[Shotimes] Front Rotor Warping
Ian Fisher
ianf@eden.rutgers.edu
Mon, 21 Apr 2003 12:06:20 -0400
Thanks for the post. You have pretty much confirmed that I have a
sticking piston in one on my wilwoods or I have severe run out from
something. I have grooves, hard spots and hot spots on my rotors and the
vibration is terrible. I have to remove them this week and figure out
which size pistons I have and order new seals to rebuild the calipers.
Either that or get new calipers. I am probably over heating the fluid as
well which might be related to my poor pedal response issue too. I found
a cheap master cylinder that I am jumping on, but I am going to look to
my front calipers first.
Ian
-----Original Message-----
From: shotimes-admin@autox.team.net
[mailto:shotimes-admin@autox.team.net] On Behalf Of Leigh Smith
Sent: Monday, April 21, 2003 11:39 AM
To: Jim and Debbie Leyden
Cc: Shotimes@Autox.Team.Net
Subject: Re: [Shotimes] Front Rotor Warping
Jim;
Have been reading your brake rotor woes with some interest. Let me see
if I have the facts straight: 93 MTX, 11.6 rotors, NAPA / Powerslot
rotors, OEM ? pads (@ FPS), break-in procedure.
Honestly, I can't figure why you would be having problems with that
setup either. It almost seems as if we're missing something.
You could be driving like a maniac and overheating them, but that
doesn't seem too likely.
It sounds like the pads are overheating, either because of a sticking
caliper / pin issue, or cheap pads that don't like the temps they are
being exposed to. Auto part store "OEM" pads ARE NOT GOOD ENOUGH. Or you
got cheap rotors that don't like the temps they are being exposed to.
You could be ruining the rotors by overheating the PADS during the
breakin procedure. The Breakin procedure accompishes two things, it
breaks in the pad, at the lower temp that they like, and it heat cycles
the rotor at a much higher temp, like 600F up. If you have cheap pads
on, they will overheat during the rotor heat cycling and may ruin the
rotors. Motto: buy great pads, or heat the carefully, not too hot, stay
below the "smell zone".
Are you sure the pads are Ford OEM in the proper larger pad size? The
FORD OEM pads are much better than part store OEM pads. Honestly, I
can't believe FPS would use anything else, but things happen.
The rotors could be cheap forgings. If they are cooled too quickly they
may take a differrent set after you heat them. And it costs too much for
the factory to let them sit around and cool slowly. You could
alternatively: A) Buy a better set B) Heat treat them in your oven (I'm
serious) C) Heat treat them by getting them hot during the breakin
procedure. Easier and better than the oven. You may have to have them
cut immediately afterward though if they warp due to cheap metal. D)
Have them cryogenically treated (even better).
Once the rotors develop hard spots in the metal from localized
overheating (feels like vibration) you can probably never truly grind it
off. It's usually too deep. New rotors are the only real cure unless you
catch it early. Blanchard grinding will help, but the hard spots may
remain.
Cheap pads are like death to rotors on these cars. There is just too
much weight and pressure on the front rotors. I only recommend some
carbon mettallic based pad. Some have had good luck with OEM w/ 11.6 in.
but they must be the FORD pads, ask to see the box. Semi-mettallic pads
(like the Ford ones) are very marginal. Part store pads can easily ruin
your rotors during the break-in procedure, or anytime you use them
really hard.
Given your history of problems, I'd recommend the following:
Borrow my infrared pyrometer if you want and make sure you don't have
some strange sticking caliper/pin issue that is getting your rotors past
600F. That's the normal "smell zone". You really don't even need the
pyrometer, it just might make you feel better. If they are getting that
hot, you can easily smell them, and it is not a pretty smell. The
pyrometer or lack of smell should confirm that your brakes rarely get
past 400F. That would rule out maniac driving and caliper issues. If
that is so, you should be fine with the Ford pads, and you have got
another issue, not a mechnical one.
Also monitor the temps in this manner during your "breakin" procedure.
Don't get them realy smelly unless you have really good pads on.
Buy some inexpensive Perfomance Friction Carbon Mettallic Pads first
($30?). You can't overheat them, they'll take 800-1000F without ruining
your rotors in the process.
Have the existing rotors turned or blanchard ground at the same time.
Break them in, just to the point of smelling them. Don't go overboard
here. If you stick with FORD pads, I'd skip the breakin step entirely.
If localized hard spots remain in the old rotors the vibration may
return over time.
Then buy brand new good quality rotors as step two, making sure you have
good pads and the rotors are not getting too hot first. You don't want
to risk damaging the new rotors again.
Stay away from slots /holes.
Get them cryogenically treated if you want, but I can't believe you need
it. Not even for track events, but it is good insurance. I'd rather see
you buy some carbon pads.
If you don't like the dust from the PFC pads, buy some better and more
expensive carbon pads later. Carbotech, Porterfield or Raybestos Quiet
stop ceramic.
There is no reason following this procedure shouldn't solve your
problem. Just ask Josh, he was killing rotors and it turned out he had
cheap pads after all, and they didn't like the heat.
Auto part store OEM pads ARE NOT GOOD ENOUGH for our SHOs, at least not
all of us anyway.
Good Luck
Leigh
Jim and Debbie Leyden wrote:
> I bought the OEM pads from FPS at the same time I put the first set of
> rotors on. I drove the car carefully (using the brakes only lightly)
> for the first week. Then I went out and performed the breakin
> procedure that is outlined on that website. I even went to the
> extreme of printing out the instructions and taking them in the car
> with me while I did the breakin. At no time did (or do)I EVER sit in
> traffic with hot brakes and keep the brakes applied hard. (if the car
> will sit at a light in neutral without rolling that is what I do. If
> it won't, I will let it slowly creep with the brakes barely applied so
> the pads can't burn to the rotor) I have inspected the rotors
> visually and I can see no evidence of friction material transfer on
> the rotors.
>
> Like I said... we have been extremly careful with this set of rotors
> to not mess them up.
>
> Another thing that is bothering me is the act of having the rotors
> turned by a service center. Being a former machine tool builder I
> understand all facets of manufacturing processes and I firmly believe
> that the act of turning a rotor is destructive to the friction
> surface. I would like to get them Blanchard ground using the hubs
> mating surface for the baseline but I have no clue as to where I could
> find a machine shop around the Atlanta area that could tackle this.
>
> Jim
> '93 MTX
>
>
>
> -----Original Message-----
> From: Paul Nimz [mailto:pmnimz@V8SHO.com]
> Sent: Saturday, April 19, 2003 3:47 PM
> To: Jim and Debbie Leyden; Shotimes@Autox.Team.Net
> Subject: Re: [Shotimes] Front Rotor Warping
>
>
> What kind of pads do you use? Do you seat the pads after a 100 miles?
> Read this for a controversial opinion.
> http://www.stoptech.com/whitepapers/warped_rotors_myth.htm FWIW on my
> '97 with the OEM rotors and 90k they didn't warp. And now with AZ
> rotors still no problem. I have only used the OEM pads and am very
> pleased with them.
>
> Paul Nimz
> '97 TR SHO
> '93 EG mtx SHO
>
>
> ----- Original Message -----
> From: "Jim and Debbie Leyden" <jndleyden@mindspring.com>
> To: "Shotimes@Autox.Team.Net" <shotimes@autox.team.net>
> Sent: Saturday, April 19, 2003 1:08 PM
> Subject: [Shotimes] Front Rotor Warping
>
>
>
>>A little over a year ago I upgraded my brakes to the 11.6 front
>>rotors. When I did the conversion I used new pads, rotors, brackets,
>>slider pins, calipers and backing plates. The knuckles were purchased
>>from a boneyard. About six months ago the car started to vibrate when
>>braking. I checked
>
> the
>
>>front rotors and found that there were casting porosities in them. I
>
> talked
>
>>to the place where I purchased them and they agreed to credit me the
>>cost towards a set of PowerSlot rotors. Well, now six months later I
>>again
>
> have
>
>>a nasty vibration from the front end when braking. My wife and I have
>
> been
>
>>VERY careful with these brakes so as to not overheat them. (I DO drive
>>rather hard but I use engine braking as well as brakes) I talked to
>>the shop where I purchased them and was told that the same situation
>>had
>
> arisen
>
>>with the owners car (powerslots also) and he merely had to take them
>>out
>
> and
>
>>REALLY heat them up to correct the problem. I tried this, it seemed
>>to
>
> work
>
>>for a little while (couple weeks they were fine) but now the shaking
>>is
>
> back
>
>>and even worse then before.
>>
>>Any clues as to why I can't keep a set of rotors from warping?
>>
>>Jim
>>'93 MTX
>>perfect for that commercial where the guy is shaking his chocolate
>>milk. _______________________________________________
>>Shotimes mailing list
>>Shotimes@autox.team.net http://www.team.net/mailman/listinfo/shotimes
>
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