Brake pedal goes to the floor.

[shmedley]

ARRGGG

I am having a problem with my 88 Lancer Shelby.

No matter what I have done with the brakes the petal still goes to the floor and has a spongy feel. I have replaced the calipers, front brake lines, master cylinder and one of the rear wheel cylinder. I have bled and bled and re-bled with both a mightyvac and the pump and crack method. The bleed fine but as soon as I start the car the petal goes to the floor. I have even pulled all the vac lines off the power booster with just the mail line going to it. I am stumped this has been screwing with me for a few weeks...

[mark]

i have dumb question. sorry.

you bench blead the master cyl right?

[turbovanman²]

Did you buy a new one or reman, if reman, go buy a new one. If new, see post #2.

Are the bleeders at the top of the calipers?

[shmedley]

Yes I did bench bleed the master. It was not a reman master.

[Turbodave]

Brad, Simon's got the right idea on asking you whether the bleeder bolts are on the top of the calipers, if you switch the left and right calipers accidentally, you'll never get them to bleed right, been there, done that...

[mech1nxh]

i have dumb question. sorry.

you bench blead the master cyl right?

another dumb question....have you verified the power booster
vacuum supply,c/k valve and pedal rod to m/c piston distance

[GLHS592]

I have replaced...and one of the rear wheel cylinder.

That is a big NO-NO. When replacing items in your braking system, ALWAYS replace that item on BOTH sides. Your other wheel cylinder may be leaking.

Don't trust the labels on the boxes either. I put the minivan calipers on my car according to the left and right on the box. A lefty was in my "right" box and vice versa.

[shmedley]

Yes both bleeders are facing up. (I have been there done that also). I only replaced one wheel cylinder because I screwed up the one side. The other side is dry. I do like to replace things in pairs but this was a screw up on my old mans account. (he pulled on the little boot to see if there was fluid in there and riped the boot).
One thing I did try (on a buddies hunch) was I put a vise grip on a front line (not very tight) and I had petal. He said because of that it could have been a frozen cailper but they both work and he did not know where to go from that.

[heavytank2]

Only time it did that to me was a leaking wheel cylinder. But I have heard of rubber lines balloning before causing the same thing.

[shmedley]

Ok heres an update. I took the car tonight and when I was coming up to a stop the brakes were fine when making a stop. But after I stoped the petal would go to the floor. I am stumped...

[turbovanman²]

Triple check your calipers-you narrowed it down to them and when I put on my 11 inch brakes, I had a bad caliper, it wouldn't bleed properly and the pedal sunk-you could see wetness around the piston and seal. Try clamping off the left side then right to further narrow it down. Barring that, if they check out good, you have a bad MC.

[shmedley]

OK heres a update again... It can/will lock the brakes up.
The petal seams like it wants to stop. there is a hard point when hitting the brakes. After it hits that point I can (with a little effort) push the petal further down and a hear a (for lack of a better term) squishy noise, it's kinda like a whoosh.

Thanks for the help so far guys.

[turbovanman²]

Bad MC.

[butchsuppe]

Did you bench bleed the master cyl ? sounds like you still got air in it. Try cracking the lines on the master starting at the rr while your asisstant presses the pedal + note if you get any fluid out of it. When ever you have this kind of problem you MUST verify the master hasn,t any air in it. Once you done this you may try gravity bleeding the sys. the possiblity of human error exsist by your assistant letting up on the pedal too soon when doing a 2 person bleed. I,ve had all kind of brk. problems working at Ford dealerships for 12yrs, which is why I,m now bald + 3/4 insane. One strange problem came in whereas a coworker couldn,t fix was a rotor was too thin, caliper piston seals are designed to withdrawl the piston and in this case the piston would travel too far thus causing the pedal to go to the floor. If you have drums at the make sure the adj. is OK. An indication of a bad master is a fluid guiser in the res. upon pedal release. ANYTIME a pedal sinks the the floor you have a problem that needs to be fixed, just hope you do before driving behind me. feel free to PM me if you on still having problems LOL

[Turbodave]

Sounds like the master to me also. I've heard that you can damage them somehow by bottoming them out when bleeding the brakes, so even the new one could be bad if that happened to it.

[Whorse]

Same thing happened to me. It was in fact the master cylinder like everyone is saying. People at shops kept saying wheel cylinder, and I think they're all scam artists. When the did the calipers, did any fluid squirt out when you popped them into place on the inner pad on the piston side of the caliper?

[DodgeZ]

Bad MC.

yeah. if it brakes good then goes to the floor it is prolly the MC

[shmedley]

Thanks for the help everybody. I will try to work on this weekend while I am not working. I hate having to work weekends!

[3nglenn]

Hey Brad- if you go to bleed the system again (the whole car) you might want to check on the tire to tire bleeding procedure. If it's like a Spirit you start with the right rear first, then go to the left front, left rear next, then the right front. I don't know anything about Lancers but I can't imagine they'd be different from Spirits or Shadows. Somebody correct me if I'm wrong. Good luck and keep us posted. G.P.

[mcsvt]

I was always taught to work from furthest away from master cylinder to closest. So RR, LR, RF, LF is usually the order. I could be wrong but this is always the procedure I followed.