I can hear a knocking sound coming from my front left wheel when brakeing at above 40 mph.

It started after I took a road trip to Indianapolis (only 60 miles away). But it has progressively gotten worse to the point that when I brake at high speeds it makes a very loud knocking sound. I also notice that once I have almost come to a stop and i am barely applying the break it feels like the brake is applying then slipping over and over.

My car has 156000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
In may cases the knocking sound coming from the wheel area is caused by one of two issues; a warped brake rotor or the wheel bearings that are beginning to wear out. Vehicles made after the late 1990’s (like your Malibu) have a single wheel bearing that was designed to last quite some time. However, if they’ve never been inspected or replaced, that could be the source of your noise. However, the fact that you’re having braking issues could indicate a different issue. The best bet is to contact one of our local mechanics to diagnose the knocking noise firsthand and repair this issue for you.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

If you hear a clunking, or knocking sound, there`s a good to fair chance that it`s loose bolts. Check to see if your bolts are tightened. If the problem persists, there are a variety of different components that could be the cause of the clunking sounds. It could be loose calipers that would need to be tightened.
Bad Tires/Bad Left Tire – A knocking sound may be heard when tires go bad, if they are unbalanced or misaligned, or if there is a broken belt in one of the tires. Wheel Bearings – If a wheel bearing is severely worn out the wheel will not be able to spin freely. This may cause a knocking sound to be heard.
The clunking noise while braking could also be because of a damaged brake pad. Consequently, it can result in brake failure. In other words, if the brake pads are misaligned, they can easily hit the nearby parts and make noise.
Knocking Noise when Accelerating

If your car makes a rattling noise when accelerating, it could be your engine is worn out with low oil pressure or piston slap. If your car makes a humming noise when accelerating, it could be an issue with a failing wheel hub or a drivetrain concern.

If you just had your brake rotors cut or machined and installed them with new pads but you hear a rhythmic thumping sound, it`s likely a rough finish on the rotor. The rough finish on the rotor acts like a screw to draw up the pads. The thump comes when the pads snap back to their original position.
In most cases, when you have a problem like this, it`s caused by a loose or damaged strut, strut mount, stabilizer bar bushings or CV joints being worn out. The stabilizer bar bushing specifically is usually the part that would cause the `clunk` sound when hitting a bump.
Rattling noises that appear when you`re driving over bumps, or on uneven surfaces, are often down to the suspension. These rattles can disappear once you speed up a bit or when the going gets smoother. The culprits may be the drop links (e.g. if they`ve snapped), worn bushes or corroded shock absorbers.
A clunking noise when braking at low speed usually indicates worn out or damaged disks, rotors, calipers, or backing plates. It`s also important to check the suspension system, especially the bushings. Any issues with the suspension system will create loose movement when you brake, which will cause clunking.
FAULTY KNOCK SENSOR: SYMPTOMS

Engine warning light comes on. Error code is stored. Reduced engine power. Increased fuel consumption.

A knocking sound is usually due to a problem with the internal components of an engine. Driving while you hear a knocking noise is not recommended. The more engine damage you cause to these internal components, the more difficult and expensive the repair job will be.
It`s easy to misdiagnose the cause of engine knock, so you might have to pay a visit to your mechanic. Each of the engine knock causes on the previous page has a specific cure, and most of these fixes are simple. However, it doesn`t guarantee the knock will go away.
Knocking can damage the surface of the piston, the cylinder walls or the crankshaft bearings, all of which are expensive to repair. Modern computer-controlled injection systems can correct your fuel mixture to prevent knocking, but at the cost of engine performance.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

I can hear a knocking sound coming from my front left wheel when brakeing at above 40 mph.
ANSWER : In may cases the knocking sound coming from the wheel area is caused by one of two issues; a warped brake rotor or the wheel bearings that are beginning to wear out. Vehicles made after the late 1990’s (like your Malibu) have a single wheel bearing that was designed to last quite some time. However, if they’ve never been inspected or replaced, that could be the source of your noise. However, the fact that you’re having braking issues could indicate a different issue. The best bet is to contact one of our local mechanics to diagnose the knocking noise firsthand and repair this issue for you.

I hear a whooshing sound when I turn the steering wheel. If I make a sharp turn, I hear a grinding sound coming from the back. ???
ANSWER : Hi there. In most cases, the rear knocking sound is caused by the driveshaft, drive axles, differential gears, transmission mount, or the rear struts. The sound you’re experiencing is very difficult to diagnose, but could be caused by the power steering shaft, or you power steering system being low on fluid. It might be a good idea to have a professional mechanic complete a car is making a noise inspection.

Sudden play & random tugging in steering wheel. Hear clicking from steering wheel & front left tire both while driving straight.
ANSWER : Hello, thank you for writing in. Checking the brakes was a great place to start. At this point the first thing we need to find out is if symptoms happen always, or only when driving over bumpy roads. If you feel it only when going over bumps, you want to check the suspension. If the suspension is not up to par on the vehicle, you will feel and fight those forces in the steering wheel. You can perform a bounce test, and do a visual inspection to see if the suspension shows any signs of leakage or damage. This would include the ball joints. If the suspension seems to be okay, you want to turn your attention to the rack and pinion. For more help with diagnostics and resolving the issue, contact our service department.

When I put my foot on the brake my back left brake light goes off, when I take it off the brake the brake light comes on
ANSWER : I would suggest trying to disconnect and reconnect the wiring to the rear lights. I have seen these older Toyota vehicles rear lighting short out on the lights themselves due to the way the light circuit was made on the lamp housing. Look at the housing circuit on the light to see if one is touching another, and that could tell you why it is malfunctioning. There could also be a problem with the brake light switch. If you are not comfortable dealing with wires, I recommend getting in touch with a certified mechanic who can look at your brake light issue for you to see what’s going on.

my car is making a knocking sound on the left front wheel when driving on bumpy road. I changed wheel bearing and my mechanic cant
ANSWER : A banging or rattling over bumps can be caused by several different suspension components. A worn strut can make noises as can the upper strut mount. The strut mount allows the strut assembly to turn and move up and down. If the strut mount is worn, it can allow the strut assembly to rattle or bang over bumps. Stabilizer bar end links or bushings can also contribute to a banging noise. Worn end links can allow movement in the bar, and the bushings where the bar connects to the chassis can wear away and allow the bar to contact the chassis. Even a worn tie rod or ball joint can cause noises over bumps.

Since so many components can be causing a noise over bumps, have a certified technician inspect the suspension to isolate the exact cause.

Very Loud Knocking noise from left rear wheel when turning left and braking
ANSWER : The problem could be in the transfer case unit, but the device is mounted closer to the driver than the rear wheel so the noises or vibrations are generally a little more obvious. Especially during sharp turns the transfer case and rear end assemblies are working pretty hard with the wheels turning at different rates. I suggest hiring one of our mobile experts to diagnose the noise you’re hearing. Wheel bearings and worn out suspension components like sway bar links cause similar noises.

Can front wheel drive car engine power rear wheel drive
ANSWER : Anything is possible with enough engineering. The changes you are looking at would take major structural changes and would definitely not be an easy job. You could possibly consult a manufacturing engineer to get more details on how this could actually be carried out and whether it would be feasible.

over the last 2 months I started hearing this knocking noise that has gotten louder and my steering wheel kinda shakes.
ANSWER : A real shop would perform a 75 point inspection while the car is in their care. If they see that you need tires and struts on the second approach, then they are not a real shop. The noise that you are hearing is not the CV Shaft but rather the wheel bearings or a loose suspension part. A continuous knocking noise that is heard and gets faster as you drive would be a wheel bearing with a flat spot. If the noise just gets louder and not faster would be a non rotating item that could be loose on your suspension or steering. The shaking of the steering wheel could be caused by the tires if they are cupped. If the tire tread is cupped, then the shock absorbers are not working. Then the shocks and tires need replaced.

I recommend seeking out a professional, such as one from Your Mechanic, to help you diagnose your vehicle shaking issue if you cannot find the source.