Date: Tue, 17 Aug 2004 07:33:45 -0700
Reply-To: Robert Fisher <refisher@MCHSI.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Robert Fisher <refisher@MCHSI.COM>
Subject: Re: Rotor thoughts
Content-Type: text/plain; charset="iso-8859-1"
Yup. Those're some messed-up rotors.
Might've been helpful to see the contact surface of the pads, if you get
around to it. The wear pattern on the insides is only 40-50% as wide as the
outside, and not even the same size as each other... bizarre. Still looks
like an operational problem, tho.
Seeing that reminds me of the upsides to living in California.
Cya,
Robert
----- Original Message -----
From: "Eric Zeno" <vw4x4@FYI.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Tuesday, August 17, 2004 4:25 AM
Subject: Re: Rotor thoughts
> "a picture would resolve that issue very easily"
> You got it!
>
> http://www.fyi.net/~vw4x4/in1.jpg
> http://www.fyi.net/~vw4x4/in2.jpg
>
> Here is 2 pictures of the inner side of the rotors
> http://www.fyi.net/~vw4x4/out1.jpg
>
> Here is the outer side. You can see they are not as bad
> but still have had rust biuld up on them.
>
> http://www.fyi.net/~vw4x4/pads1.jpg
>
> Here is the pads in not particular order. Look close
> you can see there is plenty of meat on them.
>
> As you stated below in more techincal terms
> than I want to understand, I thing the rotors are the problem.
> Unfortuneately I've gotta to get to work.....
> ERic
>
> Kim Brennan wrote:
>
> > That's not true. You don't have to do a chemical analysis of the metal
> > (which actually will likely give you very little information of value
> > anyway). Of far more importance when dealing with metal is the
> > crystalline structure.
> >
> > The crystal structure can reveal flaws that will lead to failure. It
> > can reveal nonhomogenous composition. Depending on the nature of the
> > material crystal structure can sometimes be revealed by patterns.
> > Analysis of meteorites, for example is done by polishing the surface
> > and then etching with acid. In industrial applications spectroscopic
> > imaging tends to be used. Rotors being cast, should have a crystal
> > lattice that is revealable. Forged metals tend to reduce the size of
> > the crystals (removing the gaps in the crystalline structure, and
> > improving the strength of the forged material.)
> >
> > You have continued to claim that your rotors are "bad", without
> > describing that nature of the problem (other than "rust", which is
> > perfectly normal on rotors.) Are the rotors warped? Are they cracked?
> > Are they out of balance? If so how did you determine they were out of
> > balance? Wear patterns can often times be extremely illuminating, hence
> > why pictures are valuable.
> >
> > While state inspections vary, most places are concerned with.1) Do the
> > brakes work? 2) Are the materials within tolerances? 3) And are the
> > materials up to the standards of the day (not necessarily TODAY's
> > standards, but the standards of the original manufacture date of the
> > vehicle.) Tolerances are measured (hence the micrometer measurements.)
> > Standards for the rotor are usually resolved by visual inspection.
> > Hence the need for a picture.
> >
> > If your rotors are rusty on either wear surface after having driven the
> > vehicle to the end of the block and back. The Rotors are probably NOT
> > the problem. The calipers and pads need to be checked out. The pads
> > should be in contact with the rotor. The caliper should move back and
> > forth. The piston should respond to the brake pedal.
> >
> > On the other paw, if you have rust cracks WITHIN the rotor (as opposed
> > to just on the surface), that could be a sign of a faulty rotor. Again,
> > a picture would resolve that issue very easily.
> >
> >
> > On Aug 16, 2004, at 3:27 PM, Eric Zeno wrote:
> >
> >> The only way to tell if the manufacture cut corners
> >> in the alloy in the materials is to do a chemical analysis
> >> of the material. Obviously I'm not going to do this.
> >
> >
> >
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