Why Does the Front Wheel Disc Heat?
Modern cars, including production models, are quite powerful and high-speed, so the smooth operation of the braking system is a priority. When the car’s brake discs get warm, it is one of the signs of malfunction in the braking system.
In order to understand this problem, it is necessary to understand the principle of disc brakes, to consider the types of discs, the basic requirements for them and the causes of their heating, as well as to understand how to recognize overheating and to what consequences it may lead.
Front and rear brakes of this type are installed on many modern cars because of their reliability, efficiency and ease of maintenance. The principle of their work is simple – the caliper piston presses on one of the pads, the second is compressed automatically by its body thanks to movable guides. Both pads squeeze the brake disc on both sides, and then, due to friction, the movement is slowed down.
Since all friction converts kinetic energy into thermal energy, the discs and pads begin to warm up during braking. Sometimes to such an extent that after hard braking there is smoke coming from them. To minimize this phenomenon and manufacturers have begun to produce different types of these parts.
How to avoid overheating
To avoid overheating brakes make the main contribution, of course, manufacturers, using the most thermally conductive materials for their manufacture and developing vented design, in which the brake discs consist of two parts, with built-in between a special fan.
The design of the brake disc itself, which is capable of self-cleaning from dirt and ventilated by the oncoming flow, is considered one of the most successful design inventions.
In order to prevent overheating of the brakes during operation, you must first of all keep the brake system in working order, and to do this you must regularly check:
- the level of brake fluid in the master cylinder reservoir;
- the thickness of the brake disc;
- wear of the brake pads.
Standard discs of many car brands are made of cast iron.
This is due to its good frictional properties and inexpensive cost. But these parts made of cast iron have a number of drawbacks. With frequent braking they start to get very hot up to several hundred degrees, which can cause the emergence of fumes when the friction layer of the pads melts and warping themselves.
And if more water will get on their overheated up to such degree surface, they can elementary crack.
To reduce overheating they started to produce ventilated discs with honed hollows inside.
But this has not cardinally changed their features. Therefore, manufacturers are concerned about their replacement and began production of new perforated and stratified products, made of steel alloys. In the first, additional ventilation provides a lot of small holes around the diameter.
And the latter have grooves turned on both sides.
After replacing the standard, perforated or slotted discs, they start to warm up much less. And anyone who has swapped the standard cast-iron brake components for perforated or perforated ones immediately feels the difference.
Warning! In no case it is impossible to make vent holes in standard cast iron brake discs by yourself! They are not designed for this and can simply crack!
Buckled or damaged brake discs
In addition to the above causes, you can also add driving on the handbrake, sticking pads. This problem causes loss of geometry, and then, even if the pads are in good working order, the parts have to be in constant contact with each other, resulting in excessive overheating of the harness.
More serious is the destruction of the brake disc. The problem occurs when water gets on the overheated part. And this is very common. For example, when the car hits a puddle. Here there is a sharp temperature drop and the formation of spider cracks on the disk or its deformation occurs.
A simple inspection will help to identify the problem. The part is not repairable, it must be replaced.
Basic requirements for discs
For safety reasons, discs must meet the basic requirements that apply to them:
- Stability of performance when heated.
- Non-responsiveness to thermal shock.
- Resistance to adhesion (low adhesion threshold).
- Sufficiently high thermal conductivity of the material from which it is made.
- High coefficient of friction and strength.
If the product does not meet these requirements, the possibility of getting the car in an accident significantly increases.
The brake system of the car
It is based on the same principle as bicycle brakes, improved and modified. In this construction the pads are pressed to the brake discs by hydraulic action. The machine stops due to the frictional force known to everyone since school days. Hence, another piece of knowledge – a fair amount of heat is always released during friction.
So, when the brakes work, the pads can get hot.
Brake discs for cars are made of special alloys, alloyed steel or cast iron, now there are also made of carbon or ceramic. These materials perfectly retain their properties when heated even up to 1000 degrees, which will never happen during braking.
It should be noted that if the front brake discs are heated, you should not panic, a certain level of heat the driver will feel, being in the vicinity. Perceived heat is caused, it would seem, completely imperceptible to the driver in the city conditions. Many have brought their actions to automatism – in traffic jams, even in an unloaded road, brake, clutch, gas – all levers are pressed and released an infinite number of times, what then to say about the heated discs? They simply do not have time to cool down in such a strenuous mode of operation.
Strong heating of the brake discs may indicate a malfunction of the car
Another thing, if the front brake discs are strongly heated, this can indicate malfunctions of various origins. Breakdowns will become known not only by overheated wheels, but also will appear:
- vibration when braking;
- jerking motion;
- presence of strange sounds, squeaks;
- disc disc color changes (this sign indicates that the metal was heated to the limit temperature parameters, you can distinguish several thresholds, when the steel is yellowing, turning blue or black).
Causes of heating
Many motorists wonder why the brake discs heat up. It seems that when inspected at the service station the wheels rotate freely, without catching anything, but after driving it is impossible to touch this part of the brakes. There are several reasons for this phenomenon:
- Severely worn discs and pads. This can happen when they should have been changed, but did not do it in time. After all, when the thickness of the metal decreases, it is easier to warp when overheated.
- The owner put in new low-quality pads.
- After replacement, poor-quality brake fluid was poured into the brake system.
- The disc itself is deformed. It happens when water gets on the heated metal.
- A disc also gets hotter during an aggressive drive. In which the constant change of acceleration by braking does not allow the elements of the brakes to cool.
- If the car is provided with drum-type rear brakes, the front brake discs are mainly heated during braking.
Front wheel disc warming causes
August 20th, 2020 admin Any vehicle, especially such as a high-speed passenger car, which carries a potential threat to the life and health of both the driver and others, cannot be imagined without emergency stopping devices.
Such mechanism is a brake system and its maintenance in working condition, first of all for your own safety is a direct duty of the owner of “iron horse”.
How to recognize and what becomes the reason of overheating?
It is not always possible to understand that discs overheat badly, excluding the cases when there is smoke when braking. Although their heating over 200 degrees should already cause a question for every car owner – why are brake disks warmer than they should be? Indirect symptoms may help to understand it:
- After soft pressure on the brake pedal, the pads strongly block the brakes and do not move away from the discs, even at the end of braking, although they should do it. You may cause the car to skid. This happens when the guides jam. It is always necessary to lubricate the caliper guides when the pads are replaced.
- Jerks, knocks, vibrations, light smoke in the wheel area after braking can also indicate problems caused by faulty brake discs.
- Increased fuel consumption is another indicator that the brake system is faulty and blocked.
- After replacing the pads, it is impossible to get the necessary speed and light smoke appears when driving. This can occur when the brake pads are installed with a thicker than necessary friction layer.
If such signals appear, you should immediately inspect the condition of the pads and discs and replace defective parts.
How to prevent overheating?
To prevent such situations, it is necessary to adhere to some recommendations.
Ways to prevent overheating
- Passing regular maintenance is not another opportunity for the over-insurers to rob you, but the recommendations of scientists obtained as a result of numerous studies. You shouldn’t ignore rules created years ago for your own safety.
- Aggressive driving is the enemy of your car. Intense sharp braking leads to metal heating (discs get hotter much faster than they cool down). As a result, the operation of the braking system is disrupted.
- The level of brake fluid in the system is another factor that affects the performance of the brakes. Have the fluid level checked regularly.
- Don’t forget to replace the brake discs . Each manufacturer indicates on their product mileage, after passing which it is necessary to carry out the replacement. As an exception, in some cases, the wear of discs and pads can occur much earlier (depending on operating conditions).
- Chasing the economy is not the best option. Buying cheap low-quality products, you put yourself in danger. There is no need to save on your own safety.
- Avoid “self-medication”. Replacement of elements of the braking system is better to leave to professionals. Only professionals have the right to be responsible for the quality of performed work.
- Use the services of car wash. Try to avoid washing the car immediately after driving, when the elements of the braking system are still hot. In this case, you need to wait a little while for the discs to cool down. A seemingly simple rule, but it will save brake discs from possible damage caused by sudden temperature changes.
Important! Sometimes problems with overheating occur just after you have replaced the brake pads yourself. In the wrong hands, remedies can cause an accident.
How to understand that the brake disc is warming up
Discs are one of the key components of a vehicle’s braking system. They are usually made of cast iron and function with the help of a clamping mechanism, with which the pads are also in a duet. The latter come into contact with the discs when braking, slowing down the vehicle. At the same time, the discs become warm. In some cases, they overheat. A driver with solid experience determines this without difficulty. Beginners often do not pay attention to the “signals” that the car gives when the brake discs overheat.
Among the first symptoms of this problem:
- The appearance of sounds resembling a squeaking or squeaking;
- the car does not pick up speed when driving in “neutral” from the mountain
- sudden increase in fuel consumption;
- rapid wear of the pads.
If you find at least one of these signs, check the temperature in the area of the discs to be sure of your suspicions. To do this, drive 300-400 meters, braking periodically. Stop and put your hand near the discs. Only do not touch, otherwise you will get a strong burn. Their normal temperature should be about 200-300oC. When overheated it increases, so you will feel the strong heat from the disks even at a distance.
If you do not trust your feelings, use a special device for measuring the temperature. You can buy it in an auto store.
Experienced drivers can determine the constant overheating without devices. It is enough to look at the discs, the color of which will tell you a lot. Thus, at a constant temperature of 150-300oC, the steel turns yellow. Disks look like rusty and it scares many motorists. In fact, it is a normal reaction of steel to temperature increase. A 200-300oC in the brake system is normal, so you do not need to worry. Blue or black color of disks should alert. They become so at “chronic” temperature rise up to 400-500oC.
With a suspicion of discs overheating, do not be lazy to diagnose the braking system at a trusted auto service center. Your life and the lives of other road users literally depend on its serviceability.
How dangerous is overheated disc brakes
A heated disc loses its main function. Pads are sliding on its surface, not catching. As a result, the car becomes uncontrollable due to lack of proper braking.
In addition, excessive temperature deforms the disc. If even small drops of water hit it, it can become cracked and even crumble.
Malfunctions: Causes of heated brake discs
Excessive heating, over 200 degrees, indicates a malfunction due to several common causes:
- Disk integrity failure or deformation;
- lack of sufficient brake fluid level;
- Poor-quality or severely worn pads;
- drum brake pads on the rear wheels – in this case you should not be surprised why the front ones are heating – they take the maximum load on themselves, unloading the rear axle.
It is worth paying attention to the pads
How does malfunction appear?
Trouble, the consequence of which is intensive heating of the brake disc, manifests itself with a characteristic metallic creaking from the friction of the metals between themselves. As a rule, any one brake pad begins to jam, so the brake disc overheats on one side.
Warping of the front discs, since they most often suffer from such a defect, is accompanied, in addition to overheating, and beating on the steering wheel while driving.
Severe wear of the pads and discs (below the minimum allowable values) manifests itself in a deterioration of their braking qualities and an increase in the distance required to stop the car. In addition, it may be accompanied by a creaking from the contact of the metal part of the pad with the shoulder of the disc and a decrease in the level of brake fluid in the reservoir of the master cylinder.
10 reasons why the wheels of the car may be warm
In the vast majority of cases, the search for the cause of why the wheel hub is heating, begins when a characteristic burning smell is felt in the cabin or traces of burning are visible on the disc. Also the desire to touch the disk arises, if the car during braking moves sideways, the rolling is deteriorated, or after stopping a crackling is heard from the wheel. Pedal vibrations during braking can also be a symptom of overheated wheels.
In practice, there are several reasons for such a malfunction. At the same time, not only the brakes can be to blame. This article briefly describes the most common causes, why the wheels warm up, how to diagnose the problem, and what ways it can be eliminated.
Reason #1. Intense braking
To begin with, it is probably worth mentioning that, the heating of wheel rims is a quite natural phenomenon. It occurs due to the friction of the brake pads against the disc (drum) surface while the car is stopped. The energy of the car’s movement is converted into heat, which is transmitted to the wheels, which is the cause of their heating.
There are several factors that affect the degree to which wheels with a fully functioning braking system are heated.
- Firstly, the ambient air temperature. In the summer heat, even on a standing car, the wheels on the sun may heat up so much that it is impossible to keep a hand on their surface. This factor should be taken into consideration.
- Secondly, the degree of wheel heating is influenced by the intensity of braking. If, for example, to move in the city from traffic lights to traffic lights, or in a traffic jam, where brakes are used time after time, overheating of wheels is quite natural.
- Thirdly, during intensive braking the heating of the wheels is influenced by the speed of the car. Thus, when driving on the highway, discs and rubbing parts of brakes are blown by oncoming air, as a result of which they are cooled more effectively. When driving in the city, the speed is usually low, so the brakes are only heated, but not forcedly cooled in any way.
To rule out the described causes of overheating wheels, just check their temperature after driving at normal speed in cool weather and stopping without applying the brakes. If there is no scorching sun, no frequent or prolonged braking, the wheel rims should be cool or slightly warm on a serviceable car.
Reason #2. Driving with a handbrake
Contrary to popular opinion, it is not only the beginners who make such a mistake. Experienced drivers also quite often forget to remove the car from the handbrake before driving. Unfortunately, such inattention can cost much more than simple overheating of rear wheel disks.
If you drive on the handbrake long enough, the brake discs can warp irrevocably due to excessive overheating. This will further cause the wheels to heat up, as the pads will constantly be in contact with the disc regardless of the position of the brake pedal.
Reason #3. Jammed brake cylinder pistons
When the brake pedal is depressed, excessive pressure is created in the system due to the fluid, which moves the pistons in the brake cylinders. This presses the pads against the brake discs and brings the vehicle to a stop.
Since the brake cylinders are subjected to harsh operating conditions, dust, dirt, water and other factors can cause them to begin to seize up. The most common problem is that the brake cylinder piston is unable to return to its original position on its own due to the vacuum created in the system. Accordingly, the brake pads also move away from the disc incompletely, and their friction continues all the time.
Diagnosing such a problem is quite simple. The unit is disassembled, inspected for mechanical defects, lubricated and sealed. The latter should be paid special attention, since the ingress of dust, moisture and dirt between the tightly fitted to each other piston and cylinder will certainly lead to jamming. As a rule, tightness of the assembly is ensured by rubber caps. Therefore, if they are damaged or lose elasticity, this is most likely to be the reason of disc overheating.
Reason #4. Air in brake system
Principle of brake system operation is based on the transmission of force through the brake fluid. If there is air in it, this inevitably leads to the fact that the pistons of brake cylinders cannot return to their initial position after braking. Even one small air bubble can cause so-called “no braking”. In other words, the brake pads always remain pressed against the discs, albeit slightly, which understandably causes excessive heating of all adjacent metal parts.
Most often such a defect is observed after the repair of the brake system, which was accompanied by complete or partial drainage / refill of the fluid. Such operations must be followed by pumping of the system, the purpose of which is just to remove the air trapped inside. If this procedure was done incorrectly or hastily, it can lead not only to the heating of discs. Air in the system may cause slack in the brake pedal, as well as reduced braking efficiency.
There is no way to detect air in the system. Therefore, if there is a suspicion of its presence, the only thing left is to re-pump according to the rules prescribed by the car manufacturer. As a rule, it is necessary to do it after an independent repair, or after visiting a service station with unqualified personnel.
Reason No. 5. A stuck brake pad.
A stuck pad is one of the most common causes of overheated discs. This defect can occur for a variety of reasons. In particular, the brake pads stick to the discs due to poor quality, size discrepancy, uneven wear, trapped dirt, and the described defects of the brake cylinders.
The breakage is diagnosed quite simply. To do this, just hang the car on an elevator or jack, and manually rotate the wheels with the handbrake removed and in neutral gear. If any of the wheels has a stuck brake pad, it will not rotate by inertia. If the overheated wheel turns by inertia at least by one and a half or two revolutions after a slight hand effort transmitted to it, the cause is not in the stuck pads.
Reason #6. Worn or damaged brake disc
Brake discs lead due to overheating, which occurs due to the reasons described above. Including, it can get warped after driving on the handbrake or because of a stuck pad. When this happens, the disc loses its geometry, and even serviceable pads are constantly in contact with it, causing excessive overheating of the whole harness.
A more critical problem is the partial destruction of the brake disc. This happens, as a rule, if water gets on the overheated part. Since this happens very often with a car wheel (when hitting a puddle), the disc as a result of a sharp temperature drop is covered with a web of cracks, or it gets puckered or deformed.
Detecting a defective brake disc is sometimes possible with a simple visual inspection. This part cannot be repaired, that is why the problem will disappear only after replacement.
Reason #7. Overstrained hub bearing
This, and the following possible reasons why the wheels on the car warm up, are not related to the faults of the braking system. That is why they are paid attention to them last, which is fundamentally wrong.
If the hub bearing was tightened with excessive force during repair, the result is that it will overheat instantly, even at low driving speeds. Later on, all the grease in the bearing will evaporate due to the high temperature, and the friction heat will increase many times over.
All this may cause heating of the wheel rims. If you continue operating the car with a similar defect, then after a few tens of kilometers it will lead to total failure of the bearing. It will simply jam and collapse.
To check if the hub bearings are not overtightened, carry out all the same operations as in step 5. The manually unscrewed wheel should not stop immediately. If it does not rotate by inertia, it indicates either an overtightened or worn hub bearing if the brakes are functioning properly. If it has not failed in such operation, the problem is solved by tightening the nut with the correct torque.
Reason #8. Lack of grease in the hub bearing
There can be several reasons for the lack of grease in the hub bearings. One is described above – the lubricant simply burns out and evaporates when the nut is overtightened. In addition, the grease can be washed out by water due to damaged dust covers, or it can be exhausted after years of improper maintenance. As a result, the part overheats and the heat from it is transferred to the wheel rims.
Unfortunately, if hub bearings have been operated without lubrication for some time, the problem may be corrected only by full replacement with a new one.
Reason #9. Hub Bearing Wear
Excessive hub bearing wear also increases the parasitic friction force, which causes the entire unit to overheat. Unserviceable bearings can be identified by several signs. First, worn bearings noticeably hum during movement. Secondly, the heat discussed here can also indicate wear. Third, if the hub bearings are damaged, the wheel will visibly wobble across the axis of the car when it is lifted or jacked.
Reason #10. Caliper guides jamming
The last possible cause of the overheated wheels on the car, which should not be forgotten, is the jamming of the caliper guides. This occurs both due to wear of parts, and because of dirt, metal corrosion, mechanical damage (hitting a pothole, etc.) Identify these problems is easy enough without going to a specialist. Scuffing of caliper guides is detected on an unsuspended wheel without a disc.
In many cases, fix the breakdown can be simple cleaning and washing the node, for example, in kerosene.
The bottom line is .
As can be seen from the above, there may be several reasons for excessive overheating of the wheel rims. To find and eliminate the fault, it is necessary, first of all, to check the elements of the brake system. If the brakes are serviceable, the cause of heating can be a worn, unlubricated or trivial overtightened hub bearing.