XPost: alt.autos.toyota   
   From: crwlrjeff@yahoo.com   
      
   "Ray O"  wrote in message   
   news:h9eq5e$84l$1@news.eternal-september.org...   
   >   
   > "Jeff Strickland"  wrote in message   
   > news:h9duqo$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.   
   > --   
      
   Slots allow the gas to escape, crossdrilling increases the exposed surface   
   area so that cooling can be distributed more evenly and quicker.   
      
   Slots and crossdrilled holes are typically only made on high performance   
   brake parts, except pads. Low performance brakes don't care, and the pads   
   may or may not have a slot cut into them, depending on the whim of the   
   parts-maker. Granted, OEM parts may specify a groove cut into the pad, but   
   as a practical matter, replacement parts might or might not actually have   
   the same gorrve, and life isn't going to change if the groove is missing.   
      
   It is probably not worth the cost-up to change rotors from a standard rotor   
   to a slotted and/or crossdrilled rotor if viewed from the perspective of   
   increased performance. I made the change on my BMW solely for the looks of   
   the holes and slots, but my driving style does not require holes and slots   
   and my car does not have holes and slots available from official BMW   
   sources -- I had to get mine from an aftermarket source.   
      
   If anybody has a car that is fitted with standard rotors, making an upgrade   
   to slotted and crossdrilled rotors is not going to make much difference in   
   braking performance or reliability.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)