Results 1 to 6 of 6

Thread: rotor temperature, vs pad temperature

  1. #1
    Join Date
    Aug 2012
    Location
    Central, MD
    Posts
    3,845
    My Cars
    1995 M3

    rotor temperature, vs pad temperature

    Pad manufacturers show mu vs temperature charts.
    I assume that's the temperature of the rotor?

  2. #2
    Join Date
    Mar 2017
    Location
    Oahu / Los Angeles
    Posts
    1,011
    My Cars
    S54 E36
    Hey there

    That's how I've matched up my pads and rotors by using Genesis temperature paint on the end of the rotor at the vanes.

    You get the max rotor temp with the paint and then get a pad that has a range where that rotor temp lands somewhere within that range.

  3. #3
    Def's Avatar
    Def is offline Lead Disagreement Eng PE
    Join Date
    Aug 2002
    Location
    Seattle, WA
    Posts
    13,547
    My Cars
    SW22, Volt
    Rotors are being actively cooled and have much more mass than the pad. So your pad temp will definitely be a decent bit higher than the rotor temp, which is based on... variables.

    Ever notice how a pad compound that's borderline on fade works great when the pad is near new and has a lot of mass to damp out the temperature spikes in braking zones, but as it wears down it's much more likely to fade? This is due to there being much less pad mass to absorb those spikes of heat input, so your max pad temperature is going up as they wear down. So you can see that even on the same sets of components, as everything wears, the amount the pad will be hotter will vary over time.

    My best guess based on a few temperature measurements and seeing pads fade is that the peak pad temp ranges from 200-400 deg F over rotor temp.

  4. #4
    Join Date
    Aug 2012
    Location
    Central, MD
    Posts
    3,845
    My Cars
    1995 M3
    I know the thermal variations of the pad and rotor are quite dynamic. But isn't the pad material much less conductive of heat than the rotor?
    So I'd think the pad material will stay lower than (not above) the average rotor temperature, where as the rotor temp will rise/fall quickly in hard braking zones.

    As pads get thinner, yes, they have less thermal mass, so, I could see the average pad temperature running closer to the average rotor temperature as they get worn.

    - - - Updated - - -

    And of course, depending on light, it either looks beige or yellow-green. UG.
    I'm hard pressed to believe I'm getting to 800C temps, even on a 100deg day.

    Attachment 675230

    2.jpg

  5. #5
    Join Date
    Mar 2017
    Location
    Oahu / Los Angeles
    Posts
    1,011
    My Cars
    S54 E36
    I already had all this shit on m3forum.net so I don't want to post it all again, but I'm on HAWK DTC-60 pads up front and they're perfect with these 993TT Brembos fronts and DTC-30 pads in the rear on 996 Brembos.





    Fronts:


    Rears:

  6. #6
    Def's Avatar
    Def is offline Lead Disagreement Eng PE
    Join Date
    Aug 2002
    Location
    Seattle, WA
    Posts
    13,547
    My Cars
    SW22, Volt
    Quote Originally Posted by aeronaut View Post
    I know the thermal variations of the pad and rotor are quite dynamic. But isn't the pad material much less conductive of heat than the rotor?
    So I'd think the pad material will stay lower than (not above) the average rotor temperature, where as the rotor temp will rise/fall quickly in hard braking zones.

    As pads get thinner, yes, they have less thermal mass, so, I could see the average pad temperature running closer to the average rotor temperature as they get worn.

    - - - Updated - - -

    And of course, depending on light, it either looks beige or yellow-green. UG.
    I'm hard pressed to believe I'm getting to 800C temps, even on a 100deg day.

    Attachment 675230

    2.jpg
    Kinetic energy is converted to heat energy at both the rotor face (which is continually moved away from this heat flux interface), and the pad face which just stays there and heats up. The rotor is more conductive, but all that means is it'll move the heat via conduction across its whole thickness easier than brake pads. Hence your pad interface temps definitely being hotter than the rotor temps.

    I've definitely nuked/badly faded 1200-1300 F MOT pads with rotor temps that were about 750-800 F after a really quick half lap cool down (so probably seeing 900-950 F in braking zones).

Similar Threads

  1. Using Engine Core Temperature vs. Water Temp Cluster Gauge
    By pepkat in forum 1996 - 2003 (E39)
    Replies: 10
    Last Post: 04-28-2014, 01:25 AM
  2. rotor slot patterns vs pad compound
    By APEXraceparts in forum Track, Auto-X & Drag Racing sponsored by Bimmerparts.com
    Replies: 0
    Last Post: 08-04-2009, 10:06 AM
  3. brake rotor vs. pad life / replacement intervals
    By paintpro21 in forum Track, Auto-X & Drag Racing sponsored by Bimmerparts.com
    Replies: 9
    Last Post: 01-07-2008, 02:39 PM
  4. Installing new rotors and brake pads...
    By QuestMCoupe in forum 1991 - 1999 (E36)
    Replies: 9
    Last Post: 03-18-2003, 01:11 AM
  5. The never-ending brake, rotors and track pads thread
    By Mike Mount in forum 1992 - 1999 M3 (E36)
    Replies: 5
    Last Post: 03-21-2001, 05:24 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •