Popping/crunching from rear

Ok… so I have a 1997 Taurus that I just put new tires on. Immediately after, I started noticing an occasional pop/crunch sound from the left rear. It may have been there before the tire change, but it may be new (the old tires were NOISY, but I’d be surprised if they could have covered up this noise).

I switched the rear tires to see if the noise would move, but I haven’t heard it since.

I also inspected the left rear brakes. Naturally with 12 year old drums, there was a fair amount of rust, but the brakes and all their components were there and in their proper place (new shoes and assorted hardware 2 years ago) with no visible signs of unusual wear. Brake dust galore, of course. The wheel bearing was nice and smooth and had absolutely no movement when I yanked on the tire.

The one thing I did notice with the brakes that may (or may not, I am not a professional) be an issue - when I applied the parking brake, a gap opened between the top of the shoe and the wheel cylinder. The cylinder slowly expanded to close this gap (took about 30 sec). I’m not sure if this is unusual or a sign of a problem with the cylinder.

Braking is good, and the car tracks nice and straight. No signs of loss of brake fluid anywhere, and no discoloration noticed. I have not tried bleeding from the left rear to check for any obstructions.

Any suggestions? Thoughts? Is there something I’m missing? Or is this most likely a bum tire (Yokohama Avid)? Thanks in advance!


I should add the sound is only noticeable at low speeds…


Sound returned, still from the left rear. It isn’t the tires. Still looking for advice…

Occurred intermittently this morning when accelerating out from a stop. Sounds a bit like a spring popping, but all springs seemed to be in excellent condition. I’m guessing the shoes aren’t retracting smoothly for some reason.

Barring other advice, I plan on replacing the drums (they are ancient anyway) and the wheel cylinder this weekend.

I thought you might have loose lugs nuts if you have a crunching noise. it would make noises at low speed and quiet down after you accelerate. You said you switched the rear wheels with each other and it went away. You probably tightened the lug nuts and cured the problem.

I would have hoped it was that simple - but the noise has been intermittent. It went away after switching the rear wheels but then reappeared later, still from the same wheel, despite all the lug nuts hand torqued to the proper level in the proper sequence.

I did see a nice video on how to inspect wheel cylinders. Based on that, I’m actually wagering that the problem doesn’t lie within the cylinder, but is more likely to be twisted/warped shoes and/or out of round/worn drums. Again, I’m just guessing, though. The drums are so ancient I really should replace them anyway, so I don’t feel bad spending that. And replacing shoes is really not that hard or expensive, so I’m leaning towards doing that at the same time, along with new springs just for the heck of it (those things are cheap). The cylinder does appear to move ok by hand or when stepping on the brake with the drum most of the way on (to keep the thing from popping itself apart).

So much guesswork, but I am fairly certain it is not tire/lugnut/bearing related as the noise hasn’t moved and isn’t there when moving the bearing with the drum off…

(appreciate the response, btw!)


The 12 year old drums could best be described as egg-shaped when measured (should have done that before)… The brake shoes were occasionally catching on the drum and the grooves worn into them… and then snapping back…

That explains why I had braking still (cylinders working just fine), but the noise was intermittent (just barely catching on certain parts of the drum at just the right speed and temperature)… and why there was a spring noise - as the shoes bounced back, the return spring made a nice noise.

Fixed easily enough for the cost of two nice new rust-free drums (only $38 each) and new shoes just for the heck of it.