I had great brakes before this track weekend. 1/2 inch of pedal travel and I had good break feel and pressure.

Now after this weekend, the pedal goes WAY down, almost to the floor, and doesnt give full brake pressure, maybe 1/3 at best.

It was after the first track session it started diong this, and got worse as the sessions went by.

Then I bled the brakes, and out of the left rear looked like ice cream coming out the bleeder valve!! But I bled all of the ice cream out until some pretty valvoline synthetic came through without air bubbles.


So, my problem is, I have way to much pedal travel after heavy duty brake usage, and I dont know what happend. I have lots of pad left, plenty of brake fluid, and just replaced the BB/Mc before the weekend.

Is my problem in the brake hoses? I dont have any fluid leeks.

 

but on the track I could give the brakes a little pump before the corner and I would get some good brake pressure, but this wasnt consistent.

 

does the car have ABS? If you get a little air bubble in ABS that can be a major pain to get out. This could of happened while you were changing the MC.

Another thing to check is for play in the hub/wheel. if it has play it can push the brake pads back a bit under hard turning, then your peddle feels real soft when you brake. Pumping the brakes slightly while on the straits will fix this, however it is a band aid fix.

 

nope no abs. my hubs are good im pretty sure

 

are you sure the mc is good? did you buy it new or used?

 

Did you bench bleed the MC when you installed it? You might have had some air trapped in there that was released under heavy use.

 

When you said "bled the brakes" does that mean a full flush on all four corners? Either way, do a full flush again and make sure your MC doens't accidentally suck in any air. Also, pull all your pads out and check for taper/uneven wear. Your pads may be pulling away from your rotors such that you have a long pedal before the pads fully engage the rotor.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by FlyZlow &raquo;</TD></TR><TR><TD CLASS="quote">Did you bench bleed the MC when you installed it? You might have had some air trapped in there that was released under heavy use.</TD></TR></TABLE>

no I did not bleed the MC. I didnt know you could do such a thing.
How do I do that?<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Another Drew &raquo;</TD></TR><TR><TD CLASS="quote">When you said "bled the brakes" does that mean a full flush on all four corners? Either way, do a full flush again and make sure your MC doens't accidentally suck in any air. Also, pull all your pads out and check for taper/uneven wear. Your pads may be pulling away from your rotors such that you have a long pedal before the pads fully engage the rotor.</TD></TR></TABLE>

Yes, I flushed out all four corners. i was surprised by all the moisture in the lines.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by FlyZlow &raquo;</TD></TR><TR><TD CLASS="quote">Did you bench bleed the MC when you installed it? You might have had some air trapped in there that was released under heavy use.</TD></TR></TABLE>

Bench Bleeding is most likely what you need to do.. . A racer by the name of "Budman" on here had the same problem. The MC was not properly bled. PM Budman, he's a pretty nice guy. Drives an SCCA, ITR classed Teg Type R.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drewbie &raquo;</TD></TR><TR><TD CLASS="quote">

no I did not bleed the MC. I didnt know you could do such a thing.
How do I do that?

Yes, I flushed out all four corners. i was surprised by all the moisture in the lines.</TD></TR></TABLE>

You use a soft line to loop each output of the MC back into the reservoir, then pump to circulate the fluid. Any air at the bottom ends up being pumped to the reservoir, where it is subsequently released. I've never tried it, but it was recommended to me by one of my racer/mechanic buddies for whenever you let the MC go dry or replace it.

If you had a lot of moisture in the lines, that could have been your whole problem. The wet BP of the Valvoline stuff is significantly lower than its dry BP IIRC. You were probably just boiling the saturated fluid. A flush with new, dry fluid might have done the trick. When I ran the Valvoline stuff, I would bleed a good portion of it out every single race weekend so that I always had at least 50% new fluid in the lines to disperse the saturation. I'm now running ATE fluid and I have neither bled nor boiled it in 3 race weekends, including a 90 min enduro. At $12/qt it pays for itself vs the Valvoline in my application because I don't have to bleed it nearly as often to keep it from boiling.

 

i noticed with the Xp10's, after about 60% of pad use the pedal gets more and more soft. ive heard different theories on this subject. i put a new set on this past weekend and the pedal was better than ever. Like you said it could be the lines. i could certainly use some new ones. put a new set of pads on there and go from there.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by FlyZlow &raquo;</TD></TR><TR><TD CLASS="quote">

You use a soft line to loop each output of the MC back into the reservoir, then pump to circulate the fluid. Any air at the bottom ends up being pumped to the reservoir, where it is subsequently released. I've never tried it, but it was recommended to me by one of my racer/mechanic buddies for whenever you let the MC go dry or replace it.

If you had a lot of moisture in the lines, that could have been your whole problem. The wet BP of the Valvoline stuff is significantly lower than its dry BP IIRC. You were probably just boiling the saturated fluid. A flush with new, dry fluid might have done the trick. When I ran the Valvoline stuff, I would bleed a good portion of it out every single race weekend so that I always had at least 50% new fluid in the lines to disperse the saturation. I'm now running ATE fluid and I have neither bled nor boiled it in 3 race weekends, including a 90 min enduro. At $12/qt it pays for itself vs the Valvoline in my application because I don't have to bleed it nearly as often to keep it from boiling.</TD></TR></TABLE>

dude I really wasnt kidding. vanilla Ice cream was coming out of the bleeder valve from my left rear!!!! No exadgeration!

where do I get a soft line? can I just hook a clear tube to the lines going to the proportioning valve?

I dont think that is the issue though. I will keep searching to find out though.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote"> noticed with the Xp10's, after about 60% of pad use the pedal gets more and more soft.</TD></TR></TABLE>

I have noticed this with several brake pads. I wonder what makes this happen. I normally have to junk the pads with 30 to 40% pad left on them.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 577HondaPrelude &raquo;</TD></TR><TR><TD CLASS="quote">

I have noticed this with several brake pads. I wonder what makes this happen. I normally have to junk the pads with 30 to 40% pad left on them.

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

CTbrakes.com (carbotech) has told me that their pads are good till almost the backing plates... almost = 1/16th" in my book b/c you never know when banana or irregular wear is going to hit.

I think the brake pedal travel is going to change with wear but the feel of the peddle once engaged should stay about the same. It shouldn't get mushy and go to the floor when you have 40% of your pad left.. .

 

well I got bored and decided to actually connect a soft line to one of the outputs of the master cylinder and give it a flush. I donno what good it would do sounds like a ricer prank to me but I couldnt tell if any air was coming out because the fluid would make bubbles soon as it hit the resivoir. but the bubbles seemed to be less and less with more flushing out.

 

you really think this bench bleeding operation is a joke huh?

 

YEah, because I dont have a p[ower bleeder

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 577HondaPrelude &raquo;</TD></TR><TR><TD CLASS="quote">I have noticed this with several brake pads. I wonder what makes this happen. I normally have to junk the pads with 30 to 40% pad left on them.</TD></TR></TABLE>

It's possible the brake fluid gets hotter when the pads are worn, and can boil. When the pads are thicker, there's enough pad material to act as an insulator, to keep the heat at the rotor rather than getting the heat absorbed into the hydraulic fluid.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nsxtasy &raquo;</TD></TR><TR><TD CLASS="quote">...there's enough pad material to act as an insulator, to keep the heat at the rotor rather than getting the heat absorbed into the hydraulic fluid.
</TD></TR></TABLE>

Insulator or heat soak?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Ponyboy &raquo;</TD></TR><TR><TD CLASS="quote">

Insulator or heat soak?</TD></TR></TABLE>

I think the proper term is, Heat SINK