Ram Air Formula

I am having issues with the brakes and the pedal being soft. I have searched and tried many of the suggestions I found to no avail. The pedal is soft even with the car off and the booster vented. However, once the car is running the pedal is crap it is so bad. I've replaced the master thinking it was leaking internally. Now when I go to bleed the system the back bleeds fine. Pedal pumps repeatedly no problem. I get to the front calipers and I get one bleed out of it and then the pedal is dead. It takes a few minutes before the pedal has any life to it. In the mean time there is virtually no fluid being pushed through the lines and out the front calipers. To me this says there is air in the system somewhere. I have bench bleed the master twice now very well. I've tapped on it to release any bubbles. While on the car, I have even put the back end way up in the air so that the MC is leaning forward. No change in the pedal. I've smacked the calipers with a rubber mallet, again nothing. Pressurized the MC resevoir so that fluid is forced out the calipers, no change. Traditional pump a few times and bleed, yet again nothing. I'm lost. I do not see how this is messing up.

The ABS has been purged of air by engaging it on the street. Eventhough the pedal feels like crap, the car will stop and stop pretty well. Well enough to engage ABS anyway. However, the pedal was not this bad before. The rod coming out of the booster has been adjusted as well since the booster was replaced a little while ago too. So even though the car is stopping I still feel something is not right. That's what has led me to change the MC and bleed the brakes. However, doing that work has not changed anything for the better. No ABS codes either.

Any ideas?

Thanks

Oh this is a 95 factory big brake car

Da Mail Man

.....i'd say your m/c is shot, new or not!....i had an 81 vette that i would bleed the brakes and they would last maybe 2 weeks and then i noticed the pedal getting softer and softer and lower and lower....had no leaks, flushed it out, etc etc....i had a set of reman calipers and determined that something was "wrong" with the rears.....since i had a lifetime warranty, i took 'em both off and demanded 2 new ones, put 'em on, and had fantastic brakes since.......i determined that the system was SUCKING air each time i released the brake pedal ye, HAD NO LEAKS!!...somehow, air was getting back into the system....nonetheless, replacing the 2 rear calipers on my 81 "was the ticket"...

0Speed Hound

I feel that the system is somehow sucking air back in as every time the pedal is released during a bleed, I hear what I believe to be air being sucked in from somewhere, yet no leaks anywhere. I can get air to come out when manually bleeding, but the pedal never gets better. When I pressure bleed the system, I get no air out of the lines. I feel I have had way too much fluid pushed through this system to have air sitting somewhere waiting to be forced out.

Thanks

Da Mail Man

.....use the search function of this forum to get additional information for the problem you are having...also, if you plan on keeping the car, get a helms SERVICE MANUAL...........lastly, some people use speed bleeders to bleed the brakes.....

cv67

Hell yeah X 10 on speedbleeders, put mine in tonight-one of the best things Ive done. (size 10x1.00 from Summit)
Even though they have some sealant on them get a "joint stick" from a plumbing supply and put just a little bit on the threads so youre guaranteed no air sucking in. I kept it OFF the last 2-3 threads 9closest to the tip) fwiw. Barely gotta crack those suckers open for them to work...Love it.


I have a similar problem and have it nailed down to air in the front of the master cyl. I was told the manual says to diesconnect the wire on it, and bleed through the front line as you would bleed a caliper. Then once done, start at the RF, RR, LR, LF in sequence. I made good progress, excpet I cant find anyone to help me bleed the master thats local. I can see a tad of air coming up through the front reservoir when Im bleeding via the brake pedal.

Kinkajou

Ram Air Formula

Ok couple other observations.

ABS engages fine and responds well. So I don't see how I can still have air in that part of the system. Can someone matter confirm or reject that theory?

I now hear a vacuum leak when pressing the pedal or sometimes not pressing it at all. It's coming from the inside where the pedal is and responds to the brake pedal. Obviously this is the booster, but how can the booster be leaking and the pedal not be rock hard? Isn't the negative pressure(vacuum) area created on the front face(MC side) of the booster?

When bleeing the front calipers only, the fluid will suck back into the caliper when the pedal is released. Shouldn't the MC be drawing the fluid down in from the resevoir, not back up through the lines? This tells me there is still air in there somewhere. However, I have put a lot of fluid through this system(we are talking one gallon plus) and I get no air. The back calipers do not draw the fluid back into the caliper when the brake pedal is released. I can bleed the rear by myself by just putting the hose into some brake fluid in a container. I can not do this with the front.

Does this give anyone any more clues as to what the hell is going on?

thanks

cv67

I hav a similar situation and found it was air in the front half of the master cylinder only. Remove the sensor wire, have someone hold the pedal anc crack the line to the (front) master to bleed.

Also found no matter how tight I got the rear bleed screws they drew a little bit back throught the clear line. . Get some speedbleeders, that will fix that .

Z~max

Just a thought, is your Brake pressure warning light on inside? I replaced the bias spring on mine, bled the MC and calipers. Everything seemed OK except at times it seemed as if the fluid was not coming out of the caliper like it should. When I got in to take a drive the light was on. I pushed a couple of times on the pedal and it went out. By bleeding the brakes, the proportioning valve may think you have a leak and try to close off that end. Maybe it out of center or stuck towards the end you are having trouble with. I rebled the brakes, pushing and releasing the pedal slowly and waiting the 15 sec. in between bleeds while tapping on the calipers or MC. They are hard as a rock and with new Hawk HP+ pads, they work great.