Hey guys, I've been road racing/autox lately (our autox courses are mini road race courses we use a sheriffs training course and reach speeds of up to 60-80 a few times) but anywho, i'll come into a corner braking. The car feels like it can stop harder so i'll gradually put more pedal down and my front wheels will lock up. usually just 1 wheel.

I've had a licensed road racing friend drive my car and he's told me something's not right and we can't figure it out

My car is a 99 ex civic
I have a 1" 99 integra Master Cylinder, 40/40 prop valve
HPS' all around
Steel braided lines in the front, stockers in the rear
This will also happen when the front tires are at a real good grippy temp, (i'm on 215/45/16 so i have plenty of tire and shouldn't be locking these up in the first place with the amount of pedal i'm pressing.

My road racing friend also has a 1"mc in his crx with more aggressive pads all around and he never locks up any of his wheels, he's only on 205/50/15 azenis.



Any suggestions guys?

 

What type of pads and rotors are you using?

 

HPS' and oreillys lifetime rotors

 

what booster youre using?

 

99 integra gsr, 1"

 

hmm how bout brake setup civic calipers/rotor? integra calipers/rotor? oem big brake? aftermarket big brake?

 

front 99 ex civic calipers, o'reillys 1 year warranty brembo blank (stock size.. whatever it is) and HPS pads

rear: 99 gsr disk conversion with stock size slotted brembos and HPS' with stock rubber lines

 

its possible that the gsr 1" mc is pushing excess amt of fluid to the front causing the front to lock up sooner than it suppose to as oppose to the 7/8" and that swapping to bigger calipers ie integra may do the trick...? but im not sure if the ex uses the same calipers as the integra... what brake setup is your friend using in the crx?

 

Maybe time for an adjustable proportioning valve? Maybe dial in a little more rear bias?

 

my friend has the hawk blues all around on his crx, with 205/50/15 azenis and his brake pedal does not feel anything like mine when his pads are all warmed up. you can almost tell when his brakes will lock.. where as you can't in mine

 

stock rex calipers?

 

what kind of tires do you have?

 

Pads, MC's, and booster contribute to the feel of the pedal. I cannot see where this should lock of a wheel. I have used regular and 1" MC in an Integra, and changed to NSX calipers and rotors front, and upgraded the rear. All of this changed the feel of the pedal. I am better able to modulate the brakes and they cool better for track. The thread started about braking for a turn. Could you be unweighting a tire enough to lock? Yes, weight shifts forward, but, not equally if you start into the turn at all. Could it be either front depending on the turn direction? Or is there a difference in the caliper sliders? Have you checked rotor temps, is one side hotter and changing pad grip? I guess that I think of a local problem with what you described, vs say the MC, which should spread force equally.

 

What tires? Compound is more important than size. Has this only happened at one event?

 

i have 215/45/16 falken azenis, which when warmed up, still does the same thing. Pad wear for the fronts seem equal, as well as the rear.

Locking up will occur when i'm braking hard going straight (brake straight, turn hard..) even on the street when i'm dicking off i'll just gradually apply more brake pressure and eventually one wheel will just lockup.

could it be possible i need new front calipers? maybe one is not functioning quite like the other? All slides and everything are greased properly as well

 

Either wheel, not related to side of turn? If it is always the same side, check rotor temperature. Both sides should be about equal temperature if working properly.

 

yeah, just randomly either wheel will lock up. whichever gets more brake pressure i guess..

 

Since the system is hydraulic, it should get the same pressure each front. Does it lock if you do not turn? Could the lock come as you start to turn the wheel and have not gotten off the brakes completely?

 

Yes, it usually locks when i don't turn.. as when i'm turning at HPDE's i don't like to brake hard while turning..

 

You say your buddies pedal felt different then yours? I had a bad booster that made the pedal pretty touchy. It would depress about 3/4" to 1" and not really do much for braking. Then the next 1/2" to 3/4" would lock me up. So all my braking was in a very small pedal motion.
Alot of people told me that when a booster is bad you have to push the pedal really hard to be able to stop in that small range. However, I barely had to put pressure on it to lock up the front. Even going straight.

 

i know what a bad booster feels like, i've worked on plenty of cars where diagnosing is pretty simple. with it being like that would i be able to tell if mine is bad?

the difference between a bad brake booster from another vehicle and mine seems to be a big difference

 

when boosters go bad they leek so, i think it would make your pedal feel harder and it would take more effort, you might have to adjust your nipple/shaft thing sticking out of the mc ( i forgot the real name i don't have a book in front of me) that goes to the bb.

 

Sometimes you can hear air hissing or whooshing with a bad booster. They wont hold vacuum and get hard to push shortly after turning the car off..I dont think the booster is your problem..
The brake booster pushrod is to adjust the freeplay before the brakes actually start applying...There is a factory spec for this, but i dont remember what it is. If you have too much pedal travel before you get brakes, try adjusting this...
OP- You said if you hit the brakes going straight, both wheels lock up right? That kinda makes me think you have a sticking caliper(opposite of the wheel locking up). Have you tried a brake fluid flush yet?

 

Going straight, usually just ONE front tire locks up.


That's funny you said something about the hissing, sometimes my car makes a qweef noise after i turn it off. I remember my old buddy's 99 cx hatchback did the same thing and his brakes were horrible.


I will try adjusting the pushrod before i replace the brake booster i guess.. and Yes, since i autox frequently i flush the system every other month so it's always got fresh fluid in it

 

its the 1 MC thats doing it.