When it comes to car suspension, many drivers think of shock absorbers, springs or levers - but not everyone immediately thinks of steering knuckle. Meanwhile, this unit plays a key role in control: it is the one that connects the wheel with the steering mechanism and ensures its rotation. If you hear a knocking sound when turning the steering wheel, notice play or uneven tire wear, the problem may lie here.
But how do you find the steering knuckle if you have never looked deep into the suspension? Where is it located - front, back or both sides? And why can its design differ even on the same car model depending on the type of drive? In this guide we will look at exact locations steering knuckle on the front and rear axles, we will show it in photos and diagrams, and also explain how to identify it among other suspension parts.
Important: the information is relevant for most passenger cars - from VAZ 2107 up to Toyota Camry, but there are nuances for all-wheel drive and rear-wheel drive models. If your car is one of the latter, pay attention to the separate section of the article.
What is a steering knuckle and why is it needed?
Steering knuckle (sometimes called trunnion or wheel axle) is a suspension part that performs three key functions:
- 🔄 Turn the wheel — connects the steering rod to the wheel, allowing it to turn left and right.
- 🚗 Wheel mount — a hub, brake disc and bearing are installed on the fist.
- 🔧 Connection with suspension — through ball joints or levers it is connected to the shock absorber and spring.
Without a steering knuckle, the car simply would not be able to maneuver. And if it fails (for example, due to bearing wear or a crack in the metal), this leads to:
- ⚠️ Steering wheel play — the car is “driving” to the side.
- 🔊 Knocks when turning - especially on rough roads.
- 🛞 Uneven tire wear - due to violation of the wheel alignment angles.
On most modern cars, the steering knuckle is made of high-strength steel or aluminum alloys (for example, BMW 5 Series or Audi A4). SUVs and trucks may have reinforced versions with additional stiffening ribs.
Where is the steering knuckle located: front axle
On front-wheel drive and all-wheel drive in cars the steering knuckle is always located on the front axle on both sides - right and left. It's easy to find if you know the key landmarks:
- Open the hood and look at the front wheel. The steering knuckle is the part to which it is attached wheel hub (the part where the disc mounting bolts or nuts are screwed on).
- If you remove the wheel, you will see the brake disc and behind it - a massive metal element with holes for the ball joints and steering rod. This is a fist.
- On cars with suspension McPherson (for example, VW Golf, Renault Logan) the fist is attached to the shock absorber strut and lower control arm. On multi-link suspension (like Mercedes E-Class) - to two or three levers.
Visually, the steering knuckle of the front axle resembles fork with two “horns” - Ball joints are installed in them. In the center there is a hole for the wheel bearing. A steering tip (rod) usually sticks out from the side, connected to the rack.
To find your fist faster, turn the steering wheel all the way to the side - this will move it and become more noticeable.
| Suspension type | Where to look for a fist | Examples of cars |
|---|---|---|
| McPherson | Attaches to the strut and lower arm | Lada Vesta, Skoda Octavia, Hyundai Solaris |
| Multi-link | Connects with 2-3 arms | Audi A6, BMW 3 Series, Lexus RX |
| Double wishbone | Between the upper and lower arms | Ford Focus, Mazda 3, Toyota Corolla |
⚠️ Attention: On some vehicles (for example, Nissan Qashqai or Mitsubishi Outlander) the steering knuckle can be integrated with the hub into a single unit. In this case, replacement is more expensive, since you have to buy a complete assembly.
Steering knuckle on the rear axle: is there one?
On most rear wheel drive and all-wheel drive car steering knuckle on the rear axle missing. Instead it is used beam or bridge, where the wheels are rigidly fixed and do not turn. However, there are important exceptions:
- 🔄 Rear-wheel drive cars with independent suspension (for example, BMW 5 Series (E39), Mercedes W124) - there may be steering knuckles, but they are not connected to the steering, but serve only to secure the wheel.
- 🚙 All-wheel drive crossovers and SUVs (for example, Toyota Land Cruiser 200, Nissan Patrol) - knuckles are sometimes installed on the rear axle to improve off-road handling.
- 🏎️ Sports cars (for example, Porsche 911) - can have a steerable rear axle with knuckles for better dynamics.
As a rule, if there is a steering knuckle on the rear axle, it looks simpler than the front - no mounts for tie rods, but with similar points for the bearing and arms. To find it:
- Raise the car on a lift or jack and remove the rear wheel.
- Look behind the brake disc - if there is a massive metal part with mounts for the levers, this is the fist.
- On most sedans and hatchbacks you will see a knuckle instead of a beam (straight pipe) or bridge - in this case there is no fist.
How to distinguish a steering knuckle from a hub?
The hub is the smaller piece that screws into the knuckle and holds the bearing. The fist is a large element to which the levers and steering rod are attached. On many cars the hub is removable, but the knuckle is not.
What does the steering knuckle look like: photo and diagram
In order not to confuse the steering knuckle with other suspension parts, pay attention to its characteristic features:
- 🔧 Form - resembles the letter “U” or “Y” with holes for fastenings.
- 🔩 Fastenings:
- From above - to the shock absorber or upper control arm.
- From below - to the lower arm through the ball joint.
- On the side - to the steering rod (on the front axle).
- 🛠️ Material - usually black or gray metal (steel/aluminum) with stiffeners.
Below is a diagram of a typical suspension knuckle McPherson:
In the photo (if there was one) you would see:
- Hole for the wheel bearing (in the center).
- Two “horns” for ball joints (top and bottom).
- Mount for tie rod (side).
- Stiffening ribs to strengthen the structure.
On some vehicles (for example, Subaru Impreza or Mitsubishi Lancer) the fist can be asymmetrical - the right and left ones differ in shape. When replacing, it is important not to mix up the sides!
How to check the steering knuckle for malfunctions
If you suspect the problem is in the steering knuckle, follow these steps to diagnose:
Raise the car on a jack and remove the wheel | Rock the wheel in a vertical plane (play indicates wear of the bearing or ball bearings) | Check the fist for cracks and deformations | Inspect the tie rod and ball joint mounts for play | Spin the wheel - squeaking or jamming will indicate problems with the bearing-->
Typical symptoms of a malfunction:
- 🔊 Knocking sound when turning the steering wheel - often caused by play in ball joints or a crack in the knuckle.
- 🌀 Vibration on the steering wheel - may indicate deformation of the knuckle or bearing wear.
- 🛞 Uneven tire wear - if the fist is bent, the wheel is at the wrong angle.
- 🚗 Pulling the car to the side - often associated with wheel alignment problems due to a deformed knuckle.
Pay special attention cracks - even a small crack can lead to the fist being torn off while moving! Inspect it with a flashlight, especially around the welds and arm attachments.
⚠️ Attention: If you hear a metallic grinding sound when braking, it may not be a fist, but brake caliper or disk. But if the sound appears precisely when turning the steering wheel, the fist or ball joint is to blame.
When do you need to replace the steering knuckle?
The steering knuckle must be replaced in the following cases:
| Reason for replacement | Consequences of ignoring | Repair cost (approx.) |
|---|---|---|
| Crack or deformation | Fist detachment while moving, loss of control | From 3,000 to 15,000 ₽ (depending on the model) |
| Bearing seat wear | Wheel play, vibration, accelerated tire wear | From 5,000 to 20,000 ₽ (with bearing replacement) |
| Damage to ball joint threads | Impossibility of reliable fastening, backlash | From 4,000 to 12,000 ₽ |
| Corrosion that eats away metal | Weakening of the structure, risk of breakage | From 2,500 to 10,000 ₽ |
It is better to trust the replacement of the fist to professionals, as it requires:
- 🔧 Special puller for ball joints.
- 🔩 Torque wrench for proper tightening of bolts.
- 📐 After replacement, a procedure is required wheel alignment.
On some vehicles (for example, Ford Focus 3 or Kia Rio) the fist comes complete with a hub and bearing - this simplifies replacement, but increases the cost of the spare part.
If the fist is deformed after an accident, it must be replaced - even if the car is driving. A deformed fist changes the wheel alignment angles, which leads to uneven tire wear and poor handling.
How to remove and install the steering knuckle: brief instructions
If you decide to replace the knuckle yourself, follow this algorithm (using the example of a front-wheel drive car with suspension McPherson):
- Raise the car on a jack, remove the wheel and disconnect
brake caliper(hang it on a wire to avoid damaging the hose). - Unscrew the hub nut (you will need a socket on
30-36 mmand a long lever). - Disconnect
tie rod endfrom the fist (use a puller). - Unscrew the bolts securing the knuckle to
shock absorber strutandlower arm. - Remove the fist along with the hub. If the hub is removable, separate it.
- Install the new fist in the reverse order, observing the tightening torques (indicated in the manual).
Important details:
- 🔧 On some machines (for example, Renault Duster) will have to be removed
drive shaft (grenade)to remove the fist. - 🔩 Knuckle mounting bolts often stick - use WD-40 or similar penetrating lubricant.
- 📋 After installing a new fist necessarily do
wheel alignment.
⚠️ Attention: If you are replacing a knuckle on one side, it is recommended to check the condition of the knuckle on the opposite side - they wear about the same. On some models (for example, Volkswagen Passat B6) fists are sold in pairs only.
FAQ: Frequently asked questions about the steering knuckle
Is it possible to drive with a cracked steering knuckle?
No! Even a small crack can cause the fist to burst while moving, especially when making a sharp turn or hitting an obstacle. The consequences are loss of control and a serious accident. If a crack is found, replace the part immediately.
How to distinguish the knock of the steering knuckle from the knock of the ball joint?
The knock of the ball joint is usually heard when driving over bumps (for example, speed bumps) and disappears on a flat road. Fist knocking occurs more often when turning the steering wheel and may be accompanied by vibration. For an accurate diagnosis, you need to raise the car and check the play.
How much does it cost to replace a steering knuckle at a service center?
The cost depends on the car model and region:
- Budget cars (Lada, Renault, Kia) - from 3,000 to 8,000 rubles per side.
- Middle class (Toyota Camry, Volkswagen Passat) - from 8,000 to 15,000 rubles.
- Premium and SUVs (BMW X5, Mercedes GLE) - from 15,000 to 30,000 rubles.
The price includes labor (1.5–3 hours) and spare parts. The wheel bearing and ball joints are usually paid separately.
Is it possible to restore the steering knuckle (for example, weld a crack)?
Theoretically it is possible, but highly not recommended. The fist experiences enormous loads, and even a high-quality seam may not withstand the impact of hitting a hole. The exception is rare cases where the fist is made of forged steel (for example, on some Jeep or Land Rover), but even here the risk remains. It's better to replace it with a new one.
Is it necessary to do a wheel alignment after replacing the steering knuckle?
Yes, necessarily! Even if you installed the cam in the same position as the old one, the wheel alignment angles will change. Without adjustment, the car will “pull” to the side, and the tires will begin to wear unevenly. The cost of wheel alignment is from 1,000 to 2,500 rubles.