Please help me with my brakes

[katsi]

Lets see, I purchased a new master cillinder, hard and soft brake lines and callipers. Installed everything, bypassing the equalizer or whatever, and bled the system. I can not get any pressure to build up in the system. It does not leak and I am getting plenty of flow to each calliper. I purchased the master cillinder from Vics auto. I can only think that it is not working properly. Any idea why I can not get the system to build up any pressure? My foot actually hurts from pumping the brake peddle. I did use a bottle to bleed the brakes. Maybe I'm not doing it propperly. But, when I hook up a hose to the calliper and loosted the bleed scresw, the fluit starts flowing by gravity. I have pumped so much fluid through each line I can't immagine any air bubbles. Yes, I made sure that the resivouir was always full and did not suck any air. I am really at a loss as to why I can't get any pressure to build up in the system.

Some other notes.
Rear brakes seem to tighten after a good pumping - That does not sound right.
Front brakes never tighten up.
Absolutly not leaks in the system - found one and fixed.

[mbouse]

. Maybe I'm not doing it propperly.

as simply as i can state it:
1. all bleeder valves closed
2. fill the master cylinder reservoir with non-silicon dot 3 fluid
3. have an assistant sit in driver seat
4. you sit in front of one caliper
5. have assistant pump pedal 3-4 times and on the last pump - push and hold pedal (do not let go)
6. you open one bleeder valve until the brake pedal hits the floor
7. you close bleeder valve
8. assistant can now release pedal
9. repeat from step #5 until nothing but fluid comes out of the caliper

keep an eye on the reservoir to be sure that it does not empty, thus sucking more air in the system. advance to the 2nd wheel after all air bubbles are out of the previous caliper. by the time you have all four calipers completed, you should have brand "New" brakes

[katsi]

Yes, and although I do appreciate your help , I have blead breaks many times in the past and I understand the process. The problem her is - IF I COULD GET SOME PRESSURE IN THE SYSTEM, I WOULD BE HAPPY . THE SYSTEM WONT "PUMP UP" . Thus, the peddle ALWAYS goes to the floor . Their is no holding until the bleed screw is released and then peddle goes to the floor. The pedal will go to the floor WITHOUT releasing the bleed screw. I can't seem to get the system to pressurize at all and I am using the requirred dot 3 fluid. It acts as if the fluid is flowing back past the plungers in the MC when their is some back pressure. When opening the bleed screws, the fluid pumps through without any bubbles. I have sent a whole large bottle of fluid through each line and I don't see any bubbles.

[kilrwail]

Having (literally) just finished the same process, I can't add anything to Mike's description. But I can sympathize with your frustration. It took me several cycles at each wheel to ultimately get pressure in the system, probably due to air in the master cylinder. The lines may be full of fluid, but if there's air in the m/c, you have to keep pumping until it eventually comes out of a line. If you're getting fluid readily out of each bleeder just by opening them, I'd say your m/c is working, but still has air. I assume you have all four wheels off the ground with the car level? Put bigger construction boots on to save your feet.

[manoa matt]

Try and get the rear of the car higher or park with front end angled down. As the master cylinder is mounted in the car, it angles up slightly and it is possible for an air bubble trapped in the end. GENTLY tapping it will help to dislodge the bubble and get it moving.

Did you bench bleed the master cylinder before installing it? Its possible to damage the seals.

[katsi]

I think you guys may have something there with the master cilinder and the bubble. The car is off the ground and the rear is a bit higher. The front of the MC is slightly point down. That would explain the rear breaks building some breaking pressure but not the front as a possible air bubble in the top of the MC. I don't know, Thinking about it, I have the rear higher to make the MC level.

[rlux4]

Katsi, did you bench bleed the master cylinder before you mounted it? Even when bench bleeding it you need to tilt it into different angles so that all the air bubbles go to the top and get pushed out. If your master cylinder is not full of fluid you won't be able to get enough pedal to build pressure.
Ron

[narfire]

I still have a soft pedal after doing much of what you have done,however I do get the car to stop. After 3 MC's I got around to adjusting the acorn nut on the end of the booster as per IAP's tech bulliten on brakes. That made a difference as I was told the plunger inside might not have been comming back far enough to pick up the front brakes. Not sure about the reasoning but it did work and I can get firmer brake resistance,but I think a bit soft.
I also splurged on an order from IAP and bought a pressure bleeder,after modifying the cap, I have chased all the air out,I think.
I should have bought shares in a brake fluid company
I also did notice the mechanical part of a rear caliper was a wee bit damp when I pulled the rubber boot back.Perhaps the O ring is letting a bit of fluid pass. I have replaced with re-builts and will try when I get the axle back in.
I have no idea if all MC's have the same clearance to the booster acorn, but have a look.
I did't bench bleed my MC but should have ,perhaps I still have a bubble, but I thought a pressure bleeder would chase it out.
Good luck
Chris

[katsi]

Thanks for the info guys. Last night I took off the MC and bench bled it again. Re-installed and still had the same problem. I used a rented vaccume bleeder B4 removing the MC and that did not work either. I will have to look into the acorn nut. That could be my problem. The booster is probably shot as well. I also tried a varriety of different positions with the car. It's getting hot here in TX and was sweating my A@@ off jacking the car into different positions.

Here's an FYI for anyone needing a hand held vacuum bleeder. Auto Zone has one for rent. Basically, you buy the rental for 50 bucks and then they return the $ when you bring it back. Basically just a deposit on a loaner. They said I could have it for up to 3 months.

[narfire]

Try cracking the fittings for the front brakes at the MC. while slowly pushing the brake pedal to see if fluid is coming out. Be ready to close before air gets sucked back in though.(before releasing pedal) As the pedal is depressed,fluid should be comming out,if not check the acorn nut and clearances.

[katsi]

I just read an interesting article about the acorn nut . I will definatly have to let you guys know how that goes . By the way, how solid or failproof are the brake boosters? Can the be rebuilt? I can't find a kit anywhere except for the Alfa. Also, the booster looks a lot like the booster in the 134 - Any comments? And what about the replacement valves for the booster? Anyone ever tangle with one of those?

[TulsaSpider]

If your booster is bad the brakes will seem quite firm. I had a bad booster when I got mine and didn't know it was bad until it began leaking. I am following this thread I think it will be very helpful to others. The booster is not rebuildable. Good luck!

[Flyingthere]

I once thought I had a bad booster until I replaced the vacuum hose and found I had hole in the old one.

[katsi]

For 1968-1985 Fiat 124 Spider and Fiat Spider 2000, the following procedure MUST be followed to ensure safe brake operation.
1) Determine the depth of the concave opening at the mounting end of the master cylinder, and record the measurement

2) Determine the amount that the power booster pushrod protrudes past the mounting surface of the booster, and record the measurement
3) Adjust the acorn nut on the end of the booster pushrod to obtain a protrusion of .0325" to .0404" (0.825mm to 1.025mm). Be sure that the pushrod protrusion does not exceed dimension the master cylinder opening depth. There must be a gap between the booster pushrod end and the master cylinder concave opening.

FAILURE TO OBSERVE THIS PROCEDURE COULD RESULT IN BRAKE FAILURE!

You can get the diagram that goes with this on international auto's web site.

[katsi]

Can someone go here and tell me the difference between the 124 and the 131?
http://www.racepages.com/products/?uts= ... oster+fiat