Napalm
Well-Known Member
- Joined
- June 18, 2015
- Messages
- 764
- Reaction score
- 33
- City, State
- Memphis tn
- Year, Model & Trim Level
- 2016
well ok information then.
why drilled or even slotted rotors vs today's modern ceramic pads.
the adage of drilled rotors started as a way to allow gasses built up under heat and pressure of braking with older style asbestos based brake pads - they would develop gasses as the asbestos literally burned off the pad base. since machining is expensive or it was in the 70's - it was easier to drill through the rotor face. to drilled rotors performed better under intense operation because they allowed venting.
As pads moved to more ceramic based compounds - the gassing situation went away - but with it came dusting. And more importantly glazing - glazing is where the ceramic compound started to get hot enough to re-melt (for want of a better term) and melds into a new smoother surface. some people call it glassing over since older pads when over heated literally looked like volcanic glass. Thus as CNC machineing got to be less expensive then designed to prevent this started forming up milled slots in the face of the rotor - but doing away with the drilled holes. Why - the holes were often small enough they would pack with dust and thus be worthless. The slots however allowed a contiuous hole down the face to pad interface to let the dust fall out of, while at the same time creating a edge gap that would wipe the pad surface. Thus preventing glazing.
Over time ceramic pad compounds got stronger such that they could tollerate the forces with groves in the face - note how modern pads tend to have a center groove.
This grove performs the same dust release feature - without requiring special rotors. Glazing - well with the new compounds came higher heat tollerances and better stability so modern pads don't glaze often and when they do it's not in solid sheets as before. so the glazing breaks off easier.
Thus with modern pads - drilled rotors and slotted rotors aren't nearly as advantageous. As opposed to the potential for cheap designs being out of balance, or major removal of material. Since the brake rotor is a heat sink be wary of large holes or large slots - they will take quite a bit away from the rotors ability to wick the heat away and create hot spots.
In the meantime smaller slots with a proper pattern do work rather well in extreme use - mostly track events. And they work will with special pads that often miss the middle center evac slot and are track rated for high temp. But you don't see those very often, usually specific applications like a porsche RS3.
So let's talk ultimates - Aircraft. Aircraft with steel brakes, and yes they do still exist - do not have drilled holes in them. it takes away from the heat capacity and weakens the rotor. But they can have slots in them - as will the pad rings. Same reason as above - dust evac. And even newer carbon brakes (most aircraft made after 1994) tend to also have slots. again dust evac.
So in my tracking days I used to roll with DBA (disc brakes australia) slotted only rotors and some track pads on my Holdens. Often I used Porterfield pads.
For daily driving I'd trade the track pads out for a mild street pad since track pads don't often work great when cold. My DD pad was whatever Ceramic pad I could get cheap with a quality name on it. Often Wagner Thermo-Quiets (what I roll now) or Hawk Ceramics.
I'd highly suggest the same on ANY vehicle driven on public roads. DO not use track pads on a daily driver if you can help it.
On rotors I hate CENTRIC rotors - chinese made crap - but I am very picky. And if you're paying attention that also means I hate STOPTECH rotors too. (owned by centric and also chinese made crap in a new box)
Again I'd highly recommend either plain or slotted only - if you just have to have drilled then get the smallest holes you can find.
ALso let me settle some other internet mythos right now - unless specifically made for a unique device or very thin rotors - there are no "CAST IN HOLES" in rotors - with iron alloys it would lead to porosity (holes in the substrate) which would lead to cracking and bits coming out.
notice I said specific application or very thin rotors - some motor cycle rotors do have cast in holes.
Now let's talk about the other bits of your brake system - the brake fluid and lines specifically - now I thought I read 2014 explorer - thus 2 years + old. I highly recommend while trading rotors etc - flush out your brake fluid with new. you don't need the expensive race stuff like MOTUL 600 - but for DD use I like the valvoline syn brake fluid - works great and cheap.
Flushing out the system will let the pipes and the ABS modulator live a nice long happy life - and more importantly restore your fluid boiling point - which reduces fade.
Good luck and have fun. OH one more thing - when replacing the rotors put a light coat of antiseize on the car's hub face - it will make the next removal a snap.
why drilled or even slotted rotors vs today's modern ceramic pads.
the adage of drilled rotors started as a way to allow gasses built up under heat and pressure of braking with older style asbestos based brake pads - they would develop gasses as the asbestos literally burned off the pad base. since machining is expensive or it was in the 70's - it was easier to drill through the rotor face. to drilled rotors performed better under intense operation because they allowed venting.
As pads moved to more ceramic based compounds - the gassing situation went away - but with it came dusting. And more importantly glazing - glazing is where the ceramic compound started to get hot enough to re-melt (for want of a better term) and melds into a new smoother surface. some people call it glassing over since older pads when over heated literally looked like volcanic glass. Thus as CNC machineing got to be less expensive then designed to prevent this started forming up milled slots in the face of the rotor - but doing away with the drilled holes. Why - the holes were often small enough they would pack with dust and thus be worthless. The slots however allowed a contiuous hole down the face to pad interface to let the dust fall out of, while at the same time creating a edge gap that would wipe the pad surface. Thus preventing glazing.
Over time ceramic pad compounds got stronger such that they could tollerate the forces with groves in the face - note how modern pads tend to have a center groove.
This grove performs the same dust release feature - without requiring special rotors. Glazing - well with the new compounds came higher heat tollerances and better stability so modern pads don't glaze often and when they do it's not in solid sheets as before. so the glazing breaks off easier.
Thus with modern pads - drilled rotors and slotted rotors aren't nearly as advantageous. As opposed to the potential for cheap designs being out of balance, or major removal of material. Since the brake rotor is a heat sink be wary of large holes or large slots - they will take quite a bit away from the rotors ability to wick the heat away and create hot spots.
In the meantime smaller slots with a proper pattern do work rather well in extreme use - mostly track events. And they work will with special pads that often miss the middle center evac slot and are track rated for high temp. But you don't see those very often, usually specific applications like a porsche RS3.
So let's talk ultimates - Aircraft. Aircraft with steel brakes, and yes they do still exist - do not have drilled holes in them. it takes away from the heat capacity and weakens the rotor. But they can have slots in them - as will the pad rings. Same reason as above - dust evac. And even newer carbon brakes (most aircraft made after 1994) tend to also have slots. again dust evac.
So in my tracking days I used to roll with DBA (disc brakes australia) slotted only rotors and some track pads on my Holdens. Often I used Porterfield pads.
For daily driving I'd trade the track pads out for a mild street pad since track pads don't often work great when cold. My DD pad was whatever Ceramic pad I could get cheap with a quality name on it. Often Wagner Thermo-Quiets (what I roll now) or Hawk Ceramics.
I'd highly suggest the same on ANY vehicle driven on public roads. DO not use track pads on a daily driver if you can help it.
On rotors I hate CENTRIC rotors - chinese made crap - but I am very picky. And if you're paying attention that also means I hate STOPTECH rotors too. (owned by centric and also chinese made crap in a new box)
Again I'd highly recommend either plain or slotted only - if you just have to have drilled then get the smallest holes you can find.
ALso let me settle some other internet mythos right now - unless specifically made for a unique device or very thin rotors - there are no "CAST IN HOLES" in rotors - with iron alloys it would lead to porosity (holes in the substrate) which would lead to cracking and bits coming out.
notice I said specific application or very thin rotors - some motor cycle rotors do have cast in holes.
Now let's talk about the other bits of your brake system - the brake fluid and lines specifically - now I thought I read 2014 explorer - thus 2 years + old. I highly recommend while trading rotors etc - flush out your brake fluid with new. you don't need the expensive race stuff like MOTUL 600 - but for DD use I like the valvoline syn brake fluid - works great and cheap.
Flushing out the system will let the pipes and the ABS modulator live a nice long happy life - and more importantly restore your fluid boiling point - which reduces fade.
Good luck and have fun. OH one more thing - when replacing the rotors put a light coat of antiseize on the car's hub face - it will make the next removal a snap.
