"Tom" <tom_christensen(snabela)bigfoot.com> wrote in message news:<42cac11c$0$182$edfadb0f@dtext01.news.tele.dk>...
> Den bremser bedre med riller fordi der opstår en gas mellem skive og klodser
> som bedre kan undvige med riller og derfor skabe bedre kontakt.
> Når det regner, så vil rillerne også være med til at fortrænge vand fra
> skiverne.
Den med gassen skriver de fleste "racerbremse" firmaer er et lævn fra
gamle dage, da der var asbest i klodserne. Ved moderne kloser er
problemet yderst minimalt hvis det over hovedet er der. Alle de
"seriøse" bremsefirmaer jeg har set, skriver at det idag er mere eller
mindre "bling-bling", uden praktisk betydning. Alt sammen skrevet af
firmaer som selv laver skiver med huller/riller. Et par eksempler:
Wilwood brakes:
"Rotors are drilled to reduce rotating weight, an issue near and dear
to racers searching for ways to minimize unsprung weight. Drilling
diminishes a rotor's durability and cooling capacity.
Slots or grooves in rotor faces are partly a carryover from the days
of asbestos pads. Asbestos and other organic pads were prone to
"glazing" and the slots tended to help "scrape or de-glaze" them.
Drilling and slotting rotors has become popular in street applications
for their pure aesthetic value."
(
www.wilwood.com/Centers/Information/question_answer/07.asp )
Baer brakes:
"In years past, cross-drilling and/or slotting the rotor for racing
purposes was beneficial by providing a way to expel the gasses created
when the bonding agents employed to manufacture the pads began to
break down at extreme temperatures. This condition is often referred
to as "green pad fade" or "outgassing". When it does occur, the driver
still has a good firm brake pedal, but simply little or no friction.
Since this normally happens only at temperatures witnessed in racing,
this can be very exciting!
However, with today´s race pad technology, ´outgassing´ is no longer
much of a concern. When shopping for races pads, or even ultra-high
performance road pads, look for the phrases, "dynamic surface
treatment", "race ready", and/or, "pre-burnished". When these or
similar statements are made by the pad manufacturer, the pad in
question will likely have little or no problem with ´outgassing´.
Ironically more pedestrian pads used on most streetcars will still
exhibit ´outgassing´, but only when used at temperatures normally only
encountered on the racetrack.
Although crossdrilling and/or slotting will provide a welcome path to
expend any gasses when and if they develop, it is primarily a visual
enhancement behind today's often wide-open wheel designs.
Crossdrilling offers the greatest gas relief pathway, but creates
potential "stress risers" from which cracks can occur. Baer´s rotors
are cast with crossdrilling in mind, from the material specified, to
curved vanes, behind which the holes are placed to minimize potential
crack migration. Slotted surfaces are what Baer recommends for track
only use. Slotted only rotors are offered as an option for any of
Baer's offerings."
(
http://baer.com/cgi-bin/htmlos.exe/00839.2.3451507614300015780 )