Brake temp after cool down lap at rotor and caliper

BGTV8

As a comparison, my Z34 sees ~250C rotor temps after a cool-down lap following a half-hour session at Philip Island GP circuit (which is quite high speed, but only has 2 "big" stops and a couple of more moderate stops). A "big" stop is one which requires coming back 3 or 4 gears and a moderate stop is 1 or max 2 gears - anything else I call a "lift-and-dab". This is in a 105-108 second lap and cool downs are maybe 2m30s from the chequered flag to being back into the paddock and ready to park.

It is a stocker (no weight reduction) but with special-order DBA rotors (DBA2750 special metallurgy and heat treatment for Robinson Racing who run Falcon GT's in the Australian Production Car Championships - I got a couple of sets for my Z34 as a favour from one of their sponsors and made hats to suit), Akebono calipers and the Stillen "baby" 2" ducts fed from the fangs in the bumper. I use Endless MX72, Ferodo DS2500 and/or PMU HC+ pads depending upon what is available when I need pads. Tyres are currently Yoki A048R.

600-degF is perhaps a little high, but that is without knowing exactly what circuit you are referring to, the nature of its braking demands and the duration of the cool-down lap. IMHO, the most significant factor will be to ensure that the rotor can cool evenly which implies rolling the car forward (or back) about a quarter rotation of the wheel every 90 seconds such that the pad is not sitting on the same spot on the rotor for more than 90-seconds at a time. This will stop the pad "heat-treating" just one part of the rotor friction surface which can be a cause of brake pedal pulsation as the pad bites differently on the segments of the rotor that have seen differential cooling. I'd not stop rolling the car until rotor temps are under 150 degC

FWIW

RB

Mike

me too

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NISSAN: 75 280Z / 86 300ZX GLL /87 Sentra SE / 03 350Z / 23 Z
Porsche: 93 968 / 23 Macan GTS / 93 968

Mike

It was great before I had the CJM fuel system fix. I would come off the track and drive 5-10 minutes to the gas station every session to top up, that really cooled everything down nicely. Now I don't have that option anymore since the fuel is fixed and the car isn't street legal.

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NISSAN: 75 280Z / 86 300ZX GLL /87 Sentra SE / 03 350Z / 23 Z
Porsche: 93 968 / 23 Macan GTS / 93 968

ValidusVentus

Anything new regarding this?

I know my front brakes get awfully hot even with the small Stillen ducting. Even the XP10s on the front were getting pretty thick visible deposit buildup on the rotor surface last weekend. After a while I could definitely feel the rough surface of the rotor in the brake pedal in a few brake zones. Didn't warp or significantly crack the rotors though. I did drive around the paddock for a few minutes after the cooldown lap and pushed my car back and forth a bit after I parked it. Thinking of hacksawing a shallow tangential groove (and filing the edges) into the middle of the XP10s since they dont have one (even though I do use slotted rotors) and they do have those 2 small holes which are maybe intended to perform the same function?

Actually, come to think of it I did quickly borrow an IR and hit my right front rotor last weekend. I think it was right up close to 600, obviously after the cooldown lap and parking it.

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Mods: Dedicated caged track car, lots of things. ||| Valkyrie Autosport |||

sig11

Unless I'm misunderstanding you I think that is a REALLY bad idea. :P Seems like it would give you a really good chance of the pad material disintegrating.

What would you hope to gain from that?

ValidusVentus

Which is why I haven't done it and mentioned it here . It used to be common practice with some race teams (cutting them), (don't know if its still done, I had assumed all race application pads now had them from the factory) in fact Carrol Smith talks about it in his book Tune to Win. The goal is to give the (new and old) brake dust somewhere to go rather than being pushed back into the rotor material by the rest of the pad. This way more of the pad is seeing a clean/clear surface when it makes contact with the rotor. It also helps somewhat with cooling the pad. It doesn't have anything to do with gassing, which is a thing of the past.

Also I don't believe there is anything special about the material at the front or back edge of the pads to begin with so how would adding another front and rear edge do anything bad?

I started a new thread on this so I wouldn't be jacking your thread OP as this was getting a little long:

Groove

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Mods: Dedicated caged track car, lots of things. ||| Valkyrie Autosport |||