2014 Mazda CX9 ebrake squeal - why can't I fix this problem?

For the past year+ SWMBO's 2014 CX-9 (with 80k miles and otherwise in great shape) has had a terrible squeal from the driver's size rear ebrake. I've taken it apart multiple times, new rotors, new pads, new shoes, and it keeps coming back soon after I reassemble - and seems to get worse when the brakes are warm, as it squeals more after extended driving, even when ebrake is off and regular brakes are not applied.

- rotors and pads are pretty new and rotors look perfect. These have the single-piece drum-style ebrake shoes (never seen that on other cars before), and I've replaced them once already, at this point I'm just wondering if there's something dumb I'm overlooking. The return springs on the shoes seem to be fine, as well. Cable adjusted to the requisite number of "clicks" to hold, etc. I've done plenty of drum-style ebrakes (and main brakes) and never had any problem like this - but none of them use this style of shoe.

SWMBO is driving me crazy with this and I'm too cheap to tell her "just take it to the damn dealer" (though I'm almost at that point....). Now it's the middle of winter and it's cold in my driveway and if I have to take it all apart again I want to have some idea of what I can do differently this time to make it work.

So, anyone have any ideas?

not knowing a dang thing about those specific brakes I'll give you some generic squealing advice that worked for me and the brakes on the wifes forester. when you disassemble it this time use break cleaner on the slide bolts (or whatever your truck uses to slide the caliper) spray it in the holes the slides go into and clean the slide pins thoroughly, try to remove all the old lube. Now use whatever lube you use for your brakes and generously lube the ever loving hell out of the slide pins, the back of the pads, wherever the pads slide in, but not so much on the pads area that it can get on the pads. Funnily enough, until I did this the brakes were quiet when the system was cold so I gave it no thought when testing it. Only after  my wife started driving it and it warmed up did it squeal. Its a good place to start.

So the ebrake squeals while the car is in motion, even when it's not applied?

How did you come to this conclusion, jack up the car and spin that wheel with the caliper off? I'd be tempted to confirm by removing the ebrake shoes completely. If it's really from the ebrake shoes, then maybe the backing plate is bent, not allowing them to sit correctly?

Does it squeal more going around corners than in a straight line? Is it a high-pitched squeal, or a lower-pitched rubbing/grinding squeal?

I've had a few rounds with these brakes. We had the opposite problem where they just wouldn't hold on any slope. Did you try turning the adjusters inside the rotor hat?  It sounds like they are set too tight and won't let the shoe pull away from the rotor hat.  There's a rubber plug you can pull to access the adjuster to avoid removing the rotor.

yes, adjusted them many times, from the adjuster and from the cable. And they've NEVER held well on a hill since we got the car, frankly. 

obsolete said:

Does it squeal more going around corners than in a straight line? Is it a high-pitched squeal, or a lower-pitched rubbing/grinding squeal?

you're leaning toward a dust shield grinding, but I know that sound well (and to check them) as a long-time rally guy lol. Dust shields are fine, nowhere close to anything (I've even bent them back further). I initially thought that would be the issue, but no dice...

In reply to irish44j (Forum Supporter) :

Yep :) On Subarus the backing plates would rust and bulge into the back side of the rotor, causing the noise. I figured Mazdas might have the same issue...it was worth a shot. Good luck!

Are the shoes too thick? Like their width maybe rubbing the rotor?

bobzilla said:

Are the shoes too thick? Like their width maybe rubbing the rotor?

Yeah my next move is too buy a different set of shoes and see if they work.... They don't seem too thick as the rotor goes on fine without hitting them. But who knows

The first gen forte had this style ebrake and never had a problem. 

One thing I found I was doing wrong, or not doing, was putting slack in the cable after installing the new shoes.  Years of tightening the cable had moved the adjustment point up, so I began again by cranking the cable way loose and focusing on getting the adjuster at the shoes set right, then the cable was tightened.  The shoe adjustment took several iterations of too tight/too loose, but eventually it would hold (mostly) on a hill without dragging.  These are the shoes that I bought from Tire Rack that eventually worked.