Some may find it interesting that brake discs are sometimes turned right
on the car,
using the car's engine and trans to turn the disc,
for two reasons generally I think..
Brake discs are 'captured' on some FWD cars so they don't come off
easily, like without taking the front wheel bearings/hub area apart ..
and ...it can deliver a better, more true result..
turning it right onthe car , in place.

Honda's are typically done that way, forexample, especially at dealerships.

'turning rotors' ..
and drums...getting that done really right is not 'automatic' at all.
   I have one guy ...been a machinist and parts store owner and hot
rodder 'forever' ..
and I think he's using decent equipment and doing the very best he can ..
and yet ..
if I rig up a rotor to check run-out with a dial gauge after getting it
turned ...I'm still finding it's not that true ..
off by a few thousandths, like under .005, but still not really true
running.
   I generally just replace them these days with new 'uns.'
and well-made ones, like European-made.

Let us know how your front brake job turns out.
I always change the brake fluid to any wheel I work on at all.
Ijust cringe when people or shops do pads n' rotors and leave the old
brake fluid in .

On 9/20/2013 12:14 PM, Edward Maglott wrote:
> This machine was turning both sides at the same time and it was easy to
> stop it and see that the high areas on one side perfectly matched the low
> areas on the other side.  I'll have to ponder this in my head for a while
> to think of ways that the disk is not "warped" but has high and low areas
> that correspond....
> Edward
>
>
> On Fri, Sep 20, 2013 at 2:15 PM, Tom Hargrave <thargrav@hiwaay.net> wrote:
>
>> You read the machine right and I've seen the same thing when I turned
>> rotors.
>>
>> My "opinion" based on what I have observed, what I know and the article we
>> both read is that "warped rotors" are probably rotors that are just thinner
>> in some areas than others. And since rotors are turned one side at a time
>> there is no way to correlate the observed warping with thinner & thicker
>> areas.
>>
>> Thanks, Tom Hargrave
>> www.kegkits.com
>> www.stir-plate.com
>> www.towercooler.com
>> www.grow-sun.com
>> www.raspberryproject.com
>>
>> -----Original Message-----
>> From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM] On Behalf Of
>> Edward Maglott
>> Sent: Friday, September 20, 2013 1:05 PM
>> To: vanagon@GERRY.VANAGON.COM
>> Subject: Re: Why Bigger Brakes Was Cause of brake rotor warping
>>
>> Hey, I got my warped rotors turned!  The auto tech instructor at the
>> college
>> where I work let me watch while the first one was running.  You could see
>> by
>> looking at where the cutters were taking material off the disk that it was
>> warped.  By warped I mean the places the cutter was removing material on
>> one
>> side was the opposite of where the cutter on the other side was removing
>> material.  By opposite I mean around the circumference of the disk.  Like
>> at
>> 12 o'clock vs 6 o'clock.  The article linked earlier seemed to indicate
>> this
>> was very very rare.  Or did I not read that right?
>>
>> Edward
>>
>>
>> On Sun, Sep 15, 2013 at 3:24 PM, Dave Mcneely <mcneely4@cox.net> wrote:
>>
>>> Jacobson Brakes, the company that made them popular.
>>>
>>> ---- Loren Busch <starwagen@GMAIL.COM> wrote:
>>>> RE: Compression Braking devices or "Jake" Brakes Trivia question for
>>>> this thread:  Where does the term "Jake Brakes"
>>>> come from?  No Wiki now, I'll check with NSA to see if you cheated.
>>>> First person with the right answer gets 100 points that can be used
>>>> for whatever that person wants :)
>>> --
>>> David McNeely
>>>
>>