Hard Brake Pedal/ No stopping

[jessew]

err, just cause the face of the pad is 700 degrees doesn't mean the fuild is going to be.... think of it like grinding a piece of metal. where it is being ground can get several hunderd degrees, but where it is being held can be comfortable to the touch (for a while). so the heat has to travel through the pad material which has a low coffecient of heat transfer. hard for heat to go through the pad, to the pad backing, to the piston, through the caliper and to the fluid. this is why race brakes on road coarse cars are huge. more pistons, more fuild, more pad area, all equal more places to disipate the heat.

brake pads do fade, take drum brakes for instance... its hard to boil the fluid in those because the wheel cylinders are so far from the pads themselves, but there is no place to help cool the pads except the drum itself since there is no air moving around in it.

I've had the brakes so hot on the mustang that pad material was imbedded into the rotors causing them to shake like a warped rotor. ( if i sprayed them with water (when cold) and let them rust up a couple of days, the rust would lift the material and the rotors would not shake anymore.) the pedal would be hard, it didn't want to stop, and the car would start shaking because the pad compound wasn't meant for that use and would create a high spot on the rotor. fixed it with better pads and rotors.

I had fade at the december autocross with the newer setup ( hawk hps, fluid, drilled/slotted rotors) like the author's problem. my rotors were so hot they turned blue... like over heated steel does.

[Ninelives17]

Feb 14, 2012 10:29:37 GMT -6 Ninelives17 said:

As I know the pads get hotter than the fluid

I heard that somewhere before I think.....

[DAN]

that was what i read about in the article about improper bedding in the pads. that it can and would often transfer pad compound to the rotor if bedded incorrectly. thus leading to much quicker fading.

you should however replace all the fluid annually its simple and effective preventive maintenance for your entire system. normal dot 4 is sufficient as you should not see anywhere near the extremes of a race car at an autox. then check all the vacuum lines at idle with a can of ether, the car will idle up when you shoot the area with the leak. for checking the booster if it has a leak that bad you should be able to hear it at idle with your head near the booster. if after this you still have the problem then buy new pads and have your rotors resurfaced. then strictly follow the manufacturers recommended bed in procedure. My two cents anyway. that is the exact way i would proceed. you should be able to replicate the failure on a straight country road with multiple hard stops from moderate speed with little or no cool down in between.

good luck with it, but in the future if your brakes fail during run five please for safety reasons don't run 6 or 7 or 8, you could kill someone as everyone expects your brakes to work and will not react to your driving as if they know your brakes don't work

[nfsp350z]

From what I have gathered here & at a couple Z forums Im going to start with checking vac lines & replacing check valve. If it persist I will look into the brake booster. Im positive its not fluid related. Levels & temps were good. Plus I NEVER experiance pedal fade. Only pedal firmness. Hopefully I will have this resolved soon. Thanks everyone for your input.

[Russ]

The check valves in our z's are inside the brake booster.

If you need another booster, I've got one non-brembo/tcs booster, and one non-brembo/vdc booster.