Heat temper brake pads

[Mark R]

Mike,

I have a wholesale account with a big east coast tool distributor.  The
problem is that whenever I place an order, I end up spending WAY too much
money on personal tools... so I feel your pain!  $4.00 book with some good
tips... sounds like a "score" to me!

The goal is to maximize braking efficiency and torque.  After all, pads and
rotors will work (in a diminished capacity) without any "break-in"
procedures.

Baking pads would work to burn off organics (greases, oils) and you'd want
to be near the top of a toaster oven's range (375-400 degrees F, give or
take) for 20-30 min.  Of course, this may or may not leave toxic residue in
your toaster oven.   =)
Oh, and backing plate paint would probably start to burn off, especially on
a street pad.

OK, so this might be a good way to "break-in" a set of pads.... but the
racers and technical folks among us call the necessary process something
else.  "Bedding in the pads."

A critical part of the bedding in process is to heat up the pads enough to
burn off things (organics, binding compounds, etc.), but that's only 1/2 of
what's going on at the pad.  On a more minute level, I'm told the friction
material is softer during this process which allows for two things:
1.  Directional alignment on a molecular level (which may or may be bogus...
I've never seen electron microscope scans to prove this out).
2.  Increased pad wear to match the pads to the rotors (high spots are
quickly worn away so that there is even braking force between the pads and
rotor as wall as maximizing the available surface area).

I do know that some pad manufacturers have had verbiage about only putting
pads back onto their first installed position (no flipping in/out, axles, or
left/right).  I have no idea if this is due to even wear with the rotor
(likely), or the possibility there is in fact some form of molecular
alignment increasing the bonding of the friction material.

The other critical side of the equation is what's going on at the rotor.  At
the rotor, some material is embedded into the face of the rotor and
increases the coefficient of friction.  This is "bedding in" as pad material
is evenly deposited to the rotor face.  Baking the pads before hand might
preclude this process from occurring.  I see faint pad outlines on rotor
faces frequently.  Localized transfer has occurred, causing a hard, high
spot.  With sensitive brake systems, you can actually feel it in the pedal
as a pulsation.  The pad face temperatures when bedding in (even for a
street pad) would exceed a household oven's temperature.  My track pads
aren't supposed to lose their friction until 1250 degrees F (that's face
temp, not backing plate or caliper temps).

I can see a few situations for baking a pad in an oven.
1.  Where bedding in is impractical or dangerous (like on an airplane where
there's not enough runway to safely heat up the brakes).
2.  Where rotors preclude normal bedding in processes due to their
coatings.  ATE slotted rotors come to mind since I've installed a bunch of
those, including on my Escalade EXT and my mother's BMW 330ix.
3.  Decontamination.

Make sense?  Anyone else has thoughts or experience on the subject?

Mark Rosenkrantz
PA-28R-200 based at CZG, Endicott, NY (so I've not purchased Mike's book on
C-150s, yet).
A few Audis. a trailer, and a few American vehicles.




On Fri, Nov 14, 2008 at 4:17 PM, Mike Arman <Armanmik at earthlink.net> wrote:

>
> Two places I should never go when I have cash in my pocket - tool stores
> and used book stores.
>
> Anyway, bought a copy of a hot-rodding book by a guy named Wayne Scraba,
> bunch of tips and tricks
> for the go-fast crowd, best $4.00 I've spent in a LONG time.
>
> He talks about putting new brake pads in a toaster oven (not one that you
> ever plan to cook food in
> again!) and heating them for 30 minutes to temper them - drives off the
> VOC's, sets the adhesives, etc.
>
> He omits to mention how hot.
>
> I've been all over the internet looking for this one last (vital) tidbit,
> and can't find it OR him -
> I did find an e-mail for him but it bounced back as unknown.
>
>
> Anybody know anything about this? How hot should I be baking new brake
> pads? Or is this "old-tech"
> and we don't need to do it any more?
>
> (And I think this might also be applicable for bonded shoes on drum brakes,
> too.)
>
>
> Best Regards,
>
> Mike Arman
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