In an effort to educate our customers (current and prospective) we want to address a few braking specifics when it comes to installing, bedding-in and running/racing a big brake kit.
The Main objective in bedding-in the brakes is to get the pad material
to transfer onto the rotor surface evenly. Several things will disturb
this process, I will try to cover all of them. Driving this kit like a
grandma, (the way you drive when you are trying not to spill your
coffee) will NOT help you or your brakes. Honestly it is possibly the
worst thing you can do if you did it for the first month or so, of
occasional driving. The pad material will
only transfer evenly if the rotor is at the proper,
consistent, uniform temperature and the rotor "is true". The trueness
your rotors is integral to uniform pad material deposition (on to the
rotor surface). First we will cover rotor trueness, because there are
many things that can cause your rotor to run true/un-true. What many
don’t consider is that a .001 chunk of dirt or debris on the hub
mounting surface can cause more than twice, sometimes 3 times that
deviation at the rotor braking surface. Next I will cover the
bedding-in process, as this is not a stock set of brakes and these
require quite a bit more heat than a street set of pads. When this
procedure is followed you will be rewarded with long consistent pad and
Several things will determine the trueness of your rotors.
1. The original rotor mounting surface (the hub face) has to be true. We have had more than one customer that had a bent hub and in one case we
sent out a new set of rotor hats just because they were so angry and
insisted the fault was with our kit. This obviously did not solve their
problems, and it cost both of us plenty of time and money. We still have
yet to receive the undamaged rotor hats in return, even after this
customer found and admitted that their hub was bent.
2. The hub face has to be clean. We recommend a
wire brush or a Scotch-loc (on a die grinder, as shown in the instructions) and in many
cases a small file to knock down any burrs or dings in the steel
surface of the hub face will be required. Pay close attention to that face, and how
clean and blemish free it is. I have seen several hubs that had a small
piece of rust, dirt, even a crescent piece of aluminum or steel. Sometimes this
turned out to be from removing an aluminum wheel or old rotor hat "not
carefully". Also from installing the AZP rotor assembly "not
carefully". This crescent was stuck in the threads and when the rotor
hat assembly was installed it was pinched between the rotor hat and the
hub face. It left a depression in both the rotor hat and the hub face
that had to be filed out using a small machinist file. If the rotor hat
assembly goes on not true, do not force it, remove it and try again
slowly, until it slides all the way on to the hub centric center
diameter of the rotor hat, making sure both surfaces are clean and rust free. Also I
have seen where someone removed the old cast iron stock rotor, using a
hammer on the inside rotor surface. While entertaining and thoroughly
satisfying as a removal method of your old failing brakes, they failed
to notice that the rotor or the hammer left an upset edge on the hub
that no matter how tight you made the lugnuts this still left the rotor
assembly untrue. Only solution was, to use a file to make sure we
removed this deformation completely.
3. The interface between the rotor hat and the rotor has to be clean and true.
Since this is a two piece rotor, this interface introduces another
possible place for error. During my assembly procedure I clean and
inspect both surfaces thoroughly. I have had to remove casting burrs or
small dings with a light filing. I am very careful not to disturb this
interface while torquing the fasteners. There have been cases where I
missed a piece of debris and of a small (very small) piece of paper
towel being left in between these faces. I try to take as much care
during assembly as possible, but it HAS happened. If you need to remove
the rotor from the rotor hat. The 13.06" and 12.19" rotor torque spec
is 24-27 ft/lbs on the 5/16-18 socket head cap screw with a 1/4 inch
Allen Head Socket. The front 14.25" and rear 12.9" use 1/4-20 threads
with a 3/16 inch socket head cap screw, and only require 15-18 ft/lbs.
During re-installation install all fasteners all the way down to the
locking washer, leaving them just loose enough to feel slight movement
between the tolerances of the fasteners and the holes in the rotor.
This might take 3 hands but its worth the hassle, place a paper towel on
the work bench (so as not to scratch the shiny rotor hat face) hold the
rotor hat down or fasten it to the bench if you can, and apply a
rotation opposite the arrow to load and help center the rotor hat on the
pattern of fasteners, torque two opposing fasteners and continue to
tighten the rest in a star pattern as you would lug nuts, again torque
to 24-27 ft/lbs (for 5/16-18) or 15-18 ft/lbs (for 1/4-20) depending on
your fastener size.
Almost all the cases where customers experience an issue. One of the 3
items above solved all of their problems. By removing the rotor hat
assembly and paying close attention to detail when performing these
steps you will guarantee that you will not have a problem with trueness.
After confirming there are no issues with the items above, this next
very important, because you "can" cause irreversible damage to the rotor
(this might only solved by aggressive turning of the rotors on a brake
lathe, or possibly blanchard grinding, performed at a quality clutch
re-builder or machine shop).
Fortunately 99% of the time going back thru steps 1-3 has solved the
Another factor in rotor trueness, is initially (the first time) raising
the temperature to its
maximum uniformly and slowly. Very much like a fresh motor you do not
want to fire up a
stone cold brand new motor and do some wide open throttle drag passes to
max boost and speed, this will most surely result in permanent damage
time. Likewise you do not want to hammer the brake pedal on stone cold
performing the bedding process. The objective is to raise the
temperature slowly and uniformly. There are a few differences (with
respect to heat
cycling) between your new rotors and a new motor that do not follow.
Elevating your new rotors up to "and above" the normal operating
temperature of their optimal use is key, to their longevity. Hear me
again UP TO and ABOVE their normal operating temps. Herein lies the
difference, obviously you do not want to overheat a new motor. But
there is all sorts of evidence that engine blocks (cast iron) seems to
settle or move around during initial and extended heat cycles. It seems
very counter intuitive to what you might want do to a brand new part
but it must be done to maintain the longevity of your rotors. This over
heating event performs a bit of stress-relieving, in its intended
form/use, and surely all of
my testing supports this. Rest assured cast iron is one of the best
materials for a heat sink, and a friction deposition medium. It isn't
until you have spent more than 10 times the dollar amount that you might
decide on carbon fiber to perform the same task.
4. Elevating the rotor to the proper temperature
slowly, is key to not warping (un-evenly depositing pad material on) the
rotors. The proper temperature for this "stress relieving" is
way above the operating temperature for the pads that I supply, so
slightly over heating the rotors is what you will be doing. Fortunately I
have NEVER seen rotors actually WARP!!! What I have seen is uneven pad
deposition on untrue rotors or rotors that were heat cycled
below the maximum operating temperature for quite a while. Fortunately
in each case I have witnessed
rotors suffering from both problems, decrease "warping" symptoms after
performing a complete bed-in procedure, once trueness or the problem
with steps 1 thru 3 had been eliminated as a possible source.
5. All of the suspension components have been replaced, and you have confirmed they have no play in them.
The first customer with this problem went back and forth with me for
over 7 months. He is a competent mechanic, and owns/runs a garage and
specializes in performance vehicles. He knows them well, and has/had
installed several of our brake kits on his customers cars and his own
personal car. We had been through every possible scenario of what could
be wrong. We were both very frustrated, he was so fed up that he
purchased new rotors and rotor hats. Before shipping I had them
checked for truness, something that is normally never necessary. He
installed them on the car and the problem persisted. Obviously he
called exasperated, again we spent quite a while on the phone covering
every item in detail. When I asked about the suspension he assured me
all the pivots had been replaced. I asked how many miles on the
chassis, and he proudly stated 200K +. Then I asked, if he had ever
replaced the front upper control arms. He immediately replied "We
replaced the bushings with Urethane." I repled "No, the entire control
arm. Remember there is an outer ball joint that is integral to the upper
control arm, and not serviceable or grease-able" I knew from earlier
conversations he had factory upper control arms. There was a bit of
silence, he replied "You know, I don't think we have!?!?" A few days
later I received a 7 minute voice message, where he described in detail
how the initial diagnosis felt exactly like a brake rotor out of true,
and the pressure on the rotors under load exhibited every sign of the
rotors being out of true. Then he followed with a sincere apology for
being so convinced the problem was with our brakes. I called him back
and re-assured him no apology was necessary. We truly feel to this day
if you have a problem, we want to make it right. Please don't worry
about sparing our feelings. If you are having problems we want to make
Next we are covering the complete bed-in procedure and have performed this
countless times and it has worked flawlessly on every set. Again
raising the temperature "gradually" "consistently" is the most important
thing. Shocking a new stone cold rotor and pad set is the worst thing you
can do. First we will cover how you and I can know how much pedal
pressure is enough. This method has been documented by another
manufacturer, I do not claim to be the originator, but it works
excellent for our purposes.
Bed-in procedure definitions.
Lets say rolling down the road "NO" foot on the brakes is 0% brake pedal
force, and when applying the brakes the moment your tires lock, is 100%
pedal force (for ABS cars continuous actuation of the ABS
motors will be considered 100% pedal force) felt by a buzz or a grinding feeling at the brake pedal (I'm sure
if you have ABS you have all felt it before) so half of this pedal
pressure will be 50%. Obviously this will be different for different
tire compounds so this will not be an equal scale for cars with lesser
grip. A car with track tires (tread wear of 100 or less) will have much
more grip than a car with street tires, so 50% on track tires will slow
the same car much faster than 50% on street tires. I mention this so
that all can be aware that if you have street tires you might need to
apply a few percent less pressure than I have recommended if you don't have ABS. This is not
exact science and probably has a margin of error greater than +/- 15% so
don’t worry if you’re a little bit off. If you do most of what I
recommend you will have successfully bedded in the brakes.
For the rest of this discussion we will assume you have better than
(lower) than a 200 treadwear rating. Tires harder than 200 treadwear
without abs will surely be able to lock the tires at-will over 100 mph
with 75% less pedal pressure than it took with factory brakes (IF you
could even lock the tires with the factory brakes).
Bedding-in the rotors:
Drive thru the neighborhood/industrial complex, (a place with little to
NO traffic) use them like normal, make sure the pedal feel is as good or
better than the original brakes and makes no noise. If its not you have not properly bled the
brakes, return to the shop (slowly) and find the problem.
You might (I say "might" because it doesn't happen all the time) notice a
"whump whump whump...." during the first several pedal applications.
This is the edge of the new pads going over the edge of the new rotor
slots it will go away within the first half dozen or so pedal
applications, this is normal.
Again use as normal, getting a feel for your new brakes, stay under
35-40 miles per hour for the first dozen or so applications, just to get
the feel and to keep "slowly" increasing the temperature of the rotors.
Go to a safe place where you can stop from 60+ without fear of causing
an accident. Several customers have made new customers because their
friends that followed on the maiden voyage of their new brakes very
nearly rear ended them on just the 2nd or 3rd stop. Meaning the factory
brakes weren’t as good at 100% capacity as the Wilwoods were at 60%
while being bed-in. These brakes are more than twice as good as your
factory, brakes and you will be shocked at how effortless and
controllable they are. DON’T LET YOUR FRIENDS FOLLOW YOU IN THEIR CARS!!!
Bed-in procedure details:
First I need to cover a few DONT'S and WHYS!!!
Do not come to a complete stop with your foot on the brakes during the duration of this test
(if you can help it). i.e. once you have put a considerable amount of
heat into them if you have to stop at a light/sign, stop a few cars short and
roll/move slowly during the duration of the red light until it turns
green or you can proceed.
Coming to a complete stop with very hot pads does 2 things, it leaves a
pad imprint on the rotor, transferring an abnormally high amount of pad
material. This increased material leaves a raised area, a crystalline
and pad composite growth that you will be able to feel (at the brake
pedal) if not see on the rotor. Also if the heat is high enough and the
pressure high enough and left long enough you will in-effect "surface
heat-treat" the rotor in one area. As time goes on this harder spot
wont wear near as much as the rest of the rotor surface and as a result
this high spot will get hotter and hotter transferring more and more pad
material. This is often mistaken as WARPED rotors when in effect it is
a true and straight rotor, but the rotor develops a high spot on both
sides of the rotor. Turning the rotors seems to be the only solution.
In rare cases even turning that won't solve the problem as the
crystalline growth happens in both directions (above and below the cast
iron surface of the rotor) if drastic enough and if the lathe cut isn’t
deep enough, the high spot will reappear. Usually this is only in the
most drastic of scenarios when in extreme race conditions, street driven
rotors will usually be completely repaired by a conventional brake
If you were ever to attend a high performance driving school where they
rent you a car, you would
surely experience this problem with a majority of the cars they supply.
I have a few close friends that are/were mechanics and instructors at
I know for a fact that Bondurant, Skip Barber, (and I'm confident all
consider this to be one of the most common problems with all of their
cars, and since they have so many new students the instructors just
preach all they can and the mechanics just replace the parts when they
are so bad they are not safe.
Overview of the bed-in procedure:
short, the objective is to gradually bring the rotor/pads up to and
slightly above operating temps. Then drive around a while using little,
to no brakes, letting the rotors completely cool to ambient temps. Then
Now on to the detailed bed-in procedure:
Put a small amount of heat in the rotors from a stroll around the neighborhood (or
a warm up lap at the track) follow these instructions and you should
have completely bedded rotors.
Again find a place where you can complete these stops (intense
deceleration events) safely. Between
each stop (deceleration events) wait about 3/4 to 1-1/2 miles to let the
temps stabilize but
not cool off. More than 2 miles is too long between stops. I say
"Deceleration event" because you wont be coming to a complete stop on
any of these events.
Get the car up to 60 mph and apply the brakes with a 40%~50% effort down to
5~10 MPH. This will take a while make sure there is no one behind you.
Get the car right back up to 60 and repeat once again.
Get the car back up to 60+ mph
(no more than 3 times total)
With the car at 80 or so:
Apply the brakes at a 60%~70% effort from 80 mph down to 5~10 mph.
Repeat once again.
Again get the car up to speed again, (80 mph) and apply the brakes at 80% effort down to 5~10 mph.
Repeat once and you should be finished, if you didn’t smell brakes or
see smoke then your not done. Repeat until you know you have put too
much heat into them. This will be evident by a slight feeling of "Oh
man I think I did something wrong, the whole car feels different." This
is just the rotor at its hottest, and outside the proper temperature
range for the BP-10 pads supplied. If you are installing more
aggressive pads, at the track, just install the new pads, and (warm the
rotors/pads up gradually) perform an abbreviated version of the bed-in
process, not decelerating to such a slow speed, and this should be
The on un-coated rotors, most of the smoke is from all the oils that the
rotors are shipped in burning
off of the inside of the cooling veins of the rotor. We currently
supply all standard rotors with Wilwood's E-coating, so the brake smoke
will be slightly less. Don’t be alarmed,
if you will find 2 rings of brake dust on the inside of your clean
rims, look closely and you will notice the slots doing their job as
witnessed by several pairs of more dense brake dust trails on the inside
of the rim corresponding with where the slots routed the dust. On
un-coated rotors you will see this also, and the oils that you couldn't
remove with brake cleaner, will be flung out of the cooling veins
when they were super heated.
After you have smelled, or witness the brake smoke, do one more stop to make
sure all is consistent, then, chances are you are done. If you have
ABS, on your last few stops, (deceleration events) try STANDING on the pedal to get full ABS actuation (100%) to see
just how good the brakes work. Again a decrease in performance means
you over did it, ("got them over heated" and this is what we want) let
the brakes cool and try it again later, but you will be SHOCKED at how
good they work and how much you can abuse them. As with any brake
system, you can do damage getting them too hot for too long, as in
"riding the brakes for the hell of it or doing "brake stands" on the freeway or rolling races". But rest assured, you WILL have
to try to find that point. Your better judgment will tell you to stop
long before you have damaged anything.
If you don’t have ABS gradually work your way to more and more pressure
to find where the limit is so that you don’t "flat-spot" your tires.
Trust me its very easy to under estimate these brakes. Also if your
going to continue to run them or your track session isn’t finished,
don’t be alarmed when you feel pedal movement (what feels like a
slightly warped rotor), this is the hot rotor moving around and will
return to true once you let it cool off, just don't come to a complete
stop while they are very hot. Also try not to do this in
the rain as it might prematurely cool the rotors, or take longer to get them up to temp.
I realize some might have a track ONLY car. This can be done at the
track with no problem. Announce at the drivers meeting or, at your
session meeting that you have new brakes and you are bedding them in and
that you will stay off line if you see traffic coming. Line up at the
end of the group and go out and perform your bed-in process as close to
what has been described as possible. If you have not completed the
process and the leaders are catching you, go ahead and roll through pits
slowly and wait for the pack to pass and continue until finished.
Inform the stewards and the leaders in the group, and announcing it in
the group meeting will make all aware and keep everyone from wondering
what you are doing. Don't worry, everyone will understand, especially
when later in the day the only cars able to out brake you are the open
wheel race cars. Honestly several customers have called back (from the track) and stated
that they can out-brake every other car on the course except the open
wheel variety. When your 3000 lbs+ car can out stop cars that weigh
1/3rd less you know you are doing something right.
Do an extra cool down lap or roll around the neighborhood/industrial
complex before you come to a complete stop, make sure to let it cool
quite a bit
before you come to a complete stop. Try to use no brakes, or your
parking brakes to decelerate into your shop/garage or the pits. Let
cool to ambient or until your
next race session and you should be good.
We love to hear your
track experiences, (good or bad) if your driving home from the track and
you just gotta tell somebody, (because you know your wife or girlfriend
wont care) give us a call, we know exactly how you feel.
Thanks for purchasing our products, and feel free to contact us if you have any questions.