I finally got a pyrometer in my tool kit that I've been using to check brake temps (as well as tire temps) and figured I'd share my readings, as well as see what other people are seeing.

I do realize that the temps are going to vary vastly due to ambient temp, track, lap times, and driver... but I'd be curious to see what various brake compounds, ducts, etc do for brake temps.

How I measured was probing at three different locations within the rotor, immediately after getting out of the car.

Date measured: 9/8/13
Track: CalSpeedway
Ambient Temp: 102'

Front Brake Rotor: StopTech kit, slotted 2 piece. 328mm
Front Brake Pad: Carbotech XP12s
Front Ducting: Yes, 2" directed at rotor
Temp Measured: 150'-160'

Rear Brake Rotor: OEM, Autozone specials
Rear Brake Pad: OEM, Autozone specials
Rear Ducting: Yes, 2" directed at rotor
Temp Measured: 230'-250'


anyone else have any data? Are you seeing a 80'-100' difference between front and rears? Someone once mentioned that my autozone specials would generate more heat than a proper pad, can't say without a doubt that's true, but the initial findings point to that. I won't have proper data until I swap between the two sets at the same track.

 

I was there too.

Front StopTechs with their street pad, ducting, 160F

Rears, stock with StopTech street pad, no ducting, 360F. I was going to mock something up for the rears, but ran out of time.

Do you have a picture of your rear ducts?

 

I did this DIY (credit to Boyguan):
https://www.s2ki.com/s2000/topic/949...brake-ducting/

Interesting to see the temp differences with the rear. I wonder if my rear temps are lower because of the ducting (likely) or that I'm a pansy when it comes to braking (also likely)

 

I haven't actually measured brake temps, plus I'm an autocrosser, but front definitely gets much hotter with all OEM stuff. However when I upgraded the front to a two piece directionally vented rotor, with same ferodo pads all around, suddenly the rear is a bit hotter than front.

 

Did some closed road testing recently of my brake ducts... I wanted to know if my ducts were working and how well...

Test procedure:
1. get to 60mph
2. pass pylon
3. brake to a stop
4. mark concrete at front tire for distance
5. measure rear most of rotor for temp with pyrometer, getting hottest temp
6. turn around, do the same in the opposite direction with less than a minute between each stop.
7. Do this 2 times in each direction, then repeat... taping over one set of ducts

Front Rotors: 328mm ST Slotted
Front Pads: ST street kit
Front ducts: custom to 2" hose and flanges pointed at rotor face

Rear Rotors: OEM
Rear Pads: Autozone duralast
Rear ducts: custom, vacuum attachment to 2" hose and flanges pointed at rotor face


With ducts open:
Avg. Front Left - 203F
Avg. Front Right - 172F
Avg. Rear Left - 159F
Avg. Rear Right - 229F

Blocking left ducts:
Avg. Front Left - 234F
Avg. Front Right - 189F
Avg. Rear Left - 174F
Avg. Rear Right - 257F

Average stopping distance from 60' for all stops, of 114' (+/- 10').

I have more data, but it's pretty boring.

Looks like the front ducts work a little bit, while the rears are... nominal at best.
What this also tells me is my brakes need bleeding.

 

^good data, Obviously high speed straightaways are where you're going to get most of your brake duct benefit, which you had none of in your test. You were basically doing an autocross test. Still interesting though.

 

That's what I concluded as well... At 60mph and below, it still netted 30F decrease for the fronts and 15F for the rears.

i wish I could easily install pyrometers at each rotor to see what it looks like while moving. Might have to buy a handful of these pyrometers and go crazy

 

At Laguna Seca I was seeing rotor temps of >300 F front and >380 F rear, after the cool-down lap and 5 minutes coasting around in the pits. Rears tend to run hotter even without ducting because the rotors aren't vented and hold heat longer. At these cooled-down rotor temps I had pad fade on track with XP10/8's.

Very important to cool adequately before stopping the car at these temps. I came in without my cool-down lap on one session and the 5 minutes of coasting in the pits wasn't enough. A front rotor was cracked by the time it was my next session.

 

That's my thoughts as well... plus, less air flow to the rears, the drivetrain/wheel hubs, etc, etc. Figured, getting ANY air back there has to help a little.

 

I did somewhat similar testing to this looking at front and rear rotor temps with a thermal imager. Have look:
http://www.motoiq.com/MagazineArticl...al-Imager.aspx

The rears get super hot and don't cool down well doing to being solid rotors. From guys who've raced S2ks, it seems the rear hubs go out relatively quickly. You guys know that forum TSB about torquing down the rear axle nuts to get rid of the clicking?

Well.... my theory is the excessive heat from the rear brakes makes the rear spindles a little more ductile allowing the wheel bearings to deform the hole they're sitting in. Hence, it starts clicking as the bearing shifts a bit in the deformed hole. Then we torque down the nut more to keep it pressed in harder so it doesn't shift and click. But the heat will still make the wheel bearing fail sooner I think. Anyway, I need to work on some rear brake ducts.