[Shop-talk] Squeaky brakes

[Larry Spector]

It could also be the pad compound itself. Some of the more aggressive pads
tend to make lots of noise. Check out rockauto and see what the options are
for your Mercedes. IIRC, the newer ceramic compounds tend to be quieter
than the older semi-metallic compounds.

On May 16, 2017 8:55 PM, "Richard Beels" <rbeels at yahoo.com> wrote:


Don't know your specific car, so general advice...

how's the surface of the rotor?  old crappy rotor and new pads are a recipe
for crappy braking.  if they're both new, have they been bedded in?
6 quick decel runs of 60-10 should get the brakes up to temp and get a good
transfer layer on the rotor.  if they smell after 2-3 stops, keep going,
that's just the initial burn off of remaining volatiles.  make the stop
aggressive but don't get on the ABS.  Don't stop during the runs and do
them right after each other.because we want the brakes to heat up.  They
might fade too, so beware - safety and all that.  Then coast to a stop (use
e brake if it's internal to rear rotor) and do a _quick_ check of each
rotor to make sure they're all hot and stinky.  Then go for a 5-10 minute
drive to cool the brakes down.

Anti-seize on where the pad slides is wrong. brakes are too hot and it
turns to glue.  I use either syl-glide or the permatex purple ceramic
lube.  there should be thin metal (Stainless!) clips that go over the
caliper (bracket) that the pads actually ride on.  and the pads should move
in and out easily by hand.  but not so loose that they can wiggle
clockwise/counterclockwise when looking at the back of the pad (if that
makes sense).

something i see occasionally is too much lube in the guide pin, which can
cause "hydraulic push" and the pin doesn't fully retract at rest.

if the pads have a shim clip, it needs a dab of purple goo in between the
shim and the back of the pad.  I also rub a little purple goo on the piston
edge that touches the back of the pad, around the whole lip/edge.
eliminating non-lubed metal to metal contact is the goal here.



At 05/16/2017 at 14:28, Shakespearean monkeys danced on eric at megageek.com's
keyboard and said:

> OK, I'm at my wits end (it's true that was my STARTING point, but still)
>
> I bought a new (to me) 2007 Mercedes GL450.  It's in great shape, garage
> kept and clean.
>
> After a week or so, the brakes make the typical squeal when applied
> lightly after a longer trip.
> So I checked all the pads. They were almost brand new.  So I blew them out
> with air (note, I didn't disassemble them at this time.)
> Another week so goes, squeal get worst.  Drives my crazy.
>
> Last night, I pulled apart each wheel, cleaned everything.  I added CRC
> Anti-noise goo to the back of the pads, cleaned the caliper pins and
> applied permatex caliper pin lube to them.  Finally, I placed a bit of
> never-seize silver goo to the matting points of the pads and calipers
> (After wire brushing the surfaces to clean them.)
>
> Blew everything clean and reassembled.  This morning, I got a little
> squeal after my 50 min commute to work.
>
> WHAT CAN I DO NEXT?  I hate brake squeal, and it kills me when I do so
> much work and don't get any real results.  What am I missing?
>
> Should I try to 'rough up' the pad surface? And if so, what is the best
> method to do this?
>


Cheers!

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