Track day brake issue

stb · Postby **stb** » Thu Jun 21, 2012 1:47 pm

Hi All,

Done 3 sprint days in my NA8 now, and I'm having a spongy brakes issue. Vehicle is NA8 with Hawk HP+ pads, RE001 tyres.

On the track the brakes are fine, can do 5 laps of Mallala without dramas. No fade, smoking etc, only a faint smell on returning to the pits. However, when I get back in the car for the next round, the brake pedal is extremely spongy and does not inspire confidence. However, on the track again they seem fine. Doing an extra cool-down lap of the pits doesn't seem to help.

My theory is that the rubber brake lines are going soft with heat soak in the pits, and then they cool down with some airflow on the track, and braided lines should fix it. Before I spend the money, does anyone have any alternate theories or experiences?

stb · Postby **stb** » Thu Jun 21, 2012 2:22 pm

Forgot to add that before last sprint brakes were fully flushed with new penrite synthetic brake fluid too.

Postby **NitroDann** » Thu Jun 21, 2012 2:28 pm

If you want the most ghetto way to check the brake hoses possible. Get some metal zipties, cover the entire hose both sides with them tight, and that will stop them expanding. Dont laugh its been done, costs 5 bucks and takes an hour.

Then you can spend your money.

Dann

Apu · Postby **Apu** » Thu Jun 21, 2012 3:42 pm

Well thanks Dann...right after I bought a set for the Integra :cry:

Sailor · Postby **Sailor** » Thu Jun 21, 2012 4:59 pm

Begs the question, When were the hydraulics given a full overhaul?
It can be expensive but IMHO the entire system should get a serious look at around 10 years of age even sooner if the car is being tracked.
I replaced my hoses after 6 years with SS and the feel is truly amazing.
Calipers and MC will be resealed over Xmas this year.
Brakes are bled after each meeting because they get bloody HOT! and fluid changed every year.

BTW I use SIN as well
http://www.penriteoil.com.au/pis_pdfs/0 ... 202011.pdf

Might not be age that's the problem but again IMHO better safe than sorry...and it's a good starting point.

manga_blue · Postby **manga_blue** » Thu Jun 21, 2012 5:06 pm

NitroDann wrote:If you want the most ghetto way to check the brake hoses possible. Get some metal zipties, cover the entire hose both sides with them tight, and that will stop them expanding. Dont laugh its been done, costs 5 bucks and takes an hour.

Then you can spend your money.

Dann

Try and get that through scrutineering :roll:

Sailor · Postby **Sailor** » Thu Jun 21, 2012 5:13 pm

NitroDann wrote:If you want the most ghetto way to check the brake hoses possible. Get some metal zipties, cover the entire hose both sides with them tight, and that will stop them expanding. Dont laugh its been done, costs 5 bucks and takes an hour.

Then you can spend your money.

Dann

Yeah OK.....Now all you need is to reverse the rims to get the track a bit wider and you'll be on a winner!

manga_blue · Postby **manga_blue** » Thu Jun 21, 2012 5:16 pm

stb wrote:My theory is that the rubber brake lines are going soft with old age and heat soak in the pits, and then they cool down with some airflow on the track, and braided lines should fix it. Before I spend the money, does anyone have any alternate theories or experiences?

Fixed.

x2 with Sailor on this one

Postby **NitroDann** » Thu Jun 21, 2012 5:25 pm

Laugh it up.

Its been done. Got my rally car through like that back in the day. Though with regular plastic zip ties, wasnt heat just pedal feel I was after. Ran some FTDs like that.

Dann

stb · Postby **stb** » Thu Jun 21, 2012 9:06 pm

I agree that new hoses aren't a bad thing, and I'll do that anyway, but is there anything else I should consider before I go out next time?

rossint · Postby **rossint** » Thu Jun 21, 2012 9:22 pm

How much is left on the rotors? The thinner they are the longer it will take to dissipate the heat. My brakes go soggy between runs as well, brake lines have been on the to do list for a while now.

Postby **mx5racing** » Thu Jun 21, 2012 9:31 pm

I'd still be looking at brake fluid. Just because its new does not mean it's ok for the temps reached on a track - including the massive heat soak once you have stopped.

Did the issue change at all after your recent fluid change?

We use Motul RBF600 (not 660) in all our Targa and track cars and never have issues. We also run it in the Bimmers and Porsche Boxter we just built.

I might add we did try stainless hoses on a couple of our cars but dont bother with them when building a car for someone unless they specify them.

Without a doubt the most overlooked thing on the track is brake fluid. Ive seen people spend huge dollars on rotors, pads, calipers, hoses and even master cylinders whilst still running a road based brake fluid - synthetic or otherwise......

stb · Postby **stb** » Fri Jun 22, 2012 1:38 pm

I didn't notice any improvement after changing from 'normal' fluid to the Penrite SIN fluid. SIN is rated for 310°C, Motul is rated for 311°C, so I wouldn't expect that to be the problem.

PS Hi Ross - now I recogise the car/name!