defining brake wear

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Feb 25, 2006 | 07:23 AM
  #1  
Does anyone know what does [6mm left out of 11mm] equate to in % of wear for stock front brakes? I'm getting conflicting info from 2 diff dealers: one says I've got at least 50% left, while the other says i've got 15%.

which to believe?

since I've bought my used car 2003.5 here in Quebec Canada, the first dealer (who sold me the car) is obliged by law to change my breaks if they're more than 50% used on their dime (the 36k/3year warranty is over).. I just have the fealing the first dealer is trying to screw me over.

thx
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Feb 25, 2006 | 09:18 AM
  #2  
Wow.....

If they say you have 6mm of pad left on an 11mm new spec.....that is simple math to get the percentage.


You have 54.5% of your pad remaining.
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Feb 25, 2006 | 01:35 PM
  #3  
2mm is considered the unsafe point, however the thinner the insulative effect of the pad material the hotter the brake fluid gets [via conduction thru material, thru backing plate to piston].

The safety factor has to do with the caliper piston seals which gets stretched when pads are thin and rotors are thin..........so worn pads on new rotors are safer than worn pads on worn out rotors from the perspective of the possibility of seal failure and loss of brake pressure.

I always try to change pads BEFORE the 2mm point so 6 out of 2 means 4mm left you have used 5mm out of 9mm [usable] = 55% or 45% left to use.
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Feb 25, 2006 | 04:25 PM
  #4  
Quote: 2mm is considered the unsafe point, however the thinner the insulative effect of the pad material the hotter the brake fluid gets [via conduction thru material, thru backing plate to piston].

The safety factor has to do with the caliper piston seals which gets stretched when pads are thin and rotors are thin..........so worn pads on new rotors are safer than worn pads on worn out rotors from the perspective of the possibility of seal failure and loss of brake pressure.

I always try to change pads BEFORE the 2mm point so 6 out of 2 means 4mm left you have used 5mm out of 9mm [usable] = 55% or 45% left to use.
Q45tech, is 2mm measured from the sensor or the metal plate? the mesurements I gave are from the metal plate and not the sensor (you know the thing that make your braking squeal when worn out) and doesn't that sensor damage my rotors if I'm running on them?
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Feb 25, 2006 | 05:52 PM
  #5  
Sensor squeels in reverse. The metal plate does not enter into the equation.........make sure you have 2mm [0.07874"] of actual pad compound when you replace.

Heck as cheap as oem pads are compared to a wreck [plus insurance increase] or hospital stay change them half worn...........same with tires.
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Feb 27, 2006 | 03:43 AM
  #6  
wow, no comment. simple math.
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Mar 3, 2006 | 03:47 PM
  #7  
ok I know this is simple math. But here's how they calculate it officially at the dealer:

(6-2mm)/(11-2mm) = 44% left for the fronts
(6-2mm)/(9-2mm) = 57% left for the rears

just an FYI

oh wait... q45tech did mention that....
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