"wheel of fortune" noise from rear when braking

[hirishdancer]

I have a Scion xA, 2006 with 230,000 miles on the car.
Last year I noticed a clunking noise coming from the rear of the car, I have had the breaks rebuilt, both front and back, it's not raised or lowered it's pretty basic, no cruise control but does have ABS. It was making this noise before I had the brakes redone.. and it still continues to make the knocking noise...

When I brake, I hear what I can only equate to is the noise from the wheel of fortune.. it's coming from the CENTER rear, and is fast when I start to break then as I slow, it gets more quiet, and the pattern slows.. ( like the wheel of fortune..)as I come to a complete stop. it does not make this noise any different to one side or the other when I turn, I am not feeling the knocks in the steering.. It does not pull to one side or brake oddly. it just.. knocks, It has been making this noise for over a year. several mechanics and even the dealer are stumped as to why it's making the noise. I have even driven the car with the mechanics in the car and get "..What IS that?!.. I have no idea.. we can't see anything wrong so it must be okay.." this is not a normal noise for anything to make.. does ANYONE know what the noise is!?

[Crvett69]

is it fwd or all wheel drive?

[hirishdancer]

like other economy cars, it's front wheel drive.....

it's a scion...

[DeltaP]

I've not done much work on Scions but I'd suggest getting it up in the air on an alignment lift. One where you drive it up on the ramps and then the chassis can be raised off the ramps after the car is up in the air. That way you can check all the suspension components and links etc for looseness with the chassis loaded and unloaded. Could just be a worn bushing or loose link, strut,etc. Congrats on the mileage.

[VAnoobie]

Are our rear brakes caliper like the front or housed drum brakes?

I had a similar clunking on my Honda with rear disc brakes. It was definitely in the rear. When I first heard it, I thought it was a truck beside me. It sounded a lot like the sound freight trucks make when they go "Tra-tra-tra-tra-tra-tra".

I could not find anything wrong or loose myself so I ordered new rotors and brake pads hoping that would fix it. While I had it taken apart, I checked my top and bottom caliper pins and the bottom one was a bit stiff. I took it out and regreased it, slid it in and out till it felt smoother and put everything back together with the new aftermarket pads and rotors. The sound has yet to come back. My guess was that the brake pad wasnt being applied evenly because of the stiff bottom pin resulting in slight movement of the pad make it thunk around. Whoever does your brakes should check the caliper pins and grease them if needed, but sadly some don't always do this.

If they are drum brakes, the drum housing may be slightly warped or have a small bit of play. Its weird that it would be from the rear CENTER only while braking. Have you checked your trunk for loose things? Check you spare tire for looseness? have you hit the rear hard over a bump?

[hirishdancer]

they are drum brakes... and EVERYTHING but the front calipers was replaced last year in the breaks.. but it was making that noise before I uave the breaks redone..

I have spent the two years I have had this car full time trying to.figure out what could be causing the noise. it's been in the air.. it's been driven.. It was rear ended while my ( now) ex husband was at a stop light and it was hit with the break depressed. woman behind him was doing 30 and plowed right into him. I do not think that the car was making that noise.when it left the body shop... ( there was a year long period that I did not see or have the car.. ) but in that year.. who knows what happened to it..

[VAnoobie]

Sometimes collisons do weird things. Could be something as random as the wheel bearings if hit hard enough. If you are as adamant about it being rear CENTER, As weird as it sounds, I would have somebody crawl into the back space with the rear seats folded down and things like spare tire, spare tire carpet/covers and easily removable panels taken out. Anything you can remove easily, take it out. Then have the person back there making close sure where the sound is coming from exactly. Sometimes something that sounds in center may actually be on the right and something in the left may even be right. It's a hassle but you never know what you might find.

[shorod]

Does your Scion have one brake shoe in the rear that is shorter than the other? This was common years ago but I'm not sure if the Scion is this way. You might pull both rear wheels and both drums then compare the length of friction material on all four shoes. See if two are longer than the other two. If so, make sure they are installed correctly. The rule of thumb was the shorter shoe should go to the front of the vehicle and the longer to the rear. If both shorts are on one side or the short is not in the correct location, the shoes might be grabby when applying the brakes can causing the noise. While the drums are off, inspect the shoes for any signs of contamination of the shoes, such as brake fluid from a leaking wheel cylinder.

Since you believe the noise is coming from the rear, find an isolated stretch of road and try applying only the rear brakes using the parking brake and see if the noise is present then. If so, you know the issue is related to the rear brakes. If not, then it's probably in the front and telescoping to sound like it's in the rear. Of course before trying this experiment you should confirm your parking brake works and releases fine. If the parking brake doesn't often get used it could stick when applied and you don't want to discover that when you are doing this experiment.

You might also check for a shop that has a ChassisEar. This is a system that have microphones in alligator clips that you can place in various locations on the car, then listen through headphones to each of the microphones, one at a time, and determine where the noise is loudest. Then it's a successive act of moving the other microphones closer to the loudest area until the noise is pinpointed.

-Rod