Scraping noise when driving slow can be very irritating, most importantly, indicate something sinister is happening to the vehicle. Leaving it unchecked could prove fatal for the car; that’s why you should find out what is causing the unsettling noise.
Fortunately, we know the common causes of the scraping noise when you drive slowly, which we’ll share with you. Then we’ll suggest a few ways you can fix these causes whenever you encounter them.
JUMP TO TOPIC
- 1 What Causes Scraping Noise When Driving Slowly?
- 1.1 Damaged Brake Pads
- 1.2 Damaged Wheel Bearings from Excess Friction
- 1.3 Malfunctioning Car Brake Calipers
- 1.4 A Slack Engine Belt Unable to Hold the Pulleys
- 1.5 A Malfunctioning Transmission
- 1.6 Inadequate Lubrication for Components of the Brake System
- 1.7 Worn Brake Rotors Grinding Against Brake Pads
- 1.8 Worn-Out CV Joints on Older Cars
- 1.9 A Slack Timing Chain
- 2 How To Fix Scraping Noise When Driving Slowly
- 3 Conclusion
What Causes Scraping Noise When Driving Slowly?
The cause of a scraping noise when you drive slowly means the wheel bearings, the brake pads, or the rotors could be faulty. It could also mean the brake calipers are damaged, the engine belt is loose, the transmission is failing, or the braking system lacks lubrication.
Damaged Brake Pads
The brake pads ensure the car vehicle slows down when the corresponding pedal is pressed. It does this by pressing against the wheel and generating frictional force that opposes the car’s motion. The brake pads are prone to wear and tear due to the enormous stress placed on them during braking.
However, there are some brake pads that don’t fall into any of these categories, making them dangerous to use. Thus, we recommend that you only purchase certified brake pads from accredited sales agents.
Damaged Wheel Bearings from Excess Friction
Wheel bearings hold the wheels firmly to the vehicle and keep the tire rotating. Without the bearings, the wheels won’t be able to overcome the frictional force and move the vehicle. However, that same force, together with the weight of the vehicle and its occupants, causes damage to the bearings. The process is hastened when the vehicle carries passengers/cargo beyond its capacity.
The more frictional force exerted on the bearings, the faster they wear and begin to produce a scraping noise when turning left at low speed. The bearings are lubricated to enhance their work. However, they lose their lubrication over time, and the bearings begin to grind against some components. This grinding act produces an irritating rotational noise at low speeds.
Malfunctioning Car Brake Calipers
Malfunctioning brake calipers produce a squeaking sound as they grind against other metallic parts of the brake system. The brake calipers press against the wheel rotors, using frictional force to slow down the vehicle. This action causes the calipers to wear, leading to a scraping noise from front wheel when driving.
Sometimes, malfunctioning brake calipers could get stuck, and when they do, they produce a scraping sound as they meet with the rotors.
A Slack Engine Belt Unable to Hold the Pulleys
The engine belt, (or serpentine belt), provides power to some components of the car, like the alternator, power steering pump and air conditioning. The work of the belt is aided by pulleys around which the belt is wound. These pulleys, in turn, are held in place by the belt.
The belt needs to be very tight to work, but it could lose its “tightness” as time goes on. When that happens, the loose engine belt is unable to hold the pulleys in place properly, and you hear grinding noises. The noise is audible, especially when driving below 20 mph.
A Malfunctioning Transmission
The transmission is one of the areas you’ll least suspect if you hear your car making grinding noises. However, it could be the main suspect. The transmission might be making noise because it lacks lubrication or the gears are malfunctioning.
If you hear any scraping sound from the transmission when you use the lower gears, know that the gears are somehow damaged and need to be replaced. You can check the transmission fluid and top it up if you suspect it is the source of the grinding noise.
However, if the issue is triggered by the lower gears, then you’ll have to replace them. We’ll advise that you let a professional examine the failing transmission to determine the exact component causing the problem.
Inadequate Lubrication for Components of the Brake System
The brake system relies on lubrication to function properly. The system itself uses hydraulic pressure provided by the brake fluid to slow vehicles down. Also, some components at the backside of the brake need lubrication to complete their work. Without adequate lubrication, these components scratch each other, resulting in brake problems.
One such component is the brake caliper which requires a brake caliper lube to prevent it from scratching the caliper piston. Also, the caliper pins need lubrication, or else they’ll scrape both sides of the brake calipers, generating that grinding noise. Remember, the brake system plays a major role in slowing down the vehicle; that’s why you hear these noises when you slow down.
Worn Brake Rotors Grinding Against Brake Pads
When you push down on the brake pedal, hydraulic pressure forces the brake pads against the rotors, which creates friction. The frictional force slows down the vehicle but generates a great amount of heat. Due to the heavy pressure from the brake pads, the rotors are subject to wear, and you can do little about it. The brake rotors have a smooth surface and are visible through the tires.
However, when they begin to wear, you’ll see horizontal lines develop on the surface. When the brake pads press against these horizontal lines, it results in a scraping noise while driving stops when braking.
Worn-Out CV Joints on Older Cars
When you hear a scraping noise while you negotiate a turn or rubbing noise from front wheel when driving slowly, the chief suspect is a bad CV joint. The constant velocity (CV) joints connect the transmission to the wheels and axles. They also ensure that the shaft rotates freely and help in keeping the car stable. The joints have lubricated bearings that help them function efficiently.
However, these bearings tend to lose their lubrication over time, causing a scraping noise when the joints are engaged. Worn CV joints are more common in older front-wheel drive vehicles than newer ones.
A Slack Timing Chain
A timing chain synchronizes the movement of the camshaft and the crankshaft to move the wheels. It also allows the cylinders to produce enough power to propel the car. Thus, when it becomes loose, it’ll cause a grinding noise in the wheels, especially when you drive slowly. Worst still, the camshaft and crankshaft won’t be in sync, which spells danger for the engine.
A scraping noise coming from the engine isn’t to be joked with. Thus, attend to it immediately to protect the engine from damage.
How To Fix Scraping Noise When Driving Slowly
To fix the scraping noise when driving slowly will depend on the cause of the sound. You can replace a few of the parts by yourself, such as the brake pads and rotors if you have the experience. Other parts, like the timing chain, must be done by an expert.
How To Fix Worn Brakes Pad Yourself
First, you’ll need thick hand gloves, a lug wrench, jack and jack stands, C Clamp, a plastic tie, a wrench and a Turkey baster. Also, have a can of brake fluid and a new set of brake pads near you. While the car is still grounded, lose the lug nuts on the wheel, then raise the car with the jack and place the jack stands under it. Next, remove the slider bolts and inspect the thickness of each pad to determine whether they need replacement.
Remove the old retaining clips (clips that hold the brake pads) and replace them with new ones. New brake pads come with retaining clips, which you can just snap in place. Once the new retaining clips are installed, apply grease on them to prevent them from squeaking. Now, slide the brake pads into the calipers, and push back the pistons with the help of the C-clamp.
Check the brake fluid level and use the turkey baster to suck some out if it looks like it’s going to overflow. If it isn’t about to overflow, leave it at that, as the fluid will go down naturally when the brake pads begin to wear. Reposition the caliper and return the slider bolts to complete the process. Repeat the same process with the remaining wheels until all is done.
Replacing Damaged Bearings
Park the vehicle on a flat surface and secure the tires with a wheel chock. The next step is to lose the lug nuts and then raise the wheels with a jack. Now that the wheels are up, unscrew the nuts and remove the wheels. Remove the brake caliper and tie them with a cord to prevent them from damage.
Next, grip the dust cover with your caliper and tap it with a hammer to remove it. You’ll see the cotter pin, which you can remove with pliers and unscrew the castle nut. Remove the rotor with your bare hands or a rubber mallet when it’s stuck. Next, unscrew all the nuts that hold the hub in place and then dismantle the hub to get access to the bearings.
Break the races with a hammer and chisel and wipe the inside of the bearing assembly and knuckle with some rags. Now, install new races, as the old ones will be of no use to you. Next, install the new bearings and apply lots of grease to them. Remember to replace the parts you removed in reverse order.
This article has discussed the causes of the rhythmic scraping noise when driving and has suggested a few ways to solve them:
Here are the highlights of the major points raised in case you missed them:
- Squeaking noises from vehicles have several root causes, including damaged brake pads, rotors, brake calipers and bad wheel bearings.
- A lack of adequate lubricants and fluids in the braking system can cause the metallic parts to rub against each other and produce unsettling noises.
- You should suspect a broken CV joint when you hear scraping noises from under the car, but if the noise is from the transmission, then the gears may be faulty.
- A slack serpentine belt won’t properly hold the pulleys in place and will result in a screeching noise, while a loose timing belt won’t sync the camshaft and crankshaft well.
- Fixing damaged parts like a broken CV joint, timing chain and the serpentine belt is tricky and will require the help of an expert.
However, you can fix the ball bearings, brake calipers and brake pads by carefully following the instructions mentioned above. Also, ensure you get the right replacement parts to fix the issue and lubricate the metallic parts well to prevent future grinding noise while driving but not brakes applied.
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