What would cause the brakes to squeal?

myrns, Jan 15, 10:43am
I took off the brake calipers and pads are like new, I took out pads and gave then a scuff with 120 grit sand paper but still squealed after 10 minutes off driving, the car had been sitting for 6 months and just wondering ifthe old rust on discs may have something to do with it! TIA

richard198, Jan 15, 11:19am
Use Coppercote/High temp grease on the rear of pads.
The squeal is vibration between the piston and pad.

myrns, Jan 16, 4:00am
Thanks Iwill try that, I noticed the pads did not have the thin metal backing plate that would usually be there, could this also be the reason for the squeal!

tonyrockyhorror, Jan 16, 4:07am
Yes. Having the shims reduces vibration.

steve312, Jan 16, 4:12am
And could just be very poor quality pads.Many of the cheaper pads squeal regardless of what you do to them.Some brake places will be able to sell you self adhesive rubber anti squeal shims.They do work very well in a lot of cases (often better than the original shims).

kiwis0, Jan 16, 4:13am
There's Dust in them, wash them

myrns, Jan 16, 4:42am
Well as luck would have it I had a small tube of synthetic brake grease in my garage from yesteryear,smeared a bit on back of both pads and guess what.no more squealing!

richard198, Jan 16, 6:34am
De nada!

franko171, Jan 16, 6:36am
but do thy work!

frank1, Sep 25, 3:12am
The shims behind the pads are there for a reason--to stop brake squeal