Why do brakes go soft when used on a trackday? Is it caused by the type of brake pads, the discs not good enough, the brake fluid or what?

 

Running on a set of standard Nissan brake pads, Tarox 40 groove discs, braided brake hoses and DOT 5.1 brake fluid replaced 5/6 months ago. As the front discs are warped I was leaving them on for the trackday so as not to screw up the new ones I have ready to be fitted, but I didn't expect the pedal to go soft after 4/5 laps. So is it the pads? Should I have put on the EBC green stuff pads that are in the garage? I know the best solution is to go for a big brake kit but surely they should be able to last longer than this or is that naive?

 

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Z first and anything else is secondary!

John Newcomb (NukeEm)

www.geocities.com/jn300zxtt

Hi John - in advance of the real brake gurus, the answer to your question is "yes". It's all of these (don't ask me in which order, tho').

 

You also need to factor in heat build-up. A particular brake set-up (i.e. combination of pads / discs) works best within a (relatively) narrow range of temperatures. For example, a full-on carbon fibre brake setup doesn't work until it's at 600°C or so - which explains why race disks glow in the dark.

 

I would guess, therefore that your brakes got too hot after about 4/5 laps and their performance dropped.

 

I doubt whether Nissan OEM pads are built for track day use (temperatures). Aftermarket pads are available for fast road, track, race. So if you get a good setup for the track, they could well be lousy for the road because they never get hot enough.

 

Did they come back when cooled down - i.e. later that day or the next day?

 

I believe heat build-up also affects the behaviour of the fluid - i.e. softer. And, I guess it would also affect the brake hoses - heating them up allowing them to distort more which is why us bikey types tend to throw away OEM pipes and fit aero-spec braided Goodrich (if that's how it's spelt).

 

Now - over to the gurus......

 

[This message has been edited by Gio (edited 23-08-2002).]

Sorry if I'm repeating anything here - can't be bothered reading LOL

 

It sounds like maybe you have air in your brake fluid John. Best bet would be to do a complete flush of the system and renew with DOT 5.1 fluid.

 

Get the R33/34 brake upgrade too - I cannot stress what a difference this makes to the driveability of the car...

 

HTH

 

CheerZ,

 

Andy

If the brakes go soft, isnt that classed as faiding?

Standard pads are not made for constent hard use.

 

Stuart

Thanks for the info guys, I had hoped that they would be ok for one last blast on track before I threw them away but obviously not. For a seperate reason the car has to go back in to the garage again so I will get the discs replaced with the new ones I have already stored away in the garage, a pair of Brembo Cryo discs, EBC green stuff pads and get the brake fluid replaced again. I can't afford the big brake change this year, maybe next year.

EBC now reccomends Red Stuff for Z's instead of Green Stuff. I recently got new pads and got the Green Stuff because I mainly drive in London but I believe the Z is over the weight limit for using Green Stuff on the track.

 

Red Stuff V2 is supposed to warm up faster than V1 and be much more suited to road use.

Even if the fluid is 5.1 doesnt mean its super good though, its just about comp[atibility standards - once again i will reccomend castrol srf fluid, its eexpensive, but the best for track use. People I know have gone from fading brakes all the time, till after they change and the exact same brake setup (excpet for the fluid) no fading. Its really good stuff! give it a go if you are chaning fluid anyways.

I used Red Stuff pads a while ago and they took about a month to bed in and wore out the following month!

2 months use from £90 squids worth of pads

I have grooved and cross drilled disks and I do give it serious welly all the time but my pads have always lasted at least 6 months before even on standard ones.

They are crap when cold too but they really do stop you once you've warmed em up.

I live on a hill and first thing in a morning I used to nearly run out into the main road at the bottom! :S

They were meant to be dust free but that only lasted a month and my wheels turned blacker than you've ever seen!

Maybe the new V2 formula is better...