechanical joints inside the stator, which makes them virtually silent and durable. Their design allows for the function of energy recovery during braking, returning charge to the battery. The disadvantage of direct drive is often the presence of magnetic resistance (cogging), which is felt as resistance to the rotation of the wheel when the engine is turned off.
- 🔋 Geared models: high efficiency at low speeds, lighter weight, free wheeling.
- ⚙️ Direct drive models: possibility of recovery, no rubbing parts, larger diameter for better cooling.
- 📏 Dimensions: it is important to consider that the wheel motor is always thicker than a standard disk, which affects the car’s track.
When calculating power, the total weight of the vehicle must be taken into account. For a passenger car weighing about 1200 kg, the minimum total power should be at least 10-15 kW for confident movement in city traffic. Using a motor that is too weak will lead to overheating and rapid failure of the winding insulation.
Preparation of technical base and tools
High-quality installation is impossible without specialized tools and preliminary preparation of seats. The main attention should be paid to the condition of the hub assembly and brake system, since increased dynamic loads will require ideal operation of all mechanisms. Before starting work, the vehicle must be securely secured on a level surface.
For installation, you will need a torque wrench to tighten the hub nuts to the nearest Newton meter, since excessive force can deform the motor axis, and weak force can cause the wheel to rotate. You also need a kit for working with electricians: calibrated crimping pliers, high-quality heat-shrinkable tubing and a multimeter for checking circuits.
⚠️ Attention: Before starting any work on the high-voltage part, make sure that the battery is disconnected from the on-board network. Incorrect polarity or short circuit may cause permanent damage to the controller and personal injury.
It is important to prepare places for mounting the controller and battery compartment in advance. Controller, manager electric motor, generates a significant amount of heat, so it requires a metal platform for heat transfer or active cooling. The placement of these components must prevent the entry of water and dirt when driving on a wet road.
Mechanical installation process in the hub
Mechanical installation of a motor-wheel on a car requires removing the standard wheel and, in some cases, dismantling the brake caliper or replacing it with an adapted one. If the design of the motor-wheel involves fastening through spokes or a flange, it is necessary to strictly follow the bolt tightening pattern to avoid distortion of the disk. Often, installing a wider motor wheel requires the use of hub spacers.
During installation, it is important to check the gap between the rotor magnets and the stator windings (if an external rotor is used) or ensure that there is no friction on the internal components. Any extraneous friction indicates improper assembly or deformation of the axle. After installing the wheel on the car, it is necessary to check the free rotation and absence of play in the horizontal and vertical planes.
☑️ Mechanical installation checklist
Particular attention should be paid to protecting the electrical terminals of the wheel motor. The wires coming out of the axis must be reliably protected from chafing and moisture. For this purpose, reinforced hoses or special corrugated hoses are used, which are hermetically connected to the motor housing.
Electrical diagram and controller connection
The electrical part of the refurbishment is the most complex and responsible, requiring a deep understanding of the operating principles brushless motors. The controller must match the battery voltage and current characteristics of the wheel motor. A mismatch between the parameters will lead to either insufficient power or burnout of the controller’s power switches.
The connection diagram usually includes power phase wires (three thick wires), Hall sensor wires (five thin wires) and power lines. It is important to use wires with a cross-section corresponding to the maximum current consumption. For powerful systems (from 5 kW), the cross-section of copper wires should be at least 10-16 mm² to minimize voltage loss and heating.
| Parameter | Minimum value | Optimal value | Note |
|---|---|---|---|
| Battery voltage | 48 V | 72-96 V | Depends on speed |
| Controller current | 20 A | 40-60 A | For one wheel |
| Cable cross-section | 6 mm² | 16 mm² | Copper, stranded |
| fuse | 30 A | 60-80 A | Fast acting |
The Hall sensors must be connected in strict accordance with the color coding of the controller. An incorrect connection will result in jerky operation, humming of the motor, or complete system inoperability. Some modern controllers have a function for auto-detection of phase order, which simplifies configuration, but you should not rely on it completely.
The nuances of soldering high-voltage connections
To connect power wires, use refractory solder and be sure to insulate the soldering areas with heat shrink and an adhesive layer. Regular electrical tape can melt when the wire heats up under load.>
To control the rotation speed, you need a potentiometer (gas pedal), which supplies a signal from 0.8 to 4 volts to the controller. It is also recommended to include an emergency shutdown system (Kill Switch) in the circuit, which will turn off the power to the controller in emergency situations.
System setup and first launch
The first start of the system should be carried out with the car body raised, when the wheels do not touch the ground. This will allow you to safely check the direction of rotation, the operation of the sensors and the absence of overheating of the components. When power is applied, there should be no sparking in the contacts, and rotation should be smooth and silent.
If the wheel motor twitches or makes an intermittent hum, you need to check the connection of the phase wires and Hall sensors. It is often necessary to change the phase connection order (for example, swap the yellow and green wires) to synchronize the operation of the controller and the motor. Modern programmers allow you to adjust the advance angle and current strength through the computer interface.
⚠️ Attention: Do not start the engine under load (on the ground) until all connections are fully checked. A sudden start may result in (loss of) vehicle control or damage to the transmission.
After a successful weight test, perform a low speed road test. Check the operation of the brake system, as the weight of the motor-wheel increases the unsprung mass, which can change the braking dynamics and the behavior of the suspension on uneven surfaces.
Legal aspects and operational safety
Installing an electric motor on a car is a change in the design of the vehicle, which requires mandatory registration with the relevant authorities and obtaining a certificate of conformity. Operation of an unregistered converted vehicle is prohibited and entails penalties, as well as problems when passing a technical inspection.
Operational safety directly depends on the quality of the components and assembly used. High-voltage DC systems present an electrical hazard, especially in humid environments. All connections must be sealed and cables protected from mechanical damage.
Regular maintenance includes checking the tightness of fasteners, the condition of wire insulation and the heating temperature of the motor-wheel after trips. The appearance of extraneous noise or vibration should be a signal for immediate diagnosis.
Frequently asked questions (FAQ)
Do I need to change the brake system when installing a wheel motor?
Yes, replacement is often required, since the wheel motor has increased dimensions and may not coincide with the standard caliper. In addition, the increased weight of the wheel requires more effective braking.
How much range can you get with one wheel motor?
The range depends on the battery capacity and driving style. For city driving on one wheel motor with a power of 5-10 kW with a battery of 10 kWh, the real reserve will be about 50-80 km.
Is it possible to make all-wheel drive by installing two wheel motors?
Yes, this is possible, but it requires the installation of two controllers (or one dual-motor), synchronization of their operation and a much more powerful battery.
How does a wheel motor affect a car's suspension?
An increase in unsprung mass negatively affects the comfort and life of the suspension. It is recommended to strengthen the suspension elements or use stiffer springs and shock absorbers.
Do I need a special license to drive such a car?
If, after the conversion, the vehicle remains in Category B (up to 400 kg curb weight for electric cars in some jurisdictions or up to certain power ratings), a Category B license is sufficient. However, the status of the vehicle must be changed in the documents.