Need Brake Bleeding Help (again)

[ObscureMachine]

okay,
Chevy conversion (kit from e-bay)
New MC (camper special 1 1/16" bore)
New hard lines on axle
New outer lines.

Everything is installed, tight, and not leaking. I bench bled the MC until I had no air bubbles. I "gravity bled" the brakes (letting the fluid run til it's clear). Fluid is clear, which I assume means the new fluid has gotten from the MC to the brakes. Then I used a vacuum pump to try to get the air out. But, the vacuum stopped drawing fluid and only draws air now. I've bled each wheel four times and I got no pedal and air coming out. MC is full. I've checked everywhere for leaks, but there are none. Any suggestion???

 

[byson1]

In my experience in the shop brake bleeding is a 2 person job. Open 1 bleeder valve (usually starting with the furthest one from the MC) and have someone push down on the pedal. Close the valve and then they can let up. Do this as often as needed until no air comes out of the line. Be certain the MC stays full. It may take a while but it's always worked for me. Also, be certain that the drum brakes are FULLY adjusted. I've seen people bleed brakes only to find out the brakes just need adjusting. BTW-I've never had much luck with the vac. bleeders, maybe other have. Good luck.

 

[Tito]

In my experience in the shop brake bleeding is a 2 person job. Open 1 bleeder valve (usually starting with the furthest one from the MC) and have someone push down on the pedal. Close the valve and then they can let up. Do this as often as needed until no air comes out of the line. Be certain the MC stays full. It may take a while but it's always worked for me. Also, be certain that the drum brakes are FULLY adjusted. I've seen people bleed brakes only to find out the brakes just need adjusting. BTW-I've never had much luck with the vac. bleeders, maybe other have. Good luck.

Grab a buddy and do it the only way that has worked for me, have him sit in the driver seat and pump it several times and hold while you open the bleeder, close, then he lets go and does it again. Keep doing this till no more foam or air, go around 2-3 times. Be sure to keep checking the MC for fluid...oh and be sure to put the MC cover on too...dont ask how I know this ;D. And as Byson said, make sure those rear drums are adjusted so you hear a tiny little scrape.

 

[ObscureMachine]

What Am I Doing Wrong???

Chevy conversion (kit from e-bay)
NO Booster (all manual)
New MC (camper special 1 1/16" bore)
New hard lines on axle
New outer lines.

so I have bled these brakes 7 times. No air at all coming out. But, I have to pump them at least once to get any stopping at all. The first push is soft, goes to the floor and just barely slows the bronco. I have to press twice to get any stopping at all, and then it's still soft. I bench bled the MC till no air was coming out. Do I need to pull the MC and bench bleed again? I'm just about to drop this thing off at a local shop and have them fix it!

It's beautiful today and I want to drive!

 

[blazinchuck]

is the MC designed for a disc/drum set up? I did the same set up using the stock MC...had to pump a few times to stop. I use a MC like to described and all is well now. Besure to check for correct adjustment on the rear drums...you could be losing alot of fluid due to worn shoes or bad adjustment.HTH,Chuck

 

[Apogee]

It's possible that you didn't fully bleed the MC...or that it's bad. I've fought bleeding my brakes for a good long while and in the end, it turned out that my "new" MC was bad from the auto parts store. I switched brands and problem solved.

 

[ObscureMachine]

It's a disc/drum MC. I guess it's possible I didn't bench bleed the MC enough. How do you know what's enough?

 

[ObscureMachine]

Ok, when the brakes are applied, the backing plate flexes (pushes away from the rotor). IS that right? Is the backing plate supposed to move?

 

[NYLES]

HMM?? thinking been long time since I worked on mine...and I dumped the backing plates. let me look at my pics

can you see whats pushing on it?

 

[ObscureMachine]

my backing plate is one piece. It's what the calipers mount to, so I don't know how I could dump them. It looks like the piston is pressing against the rotor, and the caliper is getting moved by the piston.

Do I need to do more grinding?

 

[kyle]

Did you go with a proportioning valve or are you still using the stock drum brake distribution block?

Have you replaced your center lines down to the housings (soft peddle could be due to old rubber lines)?

I had the same problem last week. I had replaced everything but these 2 parts replaced them solved the problem.

 

[kyle]

Also, are your lines to the mc hooked up correctly?

 

[NYLES]

opps!! chevy convert.....sorry was thinking Ford backin plates...me go think some more...

Me wishes me was there to help ya!

 

[Apogee]

my backing plate is one piece. It's what the calipers mount to, so I don't know how I could dump them. It looks like the piston is pressing against the rotor, and the caliper is getting moved by the piston.

Do I need to do more grinding?

Shine a flashlight from behind the knuckle...if you can't see light, you need to grind more. Your caliper mounting bracket should not deflect significantly when you apply the brakes, rolling or not.

 

[ObscureMachine]

Yes, still using stock distribution block. Didn't replace hoses from MC, but did replace everything else. Brake light hasn't gone off either since I've done the work, I don't think.

Your caliper mounting bracket should not deflect significantly when you apply the brakes, rolling or not.

I can't figure out why it's deflecting. I'm sure that flex is partially responsible for the soft pedal.

 

[ET]

How thick is the caliper mount? I've never seen the caliper bracket move when I had my issue. It's solid. Now mines round full plate,one in the tech writeup, not the the V style type.

I also suggest taking out the caliper when you bleed them so you are sure the bleeder is pointing straight up. I used some small sections of plywood inbetween pads. It got ride of a few bubbles in mine and fixed the spongy peddle. It still doesn't stop very well but peddle is solid.

Eugene