disk rotor choice

On Mar 18, 4:03*am, George > wrote:
> ('04 Cavalier) I need to replace the disk rotors. *Everyone hereabouts
> seems to have two varieties: one at $22-ish, the other at $38. *The $38
> ones have a longer warranty, but only for "defects". *

Spend the extra bucks to get the better rotors and good pads, then
make sure to service and adjust the rear brakes, which in all
likelihood caused the fronts to warp in the first place.
Good luck,
Ben

"ben91932" > wrote in message
...
On Mar 18, 4:03 am, George > wrote:
> ('04 Cavalier) I need to replace the disk rotors. Everyone hereabouts
> seems to have two varieties: one at $22-ish, the other at $38. The $38
> ones have a longer warranty, but only for "defects".

Spend the extra bucks to get the better rotors and good pads, then
make sure to service and adjust the rear brakes, which in all
likelihood caused the fronts to warp in the first place.
Good luck,
Ben

**********
Excellent comment. If the rears are not functioning as they should,
the mass of the braking energy will be generated at the front pads
and rotors, and damage is not only likely, it is certain.

I saw a lot of this happen when GM was selling its faulty four wheel
disc system. If you didnt do what you had to do to make sure the
rear pads adjusted themselves, not only would the parking brake not
work, but the front discs and pads would suffer.

"hls" > wrote in
:

>
> "ben91932" > wrote in message
> news:7a158d10-7402-4c00-8a54-21f28177d456
@d26g2000prn.googlegroups.com...
> On Mar 18, 4:03 am, George > wrote:
>> ('04 Cavalier) I need to replace the disk rotors. Everyone hereabouts
>> seems to have two varieties: one at $22-ish, the other at $38. The $38
>> ones have a longer warranty, but only for "defects".
>
> Spend the extra bucks to get the better rotors and good pads, then
> make sure to service and adjust the rear brakes, which in all
> likelihood caused the fronts to warp in the first place.
> Good luck,
> Ben
>
> **********
> Excellent comment. If the rears are not functioning as they should,
> the mass of the braking energy will be generated at the front pads
> and rotors, and damage is not only likely, it is certain.
>
> I saw a lot of this happen when GM was selling its faulty four wheel
> disc system. If you didnt do what you had to do to make sure the
> rear pads adjusted themselves, not only would the parking brake not
> work, but the front discs and pads would suffer.
>
>

The fronts do appx 80% of the braking anyway so unless your a very
heavy braker. the rears won`t make much diff. KB

"Kevin Bottorff" > wrote in message

>
> The fronts do appx 80% of the braking anyway so unless your a very
> heavy braker. the rears won`t make much diff. KB

If you dont keep the rears in adjustment, the fronts will have to do
100% of the braking. And that does make a difference.

On 03/20/2011 11:54 AM, hls wrote:
>
> "jim" <"sjedgingN0Sp"@m@mwt,net> wrote in message >
>> I don't know why you think single piston calipers are more modern, but
>> you are correct that sticking calipers can quickly cause a tiny amount
>> of warp to turn into a greater amount of uneven wear and warp.
>> -jim
>
> Remembering a few decades ago, a lot of calipers had dual pistons and
> some even had four (Corvette and perhaps a few others). I would guess
> that this added complexity, weight, and expense, and flew in the
> face of the rule of thumb that the more working parts you have, the more
> failures you will have.

single piston [single sided] calipers came about originally because
they're more compact on the wheel side of the disk and thus make it
easier to achieve negative scrub radius - something considered essential
for modern sedans.

http://en.wikipedia.org/wiki/Scrub_radius

frequently supposed savings in machining single sided calipers are hard
to achieve because you have to machine past the "claw", and
"reliability" is negatived by two things that don't affect older style
opposed piston calipers:

1. sticky sliders

2. a seized piston means the brakes don't work at all vs. opposed piston
where it's rare for both to be dead.




>
> I agree that one should clean the hub and the mounting face of the
> disc to be sure that there is no runout due to dirt or rust. If you
> really wanted to go down that road, you can try the rotor disc at
> all five possible mounting positions and test the runout with a dial
> indicator. I've never done this, but may take the time, if I ever have
> to work on my own brakes again.
>
> I've seen the ventilation channels get pretty dirty or rusty, but I never
> took the time to clean them. Have you? Agreed that if you are going
> to use cheap rotors, it might be easier just to buy new.
>
> It is beginning to look like most brake mechanics these days are parts
> changers, and many have no idea nor really care what makes the rotors
> wobble. Not that parts changing is bad, mind you. It can
> sometimes be the cheapest, quickest, and surest cure.


--
nomina rutrum rutrum

On Fri, 18 Mar 2011 07:03:05 -0400, George >
wrote:

>('04 Cavalier) I need to replace the disk rotors. Everyone hereabouts
>seems to have two varieties: one at $22-ish, the other at $38. The $38
>ones have a longer warranty, but only for "defects".
>
>My guess is, the $38 ones are 'better' (more metal?); but, it could be
>just charging more for a pretty meaningless warranty. Does anyone know?
>
>Thanks,
>George

I've had genuine FORD rotors warp in 4000 miles of normal driving. And
the cheap china rotors go 20K without warping. I think it's mostly a
crap shoot. I did notice the last time I bought cheap rotors that one
of the ones they gave me had a crack in it near the hub and had them
get me a different one. I don't think there is much difference in the
amount of metal but there can be a difference in how the cooling vents
are made, the size and spacing and angle. Probably doesn't matter if
all you do is commute but if you regularly drive in mountainous
terrain it might cause greater heat build up in the cheap ones.

On Sat, 19 Mar 2011 08:01:19 -0500, "hls" > wrote:

>
>"dsi1" > wrote in message
...
>>> There are several factors at work here.
>>
>> My guess is that most car guys won't believe it.
>
>Im sure you are right.


Do you wash your new rotors in soap and water as the makers of the
rotors say is mandatory?

"Ashton Crusher" > wrote in message
...
> On Sat, 19 Mar 2011 08:01:19 -0500, "hls" > wrote:
>
>>
>>"dsi1" > wrote in message
...
>>>> There are several factors at work here.
>>>
>>> My guess is that most car guys won't believe it.
>>
>>Im sure you are right.
>
>
> Do you wash your new rotors in soap and water as the makers of the
> rotors say is mandatory?

I do wash them to get the rust preventative grease off of them. I have
also used brake cleaner (largely methanol) in the past.

"Ashton Crusher" > wrote in message
...
>
> I've had genuine FORD rotors warp in 4000 miles of normal driving. And
> the cheap china rotors go 20K without warping. I think it's mostly a
> crap shoot.

When you had the problem with the Ford rotors, was there any
particular factor that you thought might have caused their early demise?

On several occasions, I have had rotors warp after having wheels
rotated. These rotors had a year or two on them with no problem,
but developed the warp within 2-3 weeks after the wheels were
rotated and installed with an impact wrench and tork stix.

On 03/22/2011 02:50 PM, hls wrote:
>
> "Ashton Crusher" > wrote in message
> ...
>>
>> I've had genuine FORD rotors warp in 4000 miles of normal driving. And
>> the cheap china rotors go 20K without warping. I think it's mostly a
>> crap shoot.
>
> When you had the problem with the Ford rotors, was there any
> particular factor that you thought might have caused their early demise?
>
> On several occasions, I have had rotors warp after having wheels
> rotated.

that's typical.


> These rotors had a year or two on them with no problem,
> but developed the warp within 2-3 weeks after the wheels were
> rotated and installed with an impact wrench and tork stix.

if you do the scrape, anti seize and proper torque thing, you'll find
your rotors are probably not warped permanently, just distorted by bad
seating and incorrect torque.

and tork stix are not a good choice. they make presumptions about the
impulse from the air tool - if the input is not per that presumed, the
output isn't either.


--
nomina rutrum rutrum