A noise has developed rather quickly in the rear area of the 1997 Legacy L AWD sedan with auto (157,000 miles). The noise is generated by hitting sharp bumps (pothole type), comes from the rear end area and sounds just like a loose toolbox in the trunk, a sharp clunk/thump/rattle. At first I thought it was the muffler hitting the heat shield (I was able to move the exhaust enough to do that), so I replaced all of the rubber mounts on the muffler. It tightened it up so it wouldn’t contact the heat shield but had no effect on the noise. Now here is another interesting characteristic, the noise will not occur if the brakes are applied. If the service brake is applied the noise will not occur and if using the parking brake, it diminishes but does not disappear. Couple of other inputs, on Monday I had the car on a lift for an inspection then the same day it was in for a rotate and balance. With that, the noise didn’t develop until Thursday and it was instantaneous.

 

Any comments/suggestions would be welcome.

Sounds like maybe a strut mount. Otherwise check for loose components and give the rear suspension a good shake down, no broken springs, etc

Sounds like maybe a strut mount. Otherwise check for loose components and give the rear suspension a good shake down, no broken springs, etc

Roger that. I did have it up on ramps and went around with a rubber mallet to see if I could find anything loose, then jacked it up, pulled the rear wheels and repeated the "whacking" process. Couldn't find anything obvious but will pull the wheels and recheck the struts.

This is the piece where the strut mounts with the studs to the body. Sometimes they rust out and rattle around. Could be other suspension issues too.

As embarrassed as I am to say this, the problem, which was diagnosed by the mechanic at the stealership (I gave up) was the lower bolt holding the right rear caliper had fallen out allowing the caliper to pivot upward (after hitting a sharp bump) and strike the inside of the rim. This would explain why the noise wouldn’t occur with the brakes applied as well as why the noise starting immediately with no ramp up.

 

Thought this would be an interesting situation to put away “just in case”.

MAN! how cool would that have been had you whacked the rear caliper with that mallet! that would have been awesome..oh well, there's my problem!

caliper bolts falling out is a very, very strange thing. i would imagine that at some point along the line that rear caliper bolt was removed for some reason and was either stripped (very unlikely) or not torqued tight enough. aren't too many bolts i've heard of coming out...and calipers bolts are not one of them.

ahhhh ok I guess that would cause that problem! I had wondered what would happen if one of those bolts came out, now I guess I know! Does anyone drill those and safety wire them?

OK, here's what happened, the dang bolt just backed out, didn't shear, didn't break, just came loose and dropped out, so the threads were fine. The last time the rear brakes were worked on I did pads and rotors about 18 months ago. Now I am very specific about using factory torque specs on everything I touch, so I am puzzled why this happened. I checked the other three wheels and every upper and lower bolt were to spec. According to the two mechanics I spoke with, they had never seen it happen. Great, I get to be the #1. Anyhow, when I would hit a sharp bump, it would kick the caliper up, hitting the inside of the rim. Now this amount of travel didn't move the caliper off the rotor, so the pads weren't in danger of dislodging or dropping out (a good thing), but when it hit the rim, it did make one heck of a noise.