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From: SMS on 24 Sep 2009 01:12
Ray O wrote:
> "Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote in message
> news:h9e3qk$3ag$1(a)news.eternal-september.org...
>> "Hachiroku ????" <Trueno(a)e86.GTS> wrote in message
>> news:pan.2009.09.23.21.18.08.124947(a)e86.GTS...
>>>> Rear Drum brakes self-adjust by using the parking brake? Are you sure?
>>> On my 2 Tercels. Pulling the e brake (parking brake?) lever actuated the
>>> adjusters.
>>>
>>
>> Hmmm ...
>>
>> I've never heard that before. I musta been sleeping.
>>
>
> Wake up! Hachi is correct.

That's not something you can say very often!
From: SMS on 24 Sep 2009 01:42
Ray O wrote:
> "Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote in message
> news:h9duqo$lrr$2(a)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.
From: Ray O on 24 Sep 2009 02:16

"SMS" <scharf.steven(a)geemail.com> wrote in message
news:4abb0680$0$1588$742ec2ed(a)news.sonic.net...
> Ray O wrote:
>> "Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote in message
>> news:h9duqo$lrr$2(a)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.

The disc thickness variation is what is causing the pulsation when the rotor
gets hot.

If engine braking is not sufficient, try dropping down one more gear range,
and instead of riding the brakes, try giving them a good stab to bleed off
speed, then let the speed build up a little, then give it another stab. The
time between brake applications allows the rotors to cool a little.

I've driven on Old Priest Grade and also coming down Donner Pass. The lower
gear range and stabbing the brakes works.
--

Ray O
(correct punctuation to reply)


From: someone on 24 Sep 2009 02:36
In article <h9e3qk$3ag$1(a)news.eternal-september.org>, "Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote:
>
>"Hachiroku ????" <Trueno(a)e86.GTS> wrote in message
>news:pan.2009.09.23.21.18.08.124947(a)e86.GTS...
>>>>
>>> Rear Drum brakes self-adjust by using the parking brake? Are you sure?
>>
>> On my 2 Tercels. Pulling the e brake (parking brake?) lever actuated the
>> adjusters.
>>
>
>
>Hmmm ...
>
>I've never heard that before. I musta been sleeping.
>
>
>
>
>
>
that wasn't the case on my 86 2/4, it had the backup adjusters.
either that or the diety of brakes tightened them then.
From: Hachiroku on 24 Sep 2009 12:23
On Wed, 23 Sep 2009 22:12:17 -0700, SMS wrote:

>>> I've never heard that before. I musta been sleeping.
>>>
>>
>> Wake up! Hachi is correct.
>
> That's not something you can say very often!


Well, more often than not!

No one is ever really correct with politics.
And I try to be when it comes to cars!

As I said, I'm not familiar with the trucks as well, and I never had to do
the rears on my '85 2 wheel drive truck, but all the cars I've done the
rear drums on, the adjuster works with the brake handle

Your mileage may very...


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