XPost: alt.autos.toyota
From: scharf.steven@geemail.com
Ray O wrote:
> "Jeff Strickland" wrote in message
> news:h9duqo$lrr$2@news.eternal-september.org...
>> I'm confused.
>>
>> Once the rotors warp, they remain warped until they are machined or
>> replaced. Warping is not a transient condition where the experience is on
>> a mountain road but not on other roads. And, braking on a mountain road
>> should be lighter and more evenly applied on a mountain road than in other
>> places. The brakes might be used more often, but the braking ought not be
>> "harder". It you are driving into a turn and mashing the brakes, your
>> passengers are probably on the verge of puking.
>>
>> Having said that, slots and crossdrilling are done to help extract heat.
>
> Not quite. The slots and cross drilling on the rotors allow the gases that
> the pads generate when heated to escape more easily. If the gas can't be
> cleared from between the pad and rotor quickly enough, the effect is kind of
> like an air hockey table, reducing the contact between the pad and rotor and
> creating brake fade. The slots in some pads serve the same purpose.
Obviously I can't see what's happening, but it feels like the brakes
chattering against the rotors. I never notice it in normal freeway
driving where the brakes are lightly used, but coming down a steep grade
(like Old Priest Grade road near Yosemite) where the grade is up to 14%
and engine braking isn't sufficient, I feel it.
Supposedly this is referred to as disc thickness variation. "As the
rotor gets hot, it is much more likely to increase thickness variation,
thus increasing pedal pulsations as well as steering wheel and other
vehicle vibrations." Of course I read this on a web site that also
promotes Amsoil, so I don't know how true it is.
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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