[DeTomaso] Pantera L 4 Sale
Asa Jay Laughton
asajay at asajay.com
Fri Apr 19 10:07:49 EDT 2013
There are two seals working in this system.
One is the square-cut o-ring around the piston in the caliper. This is
(typically) engineered to flex a little bit so that after brakes are
released, the tension on the square-cut seal pulls the piston back to a
resting position; usually only a few thousands of an inch. Applying the
brakes uses enough pressure to overcome this slight tension and allow
the piston to continue moving outward to take up the necessary slack due
to wear of the pads and the disc.
However, the pedal return is (typically) not enough to overcome the
square-cut seal tension to pull the piston back into the caliper, but it
can.
The master cylinder is (typically) built with a much lighter duty
one-way lip seal. When the brakes are applied, the lip seals against
the bore of the master and applies pressure to the fluid once it passes
the feed orifice. When the brakes are released, the lip seal tension is
(typically) less than the square-cut o-ring tension in the caliper, so
fluid is drawn in from the reservoir past the lip seal; meanwhile the
piston in the caliper only moves back against the tension of the
square-cut seal enough to create minimal clearance between the brake pad
and disc.
That's the way it's "supposed" to work.
Therefore, if the brake pads are releasing "too far," there may be
something wrong in the system or the design isn't the best. I'm sure
it's true that for whatever reason, some systems tend to pull the piston
back into the caliper too far. I couldn't say why. It would appear the
residual pressure valve such as what Mike Drew and a few others are
familiar with, helps reduce whatever the problem is in the system to
prevent too much play.
I think (my personal opinion) in Mike's case, the RPV is what
contributed to massive and premature wear of the brakes. However, I
also think his thoughts about adding cooling will probably give him the
most bang for the buck to overcome the limitation he discovered on the
race track recently without compromising the street driving safety he's
used to. (not that Mike drives much differently on the street) :)
An interesting experiment for Mike to try after he's married, is to
remove the RPVs for a couple weeks to see if there is any difference; to
see if he ends up with way too much pedal travel or not. I would not of
course recommend going to the race track during that time.
Asa Jay
Asa Jay Laughton, MSgt, USAFR, Retired
& Shelley Marie
Spokane, WA
******************************
http://www.racingagainstautism.com
http://www.teampanteraracing.com
http://facebook.com/racingagainstautism
On 4/18/2013 11:07 PM, The DeTomaso Registry Guy wrote:
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> Anyone know this car?
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> http://monterey.craigslist.org/cto/3662449243.html
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> Chuck
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