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

Spars in Volkswagen Passat B6 or Toyota Camry are often damaged in a frontal impact, but their location depends on the body type. In most passenger cars, the side members pass front under the hood — these are two longitudinal beams connecting the front bumper to the interior. They are hidden under plastic covers and casing, so they can only be seen visually on a lift or after dismantling the protection. If after an accident the car “steers” to the side or cracks appear at the junction of the wing and hood, with a 90% probability it is the spar that is deformed.

In crossovers (for example, Hyundai Tucson or Kia Sportage) spars are often integrated into the subframe, and in pickup trucks (such as Ford Ranger) they can be part of the frame. Their main task is to absorb impact energy and maintain body geometry. At the same time rear side members (if they exist) are usually shorter and thinner, since the main load comes from the front. To accurately determine their location in your model, just look under the car: look for two parallel metal beams running from the bumper to the center of the body.

What is a spar and why is it called the “bone” of the car

Spar (from French longeron - "longitudinal beam") is body strength element, which acts as a frame. Unlike the cross members that connect the side members to each other, these beams run along the entire machine (or part of it) and absorb the main loads. They are often compared to ribs in the human body: if one is damaged, the entire “structure” suffers.

In modern cars, side members are made of high-strength steel or aluminum, and their shape is designed to programmable deformation upon impact. For example, in Mercedes-Benz E-Class The front side members have weld zones with “notches” that fold like an accordion, absorbing energy. In older cars (before the 2000s), the beams were straight and rigid, which often led to the transfer of shock to the passenger compartment.

• 🔧 Material: high-carbon steel (0.9–2.5 mm), aluminum (in the premium segment), composites (in racing cars).
• 📏 Length: from 50 cm (rear side members) to 2–3 meters (front side members in frame cars).
• 🔄 Shape: U-shaped, box-shaped, tubular or with complex relief for reinforcement.
• 💥 Function: load distribution in case of an accident, maintaining the geometry of the doors and roof.

Where exactly are the side members located: diagram for different body types

The location of the side members depends on type of supporting system car. In most passenger cars (sedans, hatchbacks) this front pair of beams, which are attached to the engine shield and go under the hood. But there are nuances:

Body type	Number of spars	Location	Examples of models
Sedan/hatchback	2 (front)	From the bumper to the engine shield, under the hood	VW Golf, Skoda Octavia, Renault Logan
Crossover/SUV	2–4 (front + rear)	The front ones are under the hood, the rear ones are under the trunk.	Toyota RAV4, Nissan Qashqai
Pickup/frame SUV	2 (integrated into frame)	Along the entire frame, from the bumper to the rear axle	Ford F-150, Toyota Hilux
Minivan	2–4 (front + middle)	Front - standard location, middle - under the interior floor	Volkswagen Multivan, Citroën SpaceTourer

In cars with monocoque body (90% of modern cars) side members are part of the power structure and are welded to the engine shield, pillars and sills. In frame cars (for example, UAZ Patriot or Jeep Wrangler) beams are individual elements of the frame on which the body is “put on.” To see the side members in the monocoque body, you will have to remove the plastic protection under the hood or look under the car from the wheel arches.

Where to look for spars in electric vehicles?

B Tesla Model 3 or Nissan Leaf The front side members are often integrated with the battery platform and have additional stiffening ribs to protect the battery. Their arrangement may differ from the traditional one - for example, the beams may be moved closer to the center of the machine to optimize weight.

How to check a spar for damage: 5 key signs

After an accident or a strong impact (for example, hitting a curb), the side member may bend or crack, even if the body looks intact. The following symptoms will help identify the problem:

1. Uneven gaps between hood and fenders. If the gap is wider on one side than the other, this is a sign that the spar is misaligned.
2. Difficulty closing doors or hood. A deformed beam changes the geometry of the body, causing the locking mechanisms to no longer match.
3. Uneven tire wear. A bent spar displaces the wheelbase, which leads to the rubber “eating” on one side.
4. Creaking or knocking noise when driving over uneven surfaces. Cracks in the metal or weakened welds produce characteristic sounds.
5. Pulling the car to the side. If you have to steer the steering wheel even on a flat road, check the wheel alignment and side members.

For an accurate diagnosis, use laser body geometry meter (available at the service station) or check the symmetry of key points using a tape measure. For example, the distance from the center of the front bumper to the side member on both sides must match to within a millimeter. In garage conditions you can use ruler — place it along the beam: if there is a gap of more than 1–2 mm, the spar is bent.

1. Remove the plastic protection under the hood (if equipped).

2. Inspect welds for cracks or rust.

3. Check the paint for blisters - this is a sign of hidden corrosion.

4. Run your hand along the beam: uneven or sharp edges indicate deformation.

5. Compare the location of the subframe mounts on both sides.

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What happens if you drive with a damaged spar: consequences

Ignoring the problem with the spar is fraught not only with deterioration in controllability, but also risk of body collapse in a repeat accident. Here are the problems that arise most often:

⚠️ Attention: If the side member is cracked in the area where the airbag mounts, the squib may deploy unpredictably in a crash (for example, sideways or delayed).

• 🚗 Violation of body geometry: doors stop closing, windows may jam, seals wear out 2-3 times faster.
• 🔧 Suspension problems: Displacement of the lever mounts or subframe leads to uneven wear of the silent blocks and ball joints.
• 💰 Reducing the cost of a car: a car with a “crooked” spar loses up to 30–40% of its price on the secondary market, even after repair.
• 🚨 Insurance Denial: if the accident occurred due to a defect in the side member (for example, a wheel fell off), the insurance company may find the owner at fault.

In frame cars (for example, Mitsubishi Pajero) a damaged spar can lead to frame distortion, which will cause transmission failure. In monocoque bodies (like Audi A4) a deformed beam often pulls the engine shield, which leads to problems with the electronics (for example, ABS sensors or airbags fail).

Is it possible to repair the spar or just replace it?

The issue of spar repair depends on degree of deformation and beam material. Shallow dents (up to 10–15 mm) can be straightened using slipway — a special stand that restores the geometry of the body to the nearest millimeter. However, there are cases when repair is impossible:

Type of damage	Is repair possible?	Cost (from)	Risks
Local dent (up to 20 mm)	Yes (straightening + amplifier)	15 000 ₽	Weakening of metal in the repair area
Crack or broken weld	Conditional (welding + strengthening)	25 000 ₽	Seam corrosion, risk of fracture in an accident
Deformation more than 30 mm	No (replacement only)	50 000 ₽	Violation of factory rigidity
Corrosion (through rust)	No	—	Risk of beam collapse upon impact

In a premium car (for example, BMW 5 Series or Volvo XC60) spars are often made from boron steel or aluminum that cannot be straightened using traditional methods. In such cases, manufacturers recommend complete replacement of the beam, since even microcracks reduce the strength by 40–60%. Alternative - installation reinforced inserts (patches), but this is a temporary solution that does not guarantee security.

Straightening on a slipway|Replacement with an original beam|Installation of a reinforced insert|I don’t know, depends on the price-->

How to protect side members from corrosion and damage

The spars rust from the inside, as condensation and dirt accumulate in the cavities of the beam. To extend their life, follow these recommendations:

• 🛠️ Anti-corrosion treatment: Apply once every 2–3 years ML oil or wax compositions through technological holes (their location is indicated in the manual).
• 🚿 Bottom sink: in winter, clean the side members from salt and reagents with a jet of water under pressure (but not closer than 30 cm, so as not to damage the protection).
• 🔩 Checking the fasteners: Once a year, tighten the bolts of the subframe and levers - loose connections create stress in the metal.
• 🛑 Curbs and holes: Avoid hitting the front bumper (even at low speed), as the side members are designed to collapse smoothly.

⚠️ Attention: Do not use on side members bitumen mastic - it clogs drainage holes and accelerates corrosion from the inside. Best option: paraffin inhibitors (for example, Tectyl or Dinitrol).

In cars older than 10 years (for example, VAZ 2110 or Daewoo Nexia) spars often rot where they are attached to the engine shield. To check this, tap the beam with a wooden hammer; a dull sound indicates internal corrosion. If rust is already visible from the outside, the spar can only be saved by complete replacement or cutting out the rotten area by welding (which will weaken the structure).

Frequently asked questions about spars

Is it possible to drive with a bent side member if the car does not “drive”?

No, even if the handling has not changed, the deformed beam disrupts the distribution of loads upon impact. In the next accident, the body may fold unpredictably, and the airbags may not work correctly. In addition, a bent spar creates stress in the welds, which accelerates corrosion.

How do I know if my car has side members at the rear?

Rear side members are found in crossovers, minivans and some sedans (e.g. Skoda Superb). To find them, look under the trunk: if you can see two parallel beams running from the rear bumper to the sills, that's them. In most hatchbacks (type Renault Megane) there are no rear side members - their role is played by reinforced sills.

How much does it cost to replace a spar at a service station?

The price depends on the car model and beam type:

• Budget cars (VW Polo, Kia Rio): 20,000–40,000 RUR for one side (with work).
• Middle class (Toyota Corolla, Ford Focus): 50 000–80 000 ₽.
• Premium (Audi A6, BMW 3 Series): RUB 100,000–200,000 (replacement with subframe is often required).
• Frame cars (Nissan Navara): 150,000–300,000 ₽ (frame welding required).

Original spars are 2–3 times more expensive than analogues, but guarantee factory strength.

Is it possible to straighten the spar yourself?

Self-straightening is possible only with minimal dents (up to 5–10 mm) and the presence hydraulic jack with stops. To do this:

1. Remove the plastic protection and trim.
2. Attach the stops to undamaged areas of the body.
3. Slowly press the jack onto the bent area, checking the gaps.
4. After straightening, check the geometry with a laser level.

Important: Without a slipway and experience in body work, you risk the body warping or weakening the welds.

How are spars different in electric vehicles?

In EV (for example, Tesla Model Y or Hyundai Ioniq 5) spars often perform two functions:

• Protection of the battery from breakdown upon impact.
• Weight distribution (beams are reinforced as the battery weighs 300–500 kg).

They are usually made from aluminum or composites, and are shaped to “flow around” the battery during a frontal collision. Repairing such side members costs 1.5–2 times more than that of an internal combustion engine car.