MDL-01C5

Tonight at the track, at the end of a run when I hit the brakes, they barely worked...the pedal wouldn't press down more than about an inch or two-- and were very poor in stopping the car, no matter how hard I pushed it was super-stiff...it really freaked me out <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />
There's 20K miles on the car, and I've been to the track many times before this-- it's never happened before--the only difference was that I was using 17" wheels for my Nitto's instead of the stock 18" wheels... but I see no correlation between that and my failure.
Why did this happen?

<small>[ May 10, 2002, 11:59 AM: Message edited by: MDL-01C5 ]</small>

roy

Possible frozen caliper

BIGBOS

I had a similar problem to this on every run...I was running my et streets though, as soon as I get through the traps I would get on the brakes and it felt like nothing was there....and the low trac light kept coming on and off over and over again...eventually as soon as I got under 50 it started to stop..

Can anyone explain this crap?

MDL-01C5

ttt

BIGBOS

TTT

mitchntx

iTrader: (14)

Check your brake pads.

They may've glazed. Has it done it since then?

zombiedude

iTrader: (1)

I'm just throwing this out there. Does the tire diamiter on the front and back have to be the same for ABS since the tires from factory were? If the tires were smaller in front, would the ABS think the rear were locking up (since they would be going slower) and Activating the rear for them to catch back up with the front tire speed? Just a thought.

MDL-01C5

ABS uses a regulated pulse of the brakes to slow the car without losing traction--
having a different tire size would affect Active Handling, but shouldn't have any impact on ABS--
Also, It has not happened since-- I return to the track tomorrow--

BIGBOS

I felt my rotors after the run(s) where that happened, they were really hot, but didn't feel warped...

SILVER BULLET

iTrader: (1)

On my SS I have a 28" diameter in the rear and a 25" front and people have been having problems w/ ABS because of the different size tires Sometimes if you pump the pedal it will get better and go away

Sky042

iTrader: (1)

there have been people reporting issues when running different sized rims on front and back that does cause the ABS system to freak out because the wheels are not rotating at the same rates.

msce2b-dustin

Same problem here. I also get the no abs light and brake in op light or soemthing like that on the way to the track when I hav e the et's on.

At the end of the run i also usually get the low traction light as well.

red ws6 99

Since no one really answered this is what I think. You guys are not using a line lock that I could see. So your back brakes are fully applied during a burnout. That gets the rotors very hot, which in turn boils the brake fluid. Brake fluid boils you get no brakes. This probably does not happen unless you are running et streets or something like that. Street tires dont have the grip to cause this problem.

Gary

MDL-01C5

red---- now THAT's the kind of answer I've been looking for-- many thanks to the other helpful replies, but at least in my situation (which, by the way, has not re-ocurred) I know ABS has nothing to do with it, the feeling is an altogether different one than the ABS, which I've experienced the feel of many times...I also have my Traction control and Active Handling turned off when I race-- and the wheels on the car were the same size for me-- both 17's.. though Rear stock is 18", I'm pretty certain that had no bearing on the cause-- especially all the time spent to and from the track with them on (~50 miles one-way)
The brake fluid option makes a lot of sense, and I'm thinking that I had just made run prior to that one...so in addition to the heavy braking at the end of the first run, I turned around and played John Force minutes later....which may well have super-heated the fluid...resulting in the "hydro-locked" feel of the pedal...
Thanks for the opinions and ideas, all-- <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" /> <img border="0" alt="[Burnout]" title="" src="graemlins/burnout.gif" />

<small>[ May 27, 2002, 04:12 AM: Message edited by: MDL-01C5 ]</small>

mitchntx

iTrader: (14)

You don't boil the brake fluid, you boil the water the fluid has absorbed over the months/years. This boiling creates steam and therefore traps air bubbles in the caliper.

This will result in a long pedal, not a short, hard pedal. As you mash the pedal down, the air bubbles compress under the hydraulic pressure of the fluid. Air compresses far easier than fluid. Hydor-locking occur when you are attempting to pump fluid, like fuel, rather than compress fluid, like in the braking system.

As you described in your first post, the pedal was hard and you mashed the pedal hard but it was like nothing was happening to slow you down.

This phenomenon has nothing to do with ABS (pulsing pedal) or fluid (long pedal) rather pad performance (friction against the rotor).

I suggest you glazed your pads. It happens when they are super heated, then not used while cooling. A hardened glaze of brake dust sticks to the surface of the pad, which has very little friction coefficient. Same principle plays into heating and cleaning your tires just before a pass.

In road racing, after a session, we bring the brake temps down gradually to prevent glazing and rotor warping.

If the pads are glazed, a good hard braking session will remove the glaze and the brakes should perform as normal. You will probably see an abnormal amount of brake dust just after the glaze "clean-up".

There is nothing harder on brakes than sitting in staging, easing up to the line, doing a 110mph blast, nailing the cold brakes and then easing back to staging to sit for an hour. That temperature shock will glaze pads and warp rotrs faster than anything.

FWIW ... MHO

<small>[ May 27, 2002, 11:11 AM: Message edited by: mitchntx ]</small>

MDL-01C5

Another valid point-- Thank you for your insight <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

red ws6 99

Guess I should have read your question all the way through, did not notice that you had a hard pedel and not a soft one. At least mitchntx was paying attention.