Brake Issue

[bil1024]

Have manual setup with Wilwood setup and single reservoir , brakes worked fine and then one day the pedal went right to floor? Air in all lines now, everything looks tight, could it be the reservoir ?

[Alphamacaroon]

If the brakes were properly bled, and you had plenty of fluid in the reservoir, then AFAIK the only way air could get into the lines would be a leak somewhere. I seem to remember edwardb may have had an issue in his build where he had a bad master cylinder piston which I think resulted in a similar symptom, but I think he could easily see brake fluid leaking in his foot box. I'm sure he'll comment with more details.

You sure you don't see a leak anywhere?

[bil1024]

If the brakes were properly bled, and you had plenty of fluid in the reservoir, then AFAIK the only way air could get into the lines would be a leak somewhere. I seem to remember edwardb may have had an issue in his build where he had a bad master cylinder piston which I think resulted in a similar symptom, but I think he could easily see brake fluid leaking in his foot box. I'm sure he'll comment with more details.

You sure you don't see a leak anywhere?

Funny you mention that, front pax side had a leak but cannot find, though i saw the hose kinked at 90 degrees and will be replacing it, I routed it wrong. So possibly the root cause, not sure

[bil1024]

So put in new front lines and no difference I tried doing front and rear by them selves both act the same. Lastly I tried running hose from reservoir and no suction ? Any clue ? Maybe the push rods

[Alphamacaroon]

So many strange things here that it would make me think it might be best to get a professional to look at it. Only way to replace fluid with air is for there to be a leak, or for the air to have always been there in the first place. It could be a problem with the MC, but if that was the case then it’d be impossible to bleed them correctly in the first place, or you’d notice a leak. So it all comes back to improper bleeding or a leak.

If you remove the rubber boots from the MCs, do you see any fluid come out? That might be one way for a leak to “hide” for a while, but seems unlikely.

I’m not a braking system expert, but I can’t imagine any scenario where you’d have hard brakes one moment and soft brakes the next and the cause not to be immediately recognizable. I’d definitely have someone else who knows brakes take a look at it right away.

[edwardb]

If the brakes were properly bled, and you had plenty of fluid in the reservoir, then AFAIK the only way air could get into the lines would be a leak somewhere. I seem to remember edwardb may have had an issue in his build where he had a bad master cylinder piston which I think resulted in a similar symptom, but I think he could easily see brake fluid leaking in his foot box. I'm sure he'll comment with more details.

I did have a new Wilwood MC start a slow leak during my Coupe build after it was bled. Found a defective seal on the piston. Appeared be a defective mold of the o-ring. A $25 rebuild kit solved the problem. The bad seal was on the back of the piston. Not the front where the main pressure is held. So it never failed all the way to the floor.

[bil1024]

Update:

Yeah so found the issue, was damaged front brake lines, but dumbass me refilled it with power steering fluid! UGH, will need new M/C 's, any one have extra ?

[jwhit]

update:

Yeah so found the issue, was damaged front brake lines, but dumbass me refilled it with power steering fluid! Ugh, will need new m/c 's, any one have extra ?

take apart and clean out with brake cleaner should be fine

[Alphamacaroon]

Update:

Yeah so found the issue, was damaged front brake lines, but dumbass me refilled it with power steering fluid! UGH, will need new M/C 's, any one have extra ?

While power steering fluid is certainly bad and the whole system will need to be flushed and cleaned, it’s still a non-compressible hydraulic fluid, so the brakes should have felt perfectly solid even with the wrong fluid (at least at low temperature). So it’s still really important that you find the root cause.

You say that you found damaged front brake lines— I assume that means a leak? Did you find fluid on the garage floor? Also, didn’t you say that the rear MC was also soft? Sounds like you’ve made some great progress and glad you found the steering fluid mistake before it became a major safety issue! But the possible culprit still doesn’t seem to match the symptoms you described earlier (unless you or I missed something in your description). I still think it’d be a good idea for someone else to double check everything.

[bil1024]

While power steering fluid is certainly bad and the whole system will need to be flushed and cleaned, it’s still a non-compressible hydraulic fluid, so the brakes should have felt perfectly solid even with the wrong fluid (at least at low temperature). So it’s still really important that you find the root cause.

You say that you found damaged front brake lines— I assume that means a leak? Did you find fluid on the garage floor? Also, didn’t you say that the rear MC was also soft? Sounds like you’ve made some great progress and glad you found the steering fluid mistake before it became a major safety issue! But the possible culprit still doesn’t seem to match the symptoms you described earlier (unless you or I missed something in your description). I still think it’d be a good idea for someone else to double check everything.

Yes found leak on pax side front hose, it was kinked and fluid on the floor, replaced hose, then went to bleed and added the P/S fluid to the brake fluid

[Alphamacaroon]

Yes found leak on pax side front hose, it was kinked and fluid on the floor, replaced hose, then went to bleed and added the P/S fluid to the brake fluid

Gotcha! That makes more sense now. So the rear brakes seem to be okay? Or too soon to tell?

[bil1024]

I did have a new Wilwood MC start a slow leak during my Coupe build after it was bled. Found a defective seal on the piston. Appeared be a defective mold of the o-ring. A $25 rebuild kit solved the problem. The bad seal was on the back of the piston. Not the front where the main pressure is held. So it never failed all the way to the floor.

How did you slide in the piston properly, I tried sliding in the old one for practice and they tore ? Rebuild kit coming today, thanks

[bil1024]

Gotcha! That makes more sense now. So the rear brakes seem to be okay? Or too soon to tell?

Nope no joy there, I flushed all the lines, replaced the hoses, cleaned the reservoir and waiting on M/C rebuild kit

[edwardb]

How did you slide in the piston properly, I tried sliding in the old one for practice and they tore ? Rebuild kit coming today, thanks

It's been some months since I did that MC rebuild. So don't remember exactly. Put brake fluid on the piston, seals, and bore of the MC before assembly as I've always done with this kind of rebuild. Didn't encounter any issues. 1000+ miles on the build and brakes are working fine with no leaks.