All too often brake fluid considerations fall by the wayside.  Not just for daily driving but especially for track days when brake fluid comes into its own as far as braking performance is concerned.

Brake fluid is hygroscopic meaning that its good at absorbing moisture. This is apparently a manufacturers design parameter for brake fluid because it means that any moisture in the brake system won't amass and cause corrosion in the pipes or even freeze in cold temperatures which could result in the brakes failing or split brake pipes due to the expansion of the frozen water.  So instead moisture is absorbed thus avoid these problems.
This solves one problem, but creates another. Brakes operate at high temperatures. This is especially the case on track with hard braking repeated from one corner to the next and unlike daily driving doesn’t provide much time for the brakes to cool.

While most of the heat is transferred away from the braking components by cooling ducts and vented discs, a lot of this heat is still transferred to the brake calliper and pads and in turn heating the brake fluid. Brake fluid therefore has a high boiling point, typically typically more than 200 degrees Celsius, but water has a boiling point of only 100 degrees Celsius. Small amounts of water absorbed into the brake fluid reduces the effective boiling point down to temperatures way below this level and typically to circa 140 degrees Celsius depending on levels of braking and atmospheric conditions.
So, if the fluid boils, you can get pockets of water steam in the brake system which is more or less the same as having air in the brake lines. Unlike brake fluid these steam pockets are compressible,  so when you stamp on the brake peddle as you approach a sharp bend, you end up using valuable braking energy to compress the steam pockets rather than clamping the brake pads against the brake discs.  The end result is that you will feel the brakes progressively losing their effectiveness and they wont feel positive under foot.  Ultimately they will fail and maybe cause an accident.

So for these reasons, it is absolutely vital to change and/or flush your brake system regularly.  You also need to chose a brake fluid with boiling point specifications to withstand the heat of track day driving.

Buy Castrol SRF - end of Can we go down the pub now ?

Quote: GaryH at Oct 20, 2008 8:18:59 pm

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Buy Castrol SRF - end of Can we go down the pub now ?

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I totally agree mate.  Mine's SRF all the way.  Yes we can go to the pub, but I spent all my money on SRF

SRF is not that expensive versus other race fluids out there
And remember that with SRF you need to bleed the brakes about a third as often which saves on labour costs if you're paying someone, and effort if you're doing it yourself!!

Or Carlo loads of effort (if you're not doing it yourself)

I have to say I'm a bit of a fan of AP600, but have also used SRF.
Bled thru a P968 at Spa recently (yes, the weekend I was on hols, but still ended up doin some spannering...) improved things no end. The driver was braking as late in the wet, after bleeding, as he was the previous day on the old fluid, in the dry. Dont know what the old fluid was or how old it was, tut! Anyway, he finshed 5th o/all.

So, I've done some research, AP600 has same declared dry boiling point as SRF. As Carlo says, correctly, you dont need to change SRF as often as its wet boiling point is a good 35deg higher than AP. But; if you bleed a race car before and during meetings, then AP is a tenner cheaper.

Gwyn

Nice work Gwyn - I have just changed out my fluid for SRF. I have completely overhauled my complete braking system for a turbo master cylinder and brembo GTPL's.  I have yet to use it on the track but am looking forward to putting SRF through its paces.  If AP600 has the same properties of SRF but is cheaper then it must be a serious contender. Cheers fella.

i weighed up the pros n cos of srf and super blue  good coments for both but as i'll prob only track it 2 times a year i
went for ds3000's and super blue oh and the missis did the paint work on the calipers  she is for hire at a decent rate!!!

Motul 600, used it for years, never had a problem with brake fade.

Quote: hukent at Jan 09, 2010 1:02:42 pm

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Motul 600, used it for years, never had a problem with brake fade.

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Motul definitely has a good reputation for sure.

ive just bought super blue. Hope its up to the job. Am putting in new OEM pads, discs, braided brake lines and the fluid in this weekend.
Other than the turbo thomas exhaust i havent got any other go-faster mods and the car has lost some moderate weight, so based on that, will i need better pads and fluid for a track day at Spa in June ?  I dont want to go all that way for a lifetime ambition and get sidelined by boiling fluid and brake fade !!
I would have bought ds2500's for this brake refurb if i hadnt already bought all the OEM stuff. My thought is to run with this setup, bed in the pads etc then maybe swap out the pads for ds' nearer the time. Be a real pain to swap fluid again in such a short time.

Spa has long old straights so hopefully brakes get a good chance to cool between some corners.

Going 'On Track' with a standard road car is always a compromise.
As long as you start off steadilly for 3 or 4 laps, not attack the circuit, late braking and chucking the car about,
you won't have a problem with the standard set up.
I have never boiled my brakes in a road car or competition car, because i drive them accordingly.
Warm everything up PROPERLY, brake normally BEFORE the corner and drive the car through the bends.
Your tyres will take more punishment than the brakes, especially at Spa, which is a high speed circuit with
mostly gentle corners and bends.
But don't worry, we'll look after you.

Quote: hukent at Feb 18, 2010 6:21:02 pm

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Going 'On Track' with a standard road car is always a compromise.
As long as you start off steadilly for 3 or 4 laps, not attack the circuit, late braking and chucking the car about,
you won't have a problem with the standard set up.
I have never boiled my brakes in a road car or competition car, because i drive them accordingly.
Warm everything up PROPERLY, brake normally BEFORE the corner and drive the car through the bends.
Your tyres will take more punishment than the brakes, especially at Spa, which is a high speed circuit with
mostly gentle corners and bends.
But don't worry, we'll look after you.

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I totally agree.  If you drive properly and take your timen getting things up to temperature comonets should last  little longer.  I have suffered with brake fade after prolonged use, but a quick trip to the pit and a cup of coffee fixed the problem 

Dont worry i am no newbie to a track !  It was more a concern of whether the stock pads and super blue would be up to it on these older cars. I used stock on my far heavier 964 without problem so would hope the more nimble 3.2 should be okay too.
Glad to hear your going too Hu. How about you Pete?...you know you want to

I don't see a problem as you are not a complete novice, you must remember Porsche cars are 'race bred' so are better
equipped than most for track days.
Also don't believe ALL you read on I.B. some of them spout a lot of ''*ullshit''!!!

Quote: hukent at Feb 19, 2010 8:27:13 pm

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I don't see a problem as you are not a complete novice, you must remember Porsche cars are 'race bred' so are better
equipped than most for track days.
Also don't believe ALL you read on I.B. some of them spout a lot of ''*ullshit''!!!

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That is something I love about the Porsche,especially the older one like ours.  Porsche designed their cars to be driven to the track, thrashed around the circuit and then driven home again.  I love e'm fo that!

Quote: Pete at Feb 20, 2010 9:04:41 am

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[quote=hukent;29;1266611233]I don't see a problem as you are not a complete novice,
That is something I love about the Porsche,especially the older one like ours.  Porsche designed their cars to be driven to the track, thrashed around the circuit and then driven home again.  I love e'm fo that!

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Amen to that !

Cant wait to go, Spa is on my lifes 'to do' list, always has been 

Hu, can your mate at Lloyd rallying get a decent deal on DS2500's? I might get a set before Spa, funds allowing, though not sure yet. Will see how the brand new pads, discs and fluid feel after this weekend. My brakes are like sponge-man bob at the moment!

Quote: MarkJ at Feb 20, 2010 12:00:18 pm

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Quote: Pete at Feb 20, 2010 9:04:41 am

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[quote=hukent;29;1266611233]I don't see a problem as you are not a complete novice,
That is something I love about the Porsche,especially the older one like ours.  Porsche designed their cars to be driven to the track, thrashed around the circuit and then driven home again.  I love e'm fo that!

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Amen to that !

Cant wait to go, Spa is on my lifes 'to do' list, always has been 

Hu, can your mate at Lloyd rallying get a decent deal on DS2500's? I might get a set before Spa, funds allowing, though not sure yet. Will see how the brand new pads, discs and fluid feel after this weekend. My brakes are like sponge-man bob at the moment!

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Very likely he can, E-mail him with what you want.
Your brakes should be as solid as a rock if you have renewed everything,
I would say you need to re-bleed them.
Modern brakes require NO bedding in.

Thanks Hu, may well do that. Should i drop your name into the equation?

By the way the spongey brakes is whats there at the moment despite a 12k service from a reputed p-specialist  , all the new stuff goes on tomorrow
Got a manic day ahead, all new brakes all round: discs, pads, braided hoses. Then ive got a WEVO shifter to install and replace the gearbox oil with Swepco....simples.

Mention my name if you wish,
getting the Swepco into the 'box is the toughest job,
warm it up first.