Brakes squealing badly with lots of dust on the REAR rims

[porter42]

New guy here. I searched the forums but I cant seem to find my specific problem and apologize if I'm reposting. I also apologize for the lengthy explanation. I'm no mechanic but I can explain the hell out of something.
I've got a 97 900 s 2.3 5 door. I replaced the front rotors early last summer and had my mechanic father-in-law inspect all the brakes while we had the time. I had purchased 4 rotors and all new brake pads but the old pads (oddly) had more meat on them than the aftermarket pads I had purchased. So, I brought everything but the front rotors back.
ANYWAY, there has been some serious squealing going on with the brakes and I can't tell if its coming from the front or rear. I suspect the rears because there is an ENORMOUS amount of dust collecting on the rears versus the front. The squealing starts when I put the brakes anywhere from just above zero to 1/3 braking force but stops if I push harder. It starts squealing again when the car is approaching a stop. When I release the pedal there is still a slight squeaking that sounds elliptical in nature. I was told by a non-Saab owner that its possibly the rear brakes grabbing and not letting go (hence all the dust). I cant see it being because of old pads because as I said, the pads had a lot of life left in them. Also, considering how much meat is on the pads, I'm pushing harder than I think is normal to slow down and there wasn't any improved braking after replacing the front rotors that were rotted and pitted. Do Saabs have soft pedals anyway? I really appreciate the help and this forum has already answered many questions I now don't need to ask.

[Demusku]

Im not an expert on brakes but id say make sure the calipers are working and not stuck and check the pads didnt slip out of place. On my Mark VIII i had both my rear calipers freeze made all kinds of noise and had alot of dust for being ceramic pads and on my taurus i had a pad slip out of place that made alot of noise. Generally when i have brake noises i check that the pads arent cracked or anything then i check the calipers.

[BobSaabit]

Squealing is usually caused by either worn out pads (metal on metal or the pad's wear indicators hitting the rotor) or by vibration. Vibration in used but not worn out pads is sometimes caused by dirt or a lack of grease on the contact points (where the pad meets the caliper). Pads do need to move minuscule amounts and if they have friction it can lead to harmonics developing. Pads can also get glazed, leading to noise, but a few high speed stops in a row will usually remove that.

If it were me, I would pull both sets of calipers and check the pads. If they are worn unevenly, replace. If the rotors are not smooth, either turn (unusual these days) or replace. Regardless of what you replace, clean the calipers and use some high temp molly grease on the points where there's metal to metal contact. Make sure there's no rust/corrosion at those points.

[win_k]

Originally Posted by BobSaabit

If it were me, I would pull both sets of calipers and check the pads. If they are worn unevenly, replace. If the rotors are not smooth, either turn (unusual these days) or replace. Regardless of what you replace, clean the calipers and use some high temp molly grease on the points where there's metal to metal contact. Make sure there's no rust/corrosion at those points.

I'll second that, with the possibility of using sand paper to de-glaze the used pads rather than replace the pads.

Just a touch of "disk brake quiet" (very high temp grease) between the caliper and backs of the pads can make an astounding reduction in noise.

[porter42]

Thank you, gentlemen. Looks like this un-mechanically inclined dude has some work to do.