Ok so here is the problem! I have a 97 civic LX with integra rear discs. and now when I when I put them in i bleed them and everything... so here is the problem...

when i drive around town there is not a problem, brakes feel like they should... stiff. But when i drive on the freeway for a good 10-15 minutes with no brake use, and i push the brakes and the pedal basically goes to the floor, i let off and then push again and it stiffens up... What could be the problem?

I just rebleed the brake system... got about 8 oz. of fluid and it was all black... now the pedal is kinda loose all the time, got some bubbles when i bleed them...

do you think that this could be cause by the wrong prop valve? I still have the prop valve from drum brakes in... why would this be happening?

 

Have you checked the rotor runout? I'm thinking that you may have something similar to a brake knockback issue. (This usually happens only in hard cornering when the rotor tilts from the stress and spreads the caliper.)

 

No... I do corner very hard, almost all the time... how do i check that...
can you define the terms and stuff... I am no noob, just unfamiliar with that

 

Put the car in the air and rotate the wheels. Look for wobble in the rotors, especially the rears. If you cannot see the rotors through the wheels, you must remove them, but your need to torque lugs (open ended) with washers for spacers onto the brake rotors.

I wan't implying that you corners hard, just that your symptoms could be analagous to brake knockback.

Another question is could you have an exhaust leak that is heating a brake line while driving on the highway?

 

hmmm... exhaust leak huh? very intereting... i DIYed my exhaust, so i will check that out.

Thanks

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by racer_X_123 &raquo;</TD></TR><TR><TD CLASS="quote">hmmm... exhaust leak huh? very intereting... i DIYed my exhaust, so i will check that out.

Thanks</TD></TR></TABLE>

Check where the exhaust is routed as well. If it is too close, it can boil the fluid. Just to confirm, does this ever happen at slower speeds?

 

only when the brake is not used for a period of time... normally like more than 10 minutes. but yeah, if i dont need the brake, then yeah, it will happen at slow speeds. do you think it has to do with the prop valve?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dogginator &raquo;</TD></TR><TR><TD CLASS="quote">Check where the exhaust is routed as well. If it is too close, it can boil the fluid.</TD></TR></TABLE>

sounds like you found the problem dogginator, a different version of hydrolock, for O.P that only usually happens when your going through a section of using the brakes lots, its boils the fluid and any water in it and the water(if any) turns to steam and expands in the brake line, which when you compress it just squishes down to the floor, depending how bad it is, thats why when you pump it again its ok, cause youve re-compressed it all back together again, in your case the long stint of straight line driving isnt supplying enough varying direction of air supply under the car to cool the spot being heated by your diy exhaust!

 

OK, just checked the area... no leaks found... i turned the car on and felt for leaks... none to be found... do you think it may have to do with this brake line i modifed to make the ones that came with the rear brakes fit... I dont want opinions on the fact that i made the line... just if this is a problem?

 

I wouldn't recommend leaving it like that because of rubbing. That should not cause your problem.

To check for leaks, put your foot over the exhaust tip while the car is running. It will build up pressure and announce any leaks quickly.

BTW: the proportioning valve should not cause a soft pedal.