Spar in a car: where it is, what it looks like and why it is needed

The spar is one of the key elements of the car body, which many drivers have heard about, but not everyone knows exactly where it is located and what it looks like. This part plays a critical role in ensuring body rigidity and occupant safety in the event of an accident. Without side members, a modern car simply would not be able to withstand the loads of driving, not to mention an accident.

In this article we will take a closer look at where exactly the side members are located in different types of cars, how they are designed and why their damage can become a serious problem. You will learn how to check the condition of these elements yourself and what to do if they are deformed. We will also answer frequently asked questions about the repair and replacement of side members, taking into account the characteristics of popular car brands.

What is a spar and why is it needed in a car?

Spar (from French longeron - “longitudinal beam”) is the main supporting structure of the body, which absorbs and distributes loads when the vehicle moves. In fact, this is the skeleton of the car on which all other elements are attached: engine, suspension, body panels. Without side members, the car would lose strength and become dangerous to operate.

Main functions of spars:

• 🔧 Ensuring body rigidity — prevent the car from “twisting” when turning or on uneven roads
• 🚗 Energy absorption upon impact — deform in a controlled manner, protecting the interior from destruction
• 🔄 Fastening key units — the engine, gearbox, and suspension elements are fixed on them
• ⚖️ Weight distribution — evenly transfer the load from the vehicle’s weight to the wheels

Most modern cars use pair scheme — two spars (left and right), located symmetrically along the body. However, in some models (for example, in Mercedes-Benz S-Class or Volvo XC90) additional transverse beams can be used to strengthen the structure.

Where is the side member located in a passenger car: location diagram

In passenger cars, the side members are always located in the lower part of the body, parallel to the longitudinal axis of the machine. They can be seen if you look under the bottom or remove the front fender. Traditionally, there are three key areas for their location:

1. Front - from the radiator to the front wheels (here the side members are often integrated with front bumper and engine mounts)
2. Central part — under the cabin, along the sills (the strongest and hardest area)
3. Rear — from the rear wheels to the trunk (may be shorter or absent in hatchbacks)

The location of the side members can be most clearly seen in car frame (for SUVs) or on monocoque body (for most cars). For example, in Toyota Camry or Volkswagen Passat the side members run almost the entire length of the body, and in Renault Logan they are shorter and end in the rear seat area.

Body type	Location of side members	Features
Sedan	From front bumper to trunk	Long, with reinforcement in the central part
Hatchback	From front bumper to rear axle	Shorter than sedans, often integrated with rear arches
SUV	Bumper to bumper (full size)	Often collapsible, with additional amplifiers
Minivan	Full length, with additional cross members	Reinforced for increased load (many passengers)

To understand exactly where the spars are located in your car model, you can:

• 🔍 Look under the car (they are visible as two parallel beams)
• 📖 View the body diagram in repair manual (for example, for Ford Focus or Hyundai Solaris)
• 💻 Find a 3D model of the body on the Internet (many manufacturers publish such diagrams)

What a spar looks like: photos and design features

Externally, the spar is hollow metal beam U-shaped, box-shaped or tubular section. Its shape and metal thickness depend on the class of the car and the loads it must withstand. For example:

• 🚘 B small city cars (type Kia Picanto) spars are thinner and lighter
• 🚙 B business class sedans (Audi A6, BMW 5-series) they are more massive, with additional stiffening ribs
• 🚛 B SUVs (Toyota Land Cruiser, Nissan Patrol) spars are often dismountable, with bolted connections

The photographs below show typical spars:

(There would be photographs of side members of different cars here, but in text format we will describe their visual features.)

• 📸 Front spar: usually curved upward to go around the wheel arch, often coated with an anti-corrosion compound
• 📸 Central section: straight, with holes for mounting suspension and levers
• 📸 Rear spar: may be shorter or absent (in hatchbacks), often integrated with the bumper

The material used also varies:

• 🔩 Steel - the most common option (cheap, durable, but heavy)
• 🔲 Aluminum - used in premium cars (Jaguar, Tesla) for weight loss
• 🔳 Composites - in sports cars (McLaren, Ferrari) for maximum strength with minimum weight

Why are the spars made hollow?

The hollow design allows you to combine high bending strength with minimal weight. In the event of a frontal impact, such a spar collapses in a controlled manner, absorbing energy and protecting the interior. A solid beam would be heavier and would not provide the same level of safety.

How to check a spar for damage: signs and diagnosis

Side member damage is one of the most serious body problems that can make a car unsafe for use even with seemingly minor deformations. Main causes of damage:

• 🚗 Road accident (even mild impacts to the bumper can deform the side member)
• 💥 Hitting a curb or hole (especially dangerous for front side members)
• 🔧 Corrosion (rust “eats” the metal from the inside, weakening the structure)
• 🔄 Poor quality repairs (for example, after replacing a bumper without checking the geometry)

Signs that something is wrong with the spar:

⚠️ Attention: If after an accident the doors no longer close tightly or gaps appear between the body panels, this is a sure sign of displacement of the side members. Operating such a vehicle is dangerous!

• 🔧 Uneven gaps between the hood, fenders and doors
• 🚗 Pulling the car to the side when driving in a straight line (even after wheel alignment)
• 🔊 Creaks and knocks in the front part of the body when driving over uneven surfaces
• 📏 Visible dents or rust on the spar (visible when viewed from below)

How to check the spar yourself:

For accurate diagnosis use:

• 📐 Laser stand — checks body geometry with millimeter accuracy
• 🔍 Endoscope — allows you to inspect the internal cavities of the spar for corrosion
• 📊 Computer diagnostics — analyzes data from suspension sensors (if any)

What to do if the spar is bent: repair or replacement?

If diagnostics show deformation of the spar, you have two options: renovation (edit) or replacement. The choice depends on the extent of damage, type of car and budget.

Repair (editing) of the spar possible if:

• 🔧 Deformation does not exceed 30-50 mm (depending on the car model)
• 🔩 The metal has no cracks or tears
• 🔄 The geometry of the body is not broken critically (checked at the stand)

Editing is carried out on slipway - a special machine that pulls out metal with millimeter precision. Modern services use laser stands (for example, Car-O-Liner or Celette), which guarantee restoration of factory geometry.

Replacing the spar required if:

• 🚗 The deformation exceeds 50 mm or the metal is torn
• 🔥 The spar is rusted through (especially dangerous for safety)
• 💥 The car has been in a serious accident (even if outwardly the side member looks intact)

Replacement is a more expensive but also more reliable option. On most modern cars, the side members are welded to the body, so they are cut off and new ones are welded. In some models (for example, Toyota Hilux or Ford Ranger) the spars are bolted on, making replacement easy.

Type of repair	Cost (from)	Deadlines	When to choose
Editing on the slipway	15 000 — 50 000 ₽	1-3 days	Slight deformation, no cracks
Partial replacement (welding of insert)	30 000 — 80 000 ₽	3-5 days	Local damage (for example, after hitting the bumper)
Complete replacement of the spar	50 000 — 150 000 ₽	5-10 days	Severe deformation, rust, metal tears

⚠️ Attention: After repairing or replacing the spar, it is imperative to do body geometry check and wheel alignment. Otherwise, the car will behave unpredictably on the road, and the tires will wear out over several thousand kilometers.

Is it possible to drive with a bent side member? Security implications

Many drivers ask the question: “Is it possible to drive if the side member is slightly bent?” The answer is clear - no, and here's why:

Even if the deformation seems minor, it leads to:

• 🚗 Impaired controllability — the car can “steer” to the side, especially at high speed
• 🛑 Incorrect operation of the suspension — shock absorbers and levers wear out 2-3 times faster
• 💥 Deterioration of passive safety - in the next accident, the side member will not be able to properly absorb the impact energy
• 🔧 Problems with other systems - for example, the radiator or air conditioner may move

Moreover, in most countries a car with a deformed side member will not pass technical inspection. In Russia, according to GOST R 51709-2001 and Technical regulations of the Customs Union, body elements that affect safety (and the spar is just that) must be in good working order.

What happens if you ignore the problem:

Consequences of driving with a bent side member

After 10-20 thousand km, uneven wear of the tires and suspension will begin. After 30-50 thousand km, cracks may appear in the places where the spar is welded to the body. In the event of a new accident, the deformed side member will not be able to properly distribute the load, which increases the risk of injury to passengers.

If you bought a car with a damaged history and discovered damage to the side member, it is better to start repairs right away. In the long run, this will cost less than eliminating the consequences of driving a crooked car.

Spars in different brands of cars: design features

The design of the side members can vary significantly depending on the make and model of the vehicle. Let's look at the features of the most popular brands:

1. Domestic cars (Lada, UAZ)

• 🚗 Spars are simpler in design, often made of thicker steel (3-4 mm)
• 🔧 Easier to repair (cheaper parts and labor)
• ⚠️ More often suffer from corrosion (weak anti-corrosion treatment)

For example, in Lada Vesta the side members are integrated with the subframe, which makes them difficult to replace, but increases body rigidity.

2. Japanese cars (Toyota, Honda, Nissan)

• 🔩 Spars often have a variable cross-section (thicker at the front)
• 🛡️ Well protected from corrosion (galvanized, anti-gravel coating)
• 🔧 In some models (for example, Toyota Land Cruiser 200) collapsible side members

3. German cars (Volkswagen, BMW, Mercedes-Benz)

• 📐 Precise geometry, complex shape of side members (requires high-precision equipment for repairs)
• 💰 Expensive spare parts and work (for example, replacing a spar with BMW 5-series may cost 100,000+ ₽)
• 🔬 Aluminum or high-strength steel is often used

4. American cars (Ford, Chevrolet)

• 🚛 The spars are more massive, designed for high loads (especially in pickups)
• 🔧 Often bolted on for easy replacement
• ⚠️ In some models (for example, Ford F-150) use aluminum spars

5. Korean cars (Hyundai, Kia)

• 🔄 Unified designs (many spars are interchangeable within the platform)
• 💰 Average prices for repairs (cheaper than German ones, but more expensive than domestic ones)
• 🛡️ Good corrosion resistance (especially in new models)

💡

Before purchasing a used car, be sure to check the side members for signs of repair or corrosion. Even a slight deformation can indicate a serious accident in the past.

FAQ: Frequently asked questions about side members in a car

Is it possible to straighten the spar yourself?

No, it is impossible to straighten the spar yourself without special equipment. For this you need slipway (body straightening stand) and laser measuring systems. Attempts to straighten the spar with a jack or hammer will lead to even greater deformation and disruption of the body geometry. In addition, after unprofessional editing, the metal loses its strength, which makes the car dangerous to operate.

How much does it cost to replace a side member on popular models?

The cost depends on the make of the car and the type of repair:

• Lada Granta/Vesta: 20,000 - 40,000 ₽ (editing) / 40,000 - 70,000 ₽ (replacement)
• Toyota Camry: 50,000 - 90,000 ₽ (editing) / 80,000 - 120,000 ₽ (replacement)
• Volkswagen Passat: 60,000 - 100,000 ₽ (editing) / 100,000 - 150,000 ₽ (replacement)
• BMW 3/5-series: 80,000 - 150,000 ₽ (editing) / 150,000 - 250,000 ₽ (replacement)

Prices are per one spar excluding painting and additional work.

How to protect side members from corrosion?

To prevent rusting of the side members, you should:

1. Wash the underbody of the car regularly (especially in winter, after treating roads with reagents).
2. Apply anti-corrosion compounds (for example, Molykote, Dinitrol or Tectyl) on the side members and their joints.
3. Check integrity protective covers (plastic or rubber linings covering the side members from below).
4. Process the internal cavities of the side members wax corrosion inhibitors (for example, Noxudol or Waxoyl).

On new cars, side members often already have anti-corrosion treatment at the factory, but this needs to be updated every 2-3 years.

What is a “spar platform” and how does it differ from a regular one?

Spar platform (or frame with side members) is a type of body structure where the side members are the main load-bearing elements and all other panels are attached to them. This scheme is typical for:

• 🚛 Trucks (for example, GAZelle, ZIL)
• 🚙 SUVs (for example, Toyota Land Cruiser 70, Nissan Patrol)
• 🚜 Pickups (for example, Ford Ranger, Chevrolet Silverado)

Differences from a conventional monocoque body:

• ✅ Great strength - withstands high loads
• ✅ Maintainability — spars can be replaced separately from the body
• ❌ More weight — the frame adds 100-300 kg to the weight of the car
• ❌ Less comfort — vibrations are absorbed worse (if additional dampers are not provided)

Can the spar burst from rust?

Yes, the spar can completely rust through, especially if the car was operated in high humidity conditions or did not have anti-corrosion protection. Critical signs:

• 🔍 Visible holes in the metal of the spar
• 💥 Crunch or crackle when driving over uneven surfaces (indicates destruction of the metal structure)
• 🚗 Sagging body parts (for example, front fender)

If the spar is rusted through, it definitely needs to be replaced - no amount of welding or patching will restore strength. Operating such a car is extremely dangerous, since in the event of an accident the body will not be able to protect passengers.