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Refacing front brake pads
For a reason I cannot establish yet, the front brakes suffer bad squeal.
After fitting  new pads they are fine, but typically after a track day they 
will begin to squeal. A light tap on the brake pedal will stop the squealing, 
but this only stops for a few seconds. They seem to worst driving in a straight 
line, turning the wheel even very slightly will reduce the squeal.
Perhaps some glazing is the cause.......old pads:-
 
The pads wear more at the top of the pad compared to the bottom, perhaps
 2-3mm in some cases.
I would suspect wheel bearings, but these were renewed only a few thousand miles 
ago.
I wanted to look at a way of re-surfacing the old pads because there is still plenty of 
material left on them, just that the wear is not exactly even from top to bottom.
I wonder if the pressure from the springs behind the caliper pistons is overcoming the 
friction of the seals against the piston circumference and is actually driving the pistons 
out on their own. I could pull the pistons out and clip a spiral or two from the springs, but 
first I will try skimming some old pads to accelerate the wear by a mm or 2 each time 
the squeal re-appears. I should end up with nearly worn out pads if the squealing continues 
to the point where the pistons springs won't be having the same affect as is the pistons 
were fully pushed into the calipers.

I have no clue if the following is an acceptable practice........but I like to try stuff out.........

I could really do with a small milling machine (cheers MR for that thought !!), but I have a drill press,
so would make use of that. The pad material is actually quite crumbly. Ever taken the edges off 
with a file ?, material comes off really easy.
 
Grind the point flat on the largest drill that will fit in the chuck.
 
 
 
 
 
The pad material is soft enough to be able to remove ~1mm of material at a time 
and slide the pad by hand !

Youtube video here.

Light dusting with a flat file.........
 
Re-surfaced pad on left, new pad on right. Apart from slight colour difference (old pads 
were ex trackday, so have had quite a bit of heat though them, surface texture was the 
same. 
 
The back of the pads have a sticky pad which stick to the pistons and presumably 
help prevent squeal (yeah...right). Because these are old pads going back in, the 
"sticky" bit, is not sticky anymore, so......
Wurth anti-squeal spray, good stuff which I used to cure squeal from the rear brakes ....
........which was'nt actually coming from the rear brakes at all :-)
Still "worth" a try on the fronts.
Brake bleeding.
I bled the brakes before the trackday, and again before I re-fitted the re-surfaced pads, 
air bubbles came out on both occasions !.
 
Been out for a drive, only a few miles, problem is that I don't expect the squeal to re-appear 
unless I drive at least 20-30 miles.
 
 
 
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