Introduction to the problem and diagnosis
Owners Skoda Octavia A5 often encounter a characteristic hum, which increases as the vehicle speed increases. This sound is often confused with tire noise or engine trouble, but in most cases the problem lies in wear. front wheel bearing. Ignoring this symptom can lead to wheel seizure or, even worse, hub destruction while driving.
On the platform PQ35, which is used in Octavia A5, the bearing is pressed into the steering knuckle and is a non-separable unit. This means that if play or noise occurs, a complete replacement of the unit is required, rather than repair. It is important to understand that on front-wheel drive versions Octavia A5 the bearing experiences enormous loads due to the transmission of torque through grenade (CV joint) directly through it.
Symptoms of malfunction and diagnostics of the unit
It is possible to determine that a bearing has failed using several clear criteria. The first and most obvious sign is a hum or howl that changes tone when you turn the steering wheel. If the sound becomes quieter when turning left, and louder when turning right, then the problem is in the bearing. left hubs, and vice versa.
The second important sign is the presence of play in the wheel. To check, you need to lift the car on a lift or jack, remove the wheel and rock it with your hands in a vertical plane (top-bottom). If you feel a knocking noise or movement of the hub relative to the knuckle, wheel bearing requires immediate replacement. It is also worth paying attention to the ABS sensor, which often fails due to the destruction of the magnetic ring inside the bearing.
- ๐ Constant hum depending on wheel speed
- ๐ Change in sound when turning the steering wheel in different directions
- ๐ ABS error on the dashboard (magnetic ring wear)
- ๐ค Sensible backlash of the hub when rocking the wheel
Required tools and spare parts
For a high-quality job you will need a specialized tool, as old methods of knocking the bearing with a hammer can damage the rotary fist. Octavia A5. You will definitely need a removable for hub nuts (a 30 mm rattle or a special key), a dynamometer key and a hydraulic press or mandrels to press the new node.
As for spare parts, the choice of manufacturer plays a critical role. The market is presented as original details. Skodaand quality analogues from brands SKF, FAG or NTN. Cheap Chinese fakes often donโt have a magnetic ring for ABS or quickly fail due to poor quality lubrication. Never skimp on a bearing, as jamming it at speed can be fatal.
Before starting work, make sure you have everything you need to dismantle the suspension. Also do not forget about consumables: brake fluid, lubricant for slats and a new nut of the hub, as the old one often deforms when unscrewed.
- ๐ ๏ธ Hub nut septor (30 mm or 36 mm depending on the year)
- ๐ง Hydraulic press or set of pressure mandrels
- ๐ Dynamometer key (required to tighten moments)
- ๐จ Balloon key, jack and car stands
- Original Skoda
- SKF/FAG
- Chinese equivalent
- I don't know
Step-by-step process of dismantling the old bearing
Start by unscrewing the hub nut. This should be done before you fully lift the car so that the wheel does not scroll. Use a powerful collar and possibly an extension for the lever, as the nut is tightened with a big moment. After that, lift the car, remove the wheel and dismantle the caliper, hanging it on the wire so as not to damage the brake hose.
Next, you need to unscrew the bolts of fastening the swivel fist to the lever and the shock rack. Be careful with ball supports and steering tip - they also need to be disconnected. Once the fist is freed, you will see a grenade. It must be removed from the hub, using a filmmaker or carefully poke the mount, trying not to damage the anther of the SRUS.
The most difficult step is the removal of the old bearing. Ideally, this is done by the press through a turning fist. If there is no press, you can use a removable for hub bearings. In no case do not try to knock the bearing through the inner ring - this will lead to the destruction of the rollers and damage to the internal clip, which will make it impossible to install a new node.
After removing the bearing, be sure to clean the seat in the swivel fist from rust and dirt. Use a metal brush and solvent. The surface must be perfectly smooth, otherwise new bearing It will be broken and will quickly break down. Check the condition of the hub of the wheel - it should not be bullies or production.
โ๏ธ Preparing for removal
Installation of a new unit and pressing
Installing a new bearing requires precision. The bearing must enter the rotary fist with the help of a press, relying strictly on the outer ring. If you press on the inner ring, you will damage the separator and rollers. Use special mandrels or an old bearing as a sling to distribute the force evenly.
Before pressing, apply a thin layer of lubricant to the seat in the fist. This will make installation easier and prevent corrosion. Press the new knot to the point until it sits in its place. After installation, make sure that the bearing is flat and has no distortions. Any deviation will result in rapid wear and noise.
Next, you need to install a hub inside the new bearing. This is also done through a press, resting on the inner ring of the bearing. After installing the hub, collect the suspension in reverse order. Donโt forget to install a new locking ring if it comes complete, and tighten all the bolts of the fist mounting carefully.
Pay special attention to the nut of the hub. It must be drawn with the exact moment specified by the manufacturer. Usually around 200 Nm plus the corner angle. Use the dynamometer key. After the puff, be sure to check that the wheel rotates freely without snagging.
Why not put pressure on the inner ring?
When pressing the hub or bearing, the pressure on the inner ring is transmitted through rollers to the outer clip. This causes microcracks and the destruction of the separator, which leads to premature failure of the node. Pressure is necessary only on the ring that enters the seat with tension.
Features of tightening and checking the work
After the suspension assembly, it is necessary to check the correctness of the installation. The rotation of the wheel should be smooth, without snacking and extraneous sounds. The steering must be clearly operated, without backlashes that may occur when the steering tips are installed incorrectly. Conduct a visual inspection of all connections for reliability.
Tightening of the wheel mount bolts is done on the ground when the car is lowered. Time of tightening of wheel bolts for Octavia A5 amounts to 120 Nm. Do not pull them over so as not to tear the thread, but also do not leave them too weak. After the first 50-100 km of run, it is recommended to check the tightening of all critical suspension units.
If you have an ABS lamp, donโt panic. Often the sensor is simply confused or requires adaptation. Try to drive a few kilometers in different modes. If the error does not disappear, it is possible that during the installation, the sensor wire or the magnetic ring of the bearing was damaged. In this case, a scanner will be required.
- โ The wheel rotates freely without noise.
- โ All bolts are tightened with a dynamometer key
- โ No backlashes in steering and suspension
- โ ABS lamp fails to burn or reset after test
The main mistake when replacing is incorrect pressing, when the force is transferred to the wrong ring of the bearing, which leads to its instant destruction.
Typical mistakes and advice from experts
Many craftsmen make the mistake of trying to replace only the bearing without replacing the hub if there is a production on it. You can't do that. The slab must be placed in the slab with a certain amount of pressure. If it's hanging around, the bearing will rattle. Also, do not neglect to replace the hub oelbone if it is damaged - this can lead to a leak of lubricant.
Another common problem is damage to the wiring of the ABS sensor when dismantling the fist. Be very careful when you put the wiring aside. A wire break will cause the ABS system to fail and the corresponding lamp on the dashboard will light up. It is better to check the integrity of the chain with a multimeter.
Do not forget about lubrication of ball supports and steering tips during assembly. If you do not grease the grenade slime before installation, it can jam when tightening the nut of the hub. Use a special lubricant for SRUS, not lithole or solidol, which can break down the anther rubber.
Before starting work, take a picture of the location of all the wires and hoses of the suspension. This will help you assemble the knot properly and remember to connect ABS sensors or brake temperature sensor wires, if any.
Table of moments of tightening for the Skoda Octavia A5
For the correct assembly of the suspension, it is necessary to observe the tightening moments specified by the manufacturer. Deviation from these values can lead to the destruction of the thread or weakening of the fastening during movement. Use only a working dynamometer key.
| Fastening element | Tightening torque (Nm) | Additionally |
|---|---|---|
| Hub nut (front) | 200 + 90ยฐ | Use a new nut |
| Wheel bolts | 120 | Tighten crosswise |
| Steering knuckle bolts to strut | 130 | Replace the bolts with new bolts |
| Rotating fist bolts to the lever | 110 | Wrapping with suspension under load |
| Steering nut | 30 + 90ยฐ | Protect the carvings from dirt |
โ ๏ธ Attention! Does the hub nut have a left thread? No, front-wheel drive. Octavia A5 The carving is standard (right), but the tightening moment is very large. Do not confuse the direction when unscrewing if you use a pneumatic tool.
โ ๏ธ Attention! Never use a shock screw to tighten the nut of the hub. This can lead to deformation of the bearing and violation of the geometry of the node. Use only a dynamometer key or a powerful corner control gate.
Conclusion and final recommendations
Replacing the front wheel bearing with Skoda Octavia A5 This is a task of medium complexity, requiring attention and the right tool. If you are not confident in your abilities or do not have a hydraulic press, it is better to entrust the work to professionals. Savings on quality parts or improper installation can result in re-repairs in the shortest possible time.
Remember that the safety of your car depends on the condition of the chassis. Regular diagnosis of the suspension and timely replacement of worn parts will help to avoid serious breakdowns in the way. After the replacement, be sure to test drive and check the operation of ABS and ESP systems.
How long does it take to replace a bearing?
On average, an experienced master replaces one front bearing takes 1.5 to 2.5 hours. If you use a press and have all the necessary detachers, the process can be accelerated. Beginners may need more time due to the need to find a tool and learn the nuances.
Is it possible to drive with a faulty bearing?
It's not recommended. Driving with back lift of the bearing can lead to its jamming, which is fraught with the destruction of the hub, damage to the brake system and even loss of control of the car. In addition, a worn bearing can damage the ABS sensor and wiring.
Do I need to do a wheel alignment after replacement?
Yes, after replacing the hub bearing, especially if the swivel fist was removed and the suspension geometry was broken, it is necessary to make a collapse-descend. This will ensure proper tire wear and stable vehicle behaviour on the road.
How to choose a quality bearing?
Give preference to proven brands: SKF, FAG, NTN, Timken or Skoda. Avoid cheap analogues of unknown origin, as they often have defective lubrication or ring misalignment. Check for a magnetic ring for ABS.