Foxbody brake questions need some help

[my89notchback]

Having trouble getting all the air out if my brake lines. I bought a power bleeder which worked, but when you remove it and replace the master cylinder cover, the pedal softens up again. Granted it pumps up after one cycle of the pedal, but still not right.

There are no leaks in the system. When the system is pressurized with the power bleeder, there is no decrease in gauge pressure. I'm stumped? I've also changed masters twice, changed front calipers, rear wheel cylinders and lines a few times chasing this.

1) Should there be any pre-load on the pedal pushrod? I have it touching when the pedal is at rest, but no load on it?

2) should the master cylinder lid have a vent on each side (this is a metal clamp style) or should it seal tight?

If anyone wants to take a swing at this thing, I'll pay you. I don't want to piss the summer away chasing this.

Chris
810-429-6446

 

[90SuperchargedLx]

First off dont use the power bleeder have a friend help you do it the old school way. keep bleeding it it took me a long time to get my brakes right when I did my rear disk swap with the 93 cobra master cylinder on my fox. also is the pedal soft to the point where it goes to the floor when you push it?

 

[Beigg]

Do you have the piston caliper pad plates in place? If those think plates are missing, it can result in a soft pedal. It is basically allowing the piston to push through the pad if that barrier of metal is mia.

Try gravity bleeding the system?

 

[Beigg]

Where are you located?

 

[mustangmike6996]

Jack up the rear and bleed the rear then do the same to the front. Then do it again with the car on the ground.


Sounds like the pressure bleeder is compressing the air bubble and when you release the pressure it expands and causes a soft feel.

Try a vacuum bleeder as well as having someone pump and hold the brake pedal.

Do right rear, left rear, right front, left front in that order. Furthest to closest for bleeding.

I have seen some people run a bit of preload on the MC pushrod. I cant remember the spec for the fox. I do know that the last fox I did a brake bleed on took forever!

 

[my89notchback]

Goodrich. I'll pay for gas.

 

[PHAT83]

rear drum or rear disc brakes are the rears adjusted ?

 

[my89notchback]

rear drum or rear disc brakes are the rears adjusted ?

It has the rear drums. They are adjusted out.

 

[my89notchback]

TTT. Nobody??

@Mike;

I'll try raising the rear of the car later today.

 

[OldbutNew]

MustangMike nailed it. Do NOT rely on the pressure bleeder as the do-all, end-all.
Go to the tried-and-true manual bleed. RR, LR, RF, LF. In that order.

 

[my89notchback]

MustangMike nailed it. Do NOT rely on the pressure bleeder as the do-all, end-all.
Go to the tried-and-true manual bleed. RR, LR, RF, LF. In that order.

We've been doing the tried and true for two months. The power bleeder was a last resort.

 

[OldbutNew]

What is the history of the master cylinder?

 

[my89notchback]

What is the history of the master cylinder?

New 1989 Ford Ranger manual unit.

 

[Rickety]

are the lines coming out of the MS 3/16??

 

[mustangmike6996]

The other thing is when bleeding the rear brakes, have the prop valve adjusted for 100% flow to the rear to help move any air.

Then do the same for the front.

Some of those lines look like they will harbor some air bubbles.

 

[Beigg]

the line going straight down into the bushing looks questionable. Are you using metric fittings with SAE lines? Are the fittings double flare or require a bubble flare?

 

[draggula]

Did you bench bleed the master cylinder?

 

[my89notchback]

Yes to bench bleeding the master. Did it twice because I thought it had air in it too.

The lines do not have crossed metric and standard lines. They are correct.

Yes those are 3/16 lines from the master to the prop block.


If I don't get it figured out this week, I have to have it towed somewhere so they can take a swing at it.

 

[my89notchback]

I'm proclaiming victory! Last night I tore the brake system apart and went old school with it. Went with the KISS method. Changed the lines and took the prop valve out. Since I had the line lock on the front, that became my splitter. The rear went from the master directly to the rear of the car. Eventually I will have to put in an adjustable valve to limit the rear braking, but for now it works, so I'm not messing with it. I also found that the pushrod for this master cylinder needs a hair if preload. As the pedal would come back, it would release the pressure. I discovered this after replacing the master cylinder cover because it was twisted from the factory causing a leak. Bad stamping. Nice quality control!!

WHAT A PAIN!!! Lesson learned. The fancy expensive stuff isn't always the best way to go.

 

[mustangmike6996]

Glad everything worked out!