Well after an absolutely brilliant day at Calder yesterday I have totally eliminated (worn out) my set of brake pads and am now hunting down replacements. Repeatedly hauling down from 207kmh (130mph) to around 1/3 of that speed in approx 100 metres kinda does that to the brakes.

I have a question though. My brakes now feel totally spongy even when cold. I can now easily push the pedal to the floor and hear the click as the pedal bottoms out. I'd like to understand the reason for this. I can think of a few possible causes.

1. The pads are now worn causing the pistons to be sticking farther out of the cylinders - the increased amount of brake fluid behind the piston is able to be compressed easily giving a spongy feel.

2. The brake fluid itself having been heated up considerably has either absorbed air (water) or has somehow lost its quality of incompressibility.

3. The piston/cylinder rubber seals are now stuffed due to heat damage.

Can anyone confirm what the nature of the problem is. Will replacing fluid and pads solve my problem or is something further required.

Any recommendations for fluid/pads?

 

Do these things:

Get some DOT4 brake fluid.

Buy some speedbleeders.

Install speedbleeders.

Flush brake system with new DOT4 fluid

Buy brake pads for H and A Accessories.

Replace pads.

Sign up for next track event.

 

Lot's of high-speed stops causes heat generation. Heat transfers through pads/brake piston to fluid. Fluid boils, and air bubles are created in the brake lines. Air is compressable, fluid is not, hence the spongy brake feel.

This is why track cars use high (boiling point) temperature fluid, and bleed their brakes often.

In addition, the stock honda pads have been known to not hold up well under track conditions. They undergo some type of chemical transition, and cause scoring to your rotors as well as crumbling.

[QUOTE]
[B]

 

pfb has it exactly right.. you need to replace the fluid and it can be done without the speedbleeders, but they make it so much easier. There are a number of pad choices but the R4S work pretty well and are relatively inexpensive.

 

If a track event isn more than a few months off, I bet you can restore much of the braking feel by bleeding the brakes.

I concur with the suggestions of meat, pfb and cdelena as prudent preparation for the next event. I'm currently using the Speedbleeders, Porterfield R4S pads and Valvoline SynPower brake fluid. This setup is much better than the orignal pads and fluid.

The other upgrades that were suggested will be of benefit, but with less "bang for the buck" (IMHO). Also, they will take you out of stock autocross class if that is relevent to you.

Betcha can't wait until your next track outing!

 

CoralDoc-

to clarify- will the speedbleeders, R4S pads and better fluid take us out of stock class? Or is it the braided lines and air duct? Or any one of these? thanks!

-vic

 

It is my understanding that brake ducts and stainless steel brake lines are not permitted for SCCA SoloII stock classes (if not originally fitted). The brake pads, fluid changes and speed bleeders are allowed. In fact, our local autocross guru, Jason Saini, drives a car with most (all?) the allowable upgrades including different shocks, cat-back exhaust, thermostat, front swaybar, brake pads, air filter and DOT legal "race rubber". Check out the racing and competition forum for some great ideas on car preparation and setup.

 

Thanks guys, I much appreciate your feedback.

My track days are not real serious competitive events (oh yeah, as if anyone can hold back their competitive spirit once on the track ) so I am not concerned about breaking any class rules. I also won't be back on the track again for a couple of months so I think I will take CoralDoc's advice and try bleeding the brakes (along with new pads of course).

PFB, the fluid boiling is what I figured was the case - it's amazing how hot those front rotors were getting (see TWOK's post regarding track marshals commenting on the red hot glow of rotors during braking at the end of Calder straight). I also have scoring on my rotors, it's not too bad but I think justifies a quick skim of the rotors.

Are the R4S pads going to be OK for the street (i.e. not too hard a compound) or should I use stock pads on the road and swap the pads to R4S whenever I get on the track?

 

[QUOTE]Originally posted by 2kturkey
[B]Are the R4S pads going to be OK for the street (i.e. not too hard a compound) or should I use stock pads on the road and swap the pads to R4S whenever I get on the track?

 

Boiled fluid.....other posters are dead on. You need to replace the fluid and upgrade to a DOT 4 if you are going to the track again......