Different pad compounds do different things...consider now that asbestos pads are history (healthwise), most pads are metallic or some form of semi-metallic material. So there are more complaints about brake squeal nowadays than ever before!
And why not? Hot metal against really hot metal!
Fortunately there is a cure. For our cars, two things are the culprit...slight pad movement against the disc and/or calipers, and warped rotors.
The first symptom is easiest to fix. Get some brake paste (or brake grease, or brake spray) at the local auto parts store...different names for products that do the same thing.
Remove the pads and apply the product on the brake pad backsides (the side that contacts the calipers, not the disc). Reinstall the pads.
I've used paste before with good results, but this time I tried the spray as an experiment since I did my W124 front pads this weekend...so far no squeal!
If your rotors are warped, it may contribute to the noise...and btw, there isn't much factory tolerance for turning rotors, so replacement is the norm...fortunately, they are fairly inexpensive.
The rule of thumb here is to replace rotors once for every two to three brake pad jobs you do.
Now I hafta do the ML pads this weekend...
