In article <ziCsm.180519$O23.92550 (AT) newsfe11 (DOT) iad>,
dsi1 <dsi1 (AT) humuhumunukunukuapuapa (DOT) org> wrote:
New cars sometimes get damaged and sent to local auto body repair shops
for repair.

--
------------------------------------------------------------------------
Timothy J. Lee
Unsolicited bulk or commercial email is not welcome.
No warranty of any kind is provided with this message.

Timothy J. Lee wrote:
That's a bummer! I guess that would be a dirty little secret of the
automobile industry.

On 09/18/2009 01:23 PM, dsi1 wrote:
classic symptoms. google the honda groups for past discussion and my
experience before and after wheel shop work.


use a flat scraper. don't forget the inside of the wheels and the
antiseize. and don't use too much, just a little to color the surface
where the disk and wheel touch only.

On 09/18/2009 06:35 AM, hls wrote:
but that almost never happens. even if you get those disks cherry red,
you'll have a real hard time warping them.


the symptoms are a real issue. it's caused by elastic distortion [as
opposed to permanent warping] of the hub interface and incorrect torque.
if the interface is sticky because of rust, the wheel doesn't seat
completely flat, and so when incorrect torque is applied, differential
stress on a modern lightweight hub causes it to be sprung slightly off
center. if you remove, clean and slightly lube the interface, it seats
square and "warped" disks are magically square again. which is of
course why you can remove a "warped" disk and put a micrometer on it to
find it perfectly flat.


or crud patches on the disk, say from prior greasy fingerprints.

On Fri, 18 Sep 2009 16:08:59 -1000, dsi1
<dsi1 (AT) humuhumunukunukuapuapa (DOT) org> wrote:


My Dad left one of his rear doors open on his car and backed out of
his garage. The door caught the side of the garage and got pulled out
past the normal open position. the door was damaged to the point of
needing to be reskinned. Instead of fixing it (estimate was $2800) he
traded it in on a new one. The dealer fixed it but of course since
it's done by their own shop and not thru insurance there is no record.
When we looked at the ad they ran that had the car in it they had the
carfax report which highlights "No accident history" . I'm sure the
same happens on new cars that get damaged in transit or on the lot.

dsi1 wrote:
It's hardly a secret.

Brian Smith wrote:
In what way is this not a secret? Do cars typically get into accidents
on the way to the dealer? How many new cars have to have body repairs
done? If everybody knew this, wouldn't all buyers be checking new cars
for collision damage and bodywork? Are they doing this?

If might not be a secret to you if you're in the new car sales business.
If it is true, I would guess that the new car dealers would want to keep
that knowledge away from the general public - that's my definition of
dirty-little secret.

dsi1 wrote:
As the vehicles are loaded and unloaded off the ships and rail cars
bumps and dings occur in the natural course of that movement. The number
would vary depending on the season, slippery conditions would obviously
lead to an increase in damage. Note that I am taking about minor
collisions that result in small amounts of damage to the vehicle(s),
although sometime fenders, doors and bumpers have to be replaced and
painted. That's why Autoports have their own body shops. Smart shoppers
realize that this is possible and check their potential new vehicle over
carefully before accepting delivery.

I don't work in the automotive industry, I am not a novice when it
comes to the car purchasing game. It doesn't take long to drive past a
car lot and see vehicles being bumped by the car lot jockeys. Again,
it's not a secret any more than the sun rises in the east is one. :^)

"jim beam" <me (AT) privacy (DOT) net> wrote in message

I have seen it happen rather frequently.

I have gotten discs cherry red before when they didnt warp. And I have
had them warp on the vehicle within a month or two of having them rotated
when no severe overheating was evident.

The rotation didnt cause the problem directly. But the normal heating of
the rotor disc, being quenched with rain water perhaps, coupled with the
use of impact wrenches to hammer the lug nuts on seem to be the factors
that cause this.

When you can measure the warp, either on the car or on the brake lathe, then
you HAVE warp.

I fully agree that corrosion, dirt, etc can cause problems with out of
planar
rotation. When the disc rotates out of plane, it does not cause the same
sort of pulsation that is noted with width variation of the rotor occurs.

Bottom line, IMO, it is a little more complicated problem that a lot of
people
suspect. To get the best results, the mechanic or home mechanic needs to
understand the various factors that are happening., and needs to be careful
how he or she remediates those factors.

On 09/19/2009 07:56 AM, hls wrote:
you've seen the symptoms of the braking problem, but i'll bet you
haven't seen [or measured] actual disk warpage.


precisely my point!


latter, not the former.


indeed, but it's rare. accurate measurement is rare too.


with single piston calipers, it's almost impossible to tell the
difference.


indeed. that is why i'm taking the time to write about what causes and
fixes the problem. sure, you can replace the disks, a shop favorite,
and it works because the new disk surface is clean! but skimmed disks
rarely work because the disk is not cleaned.

bottom line - i have cured "warped" rotors on multiple cars multiple
times as i describe. most times i've taken a car to tire shop, i have
this problem as i drive home. i re-seat [as described] and re-torque
when i get home, problem disappears. that simply couldn't happen with a
genuinely warped disk.