Normally, and I hope most other shops do this as well...you measure the
runout and thickness of the rotor. You subtract .030" (max if they're
really warped) from the actual thickness of the rotor and compare to the
minimum thickness specification. If it's at minimum with that calculation,
it's up to the customer if they want to replace them. If it's below, time
to replace them...if it's still above minimum, resurface them. Rotors can
normally be turned at least 3 times unless you don't pay attention to the
signs of brakes that are worn out (squealing from the pad thickness
indicators) or even let them go metal-to-metal.
You can tell when the rotors have been resurfaced though - look for the
clean surface and the proper crosshatch. It'll be noticeable for at least
50 miles. If they didn't do it, report them to the BBB and ask for your
money back.
I've seen anything from rough sand paper marks to scotch-brite wheel marks
on the rotors. People who "resurface" or "de-glaze" them with sand paper or
a wheel shouldn't be working on vehicles. It causes more harm than you'd
think. Heck, I've even had a Durango come into the shop with grease on all
4 rotors (yes, on the rotors!) because the customer complained about them
squealing. So...the shop (or whoever did it) greased up the rotors.
Yup...no more squealing but also no more brakes. I've also seen P/S fluid
in the reservoir which was a $1200 mistake on the "quick lube" shop - wheel
cylinders, master, ABS, and calipers.
- Bernd
-----Original Message-----
From: jon@dakota-truck.net [mailto:jon@dakota-truck.net]
Sent: Wednesday, August 13, 2008 4:52 PM
To: dakota-truck-moderator@bent.twistedbits.net
Subject: Re: DML: Ball Joints & rotors
"Don Rey" <radon220@gmail.com> wrote:
> I'm with Jon in that I'm also a self-described cheapskate. I only took
> rotors in to be turned once in my life, and they sent me away because
> the rotors were below spec. Well, this was on my Dart, which gets
> <2000 miles/year of drive time, and 5 years later I'm still using the
> same rotors (and pads, which I replaced at that time). They have
> plenty of meat left and are in no danger of falling apart.
Exactly. :-) Thanks, Don; cheapskates unite! I hope my earlier
post didn't give the impression that I'm doing anything unsafe - if
there was any question in my mind as to the capabilities or safety of
the rotors, I'd swap 'em out in a heartbeat. I have a feeling though
that when most folks are told their rotors are shot and/or need to be
turned, there is a heck of a lot of life left in 'em. Possibly it is
due to being overly cautious, but I suspect that a larger incentive
for the shop is the extra money they can make by selling a new set of
rotors or turning the existing ones (wether they need it or not), or
selling rotor "turning" to an unsuspecting dupe where the carbide
never touches the steel and the only thing they've physically turned
is a tidy profit. (On a related note, that last method of turning
also greatly lengthens the life of your lathe tooling.) ;-)
> I put my current rotors on shortly before the 06 Daktoberfest. When I
> got back home afterwards, I took a look and found some of the biggest
> grooves I'd ever seen on my vehicles (I imagine the result of foriegn
> objects. see also: stiegermud).
Hehehe! You're welcome. :-) Just tell people that you've got
extrudehoned brake rotors. ;-) ("These are speed grooves; they make
it go faster.") Perhaps I should start billing BBQ participants for
the heretofore free rotor slotting service? ;-)
> With the "roads" I drive, if I have to
> turn my rotors every time I have grooves, I'll go broke. And I should
> probably keep a spare set to rotate in and limit down-time!
A little drywall spackle will take those grooves right out. ;-)
--
-Jon-
.- Jon Steiger -- jon@dakota-truck.net or jon@jonsteiger.com -.
| '96 Kolb Firefly, '96 Suzuki Intruder, Miscellaneous Mopars |
`-------------------------------- http://www.jonsteiger.com --'
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