Knocking Sound When Braking Rear: 9 Proven Causes & Measures

If you’re driving your car and you hear a knocking sound when braking rear, do not look down on the signal. The problem may be riskier than you assume.

It’s essential to check it out as soon as possible to ensure that your brakes are in good working order.

A few different things can cause a knocking sound from the rear brakes. And a mechanic can help you determine the knock sound when braking’s roots before recommending the best course of action.

Keep reading for more!

Knocking Sound When Braking Rear: What Are The Reasons?

Main Causes For Knocking While Braking

Why do you hear the clunking noise when braking slowly? 

There are 9 main causes for this issue: worn-out brake pads, control arms damage, bent rotors, faulty brake calipers, poor suspension components, loose bolts, ball joint failure, broken shims, and worn-out rotor disks.

Worn-out Brake Pads

Worn brake pads are one possible culprit of car knocking when braking. They are typically made from iron, graphite, and copper during manufacturing.

At one point, the brake pad wears down due to coming into contact with the rotors. A clunk sound when braking at a low speed will emerge, yet it is not usual.

In this case, change your brake pads whenever they show signs of wear. You may indefinitely harm or severely degrade other brake components if you don’t.

Ball Joint Failure

If your car shakes and clanks while you’re driving, a ball joint failure can be to blame. Your control arm may drop off if this is the case.

Operating at full speed can badly affect your vehicle once the fault is not fixed.

Loose Bolts

Loose bolts are the most likely culprits for the knocking sound. Brake pads may have dislodged, rattling the metal against the calipers or rotors.

Inspect the bolts immediately for apparent wear and change as needed. It’s an excellent idea to look for any signs of wear or looseness in all other braking system elements, such as pins and springs.

Suspension Control Arms Damage

Vehicles that are driven off-road frequently tend to have suspension control arms that are worn out. Wheels become out of whack, making a knocking noise when braking at high speeds.

Warped Rotors

In addition, bent rotors can trigger such a problem. The brakes overheat on long trips or when you brake aggressively, ending up with a clunking noise when braking lightly.

Track down and fix things whenever you spot anything wrong with warping signs. This way would halt more severe problems later on.

Poor Brake Caliper

A broken caliper could also be responsible for the knocking sound when applying brakes.

Once it is malfunctioning, the brake pads will rub against your rotor’s surface incorrectly, leaving a disgusting noise as the car slows down.

Should you doubt this is the case, inspect for warping or physical harm in all brake parts; replace them if needed.

Lousy Suspension Components

A dislodged suspension part, such as a ball joint, shock, or tie rod end, is a possible source of the knocking noise.

If these elements are worn or come loose, you may undergo unusual squeaking or a knock noise when braking.

Suspension parts could be at risk, so check them for signs of degradation or damage; if they do, get new ones at once.

Worn-out Rotor Disks

The titanium-based brake disk rotor (or any material) is a vital part of the braking system. Yet it may go wrong due to the worn or subpar brake pads.

Accordingly, the rotors’ surfaces won’t be as flat over time and get distorted during car washing with cold water while they’re still hot.

Uneven vibrations and a knocking sound when pressing brake pedal often result from the deflected brake pad’s surface.

Broken Shims

People often seal the tiny spaces between the pad and caliper to minimize brake noise with heavy metallic or rubberized glue.

When the shim is worn, it rubs against another metal surface, making a grinding sound.

Also, it’s common to hear a knocking noise when slowing to a stop. To this end, try to buy new brake pads as soon as possible.

How To Diagnose The Matter?

Ways To Forecast This Issue

You may face myriads of weird sounds from the car engines but do not know why.

For instance, you would fret if the car sounds like a lawnmower or like a helicopter when accelerating, besides the knocking sound when braking your rear.

No matter what type of noise, diagnosing steps is a must to pinpoint the roots.

If you discover a clunking sound once brakes are applied, clarify the problem’s source. Use these technical steps to spot the matter soon:

  • Check the shocks and struts.
  • Ensure the control rods up top are in good working order.
  • Check the tires for any damage or uneven wear.
  • Look for any leakage.
  • Verify the power steering rack.
  • Verify your lower ball joints.

How To Tackle This Issue?

Get The Appropriate Pads For The Car’s Brake

Check the brake pads and other systems to confirm your auto is safe to drive. A knocking noise may be produced by a non-original brake caliper or other elements of the car braking system.

It’s easy to accidentally purchase the bad parts since so many brake pads look the same. The usage of inadequate items can be risky.

This is because brake pads can be caught inside the caliper if forced to shift during hard braking.

Ratty brake pads can also trigger the pads to slant and lock in the caliper, which can bend the backing plates and strike the friction material, exacerbating the situation.

Change The Original Components Properly

Keep or obtain the original hardware when swapping out elements like brake pads. Also, check to determine whether the replacement parts are designed to work with the car’s braking system.

For instance, if a new set of pads doesn’t come with clamps, you can utilize the stainless steel silver clamps that came with your prior pads.

Some automakers use a black rubber shim in place of stainless steel components. Never use both shims to halt over-thickness, pad drag, and overheating. Just one shim set is needed for the brake pads.

Clean The Current Parts You Will Retain

If you keep using the old pieces, you should clean them to eliminate rust or grime.

Right and left brake pads typically have anti-rattle springs installed. Accordingly, if the original pad set contained such shims, they must be eliminated and cleaned before reusing.

Do Not Damage Replacement Parts

It’s also cautious not to break brand-new parts. You shouldn’t, for instance, warp the new components’ shims.

Remember in which direction you place them for the new setup before the replacement steps.

The caliper slides, where the end clamps or anti-rattle bands will fit, should be polished.

Clean The Parts From Rust Or Dirt

The shims won’t properly seat, resulting in the pads jamming in the caliper if the sliding ways are blocked up with rust or dirt.

It will make the brake disc overheat and cause a braking noise or a hitting sound. So clean off any rust and dirt.

Do Not Put On Much Of Lubrication

When working on brakes, you do not want a lot of grease in them because that could impair their functionality.

These pieces of hardware must enable pads to slide without touching.

Additionally, where the anti-rattle clips are positioned on the pad backing plate, you should apply a minimal amount of high-temperature oil.

By doing so, you speed up the movement of the pads. Apply lube sparingly and avoid getting it on the contact surface of your brake pads as a general rule of thumb.

Should I Get Fret With This Knocking Noise When Braking?

Is Knocking Noise When Braking Dangerous

No. When you press the brake pedal for the first time and hear a knocking sound, it’s probably nothing to worry about.

If you still believe the brakes are engaging and the vehicle is slowing down, it may be due to a minor annoyance that could be fixed by adjusting a setting.

The brake pads rattling inside the bracket is likely the source of the knocking sound, besides other roots stated above.

You can confirm a minor knock by applying the brakes while traveling on a rough road, but only if the knock is quick.

Until the sound has ceased, the pads likely operate again. If the noise persists, spot the triggers as soon as possible before it risks more significant issues.

To sum up, a knocking sound is something to be concerned about only if you notice that the brakes aren’t kicking and the car doesn’t slow down when you hit your brakes.

Final Words

Have you ever heard a knocking sound when braking rear? It’s a pretty ordinary matter in the car world. Understanding the causes is the backbone of the fixing schedule’s success.

Interestingly, this article has just left these concerns answered utterly. Just get inside the off-putting sound’s roots and head for the viable measures. 

On top of that, get your vehicle checked regularly by a qualified mechanic so you can catch any issues before they become serious problems.

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