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Knocking Noise


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#1 edwintokar

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Posted 11 November 2010 - 12:29 AM

I have a 2001 Toyota Corolla with over 200,000 miles ( 80% highway, I commute 350 miles a week). It recently developed a loud knocking noise whenever I apply the brakes. The harder I brake, the louder the noise.
A Google search led me to believe it was the CV joints; however, I have inspected the CV joint boots, and they seem to be in perfect condition...no rips or tears, and no oil or grease seems to be leaking out.
This knocking noise only happens when I apply the brakes, not when I am turning a corner. Also the sound seems to be coming from the rear, particularly the left rear tire.
I recently replaced the rear break drums ( I didn't touch any of the other brake mechanisms), but my wife says this knocking noise started before I did this.

Any thoughts?

Thanks

Edited by edwintokar, 11 November 2010 - 12:31 AM.

#2 fishexpo101

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Posted 11 November 2010 - 09:24 AM

Could be a number of things. Loose suspension (strut, spring, upper strut mount), loose nuts/bolts (axle carrier bolts), damaged suspension bushings, loose sway bar, damaged end links, excessive slop in the rear drums, something shifting inside the car, etc.

Could try jacking the rear of the car in the air, spin the rear tires by hand and hit the brakes. See if you can duplicate the noise in the air. Since it is knocking this much, loose suspension piece should be pretty obvious. May need to through a floor jack under the rear axle carrier in each corner to compress that corner (load the suspension) and see if anything looks damaged.

Could be something completely unrelated to the brake/suspension. A loose muffler, exhaust leak (exhaust donuts are known to blow out easily in this generation), bracket any any of the EVAP lines that came loose, even a loose gas tank strap.

On my 2002 Corolla, I had a weird thumping noise on deceleration and braking. Couldn't figure it out until the wife took it to the car to shop. She ended up hitting a speedbump at a good clip, which ended up loosening further, the culprit of the thumping noise. Turned out, it was the axle carrier bolts, the big ones that hold the bottom of the axle carrier to the strut assembly. Those were completely missing, caused the whole strut to be separated from the rear attachment point.

#3 cesar

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Posted 11 November 2010 - 09:38 AM

Are u sure the noise is comming from the rear?  If u arnt 100% sure i would highly recommend u get the front disks resurfaced. They will only charge u bout ten bucks per disk. Unless ur mechanic says u need new disks. Wich cant be around 25 bucks each.

#4 edwintokar

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Posted 12 November 2010 - 11:40 PM

Thanks for the answers...
The noise is too regular to be something loose or bouncing around. It's one 'knock' per tire revolution. When I break hard, I can actually feel each knock through the brake pedal, but not in the steering wheel, which makes me more sure that it's from the rear.
I have jacked up the back end of the car and pushed and pulled on everything that looks like suspension, but nothing is loose. Same for the front end. I tried spinning the tires by hand, but could not get them going fast enough. The lightest touch of the brakes stopped them instantly.
I replaced the front rotors just a few months ago, so I doubt they need resurfacing, but I'll look at them again.
I will pull off all the tires this weekend and check that everything is seated properly. Anything else I should look for that could cause this sound?

#5 cesar

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Posted 12 November 2010 - 11:51 PM

What about the wheel bearings?
I had a similar issue but in the front wheels.
It started as a low thumping noise then it gradually became
More noticeable. In my case i had to replace a bad wheel bearing.
It was making a sound just like u mentioned..
Just one thump per tire rev.