Customs brake problems

I have a 54 ford with camaro Disk on the front and camaro drums on the rear.
looks like a 1975 granada master cyl.with a proportioning valve.
With NO brakes on the rear The brakes are bled. wheel cyl are good and brakes are ajusted.
I don't know why they used a granada cyl.
Why no brakes on the rear?

 

Did you set your shoe drag?

 

Yes

 

1. Pedal throw.... The op rod is not going fully into the cylinder. It goes enough for the front but not the rear. Look in to how the pedal is set up.
2. Incompatible parts...volume problem That master may not be able to supply the volume. Research the master as far as size as well as the GM calipers and wheel cylinders. You may have to go with Camaro/GM master engineered for "Camaro System".

 

I think i will try a Camaro MC and see if that helps.

 

When you say no brakes in the rear, can you clarify that? Is the pedal low and spongy or is it firm and just not stopping?

 

Could you pop a drum off and take a picture?

 

Have you checked to see if the "proportioning valve" is centered? That is more likely a "combination valve". I seem to recall that when there is a failure in either front or rear circuit, a "shuttle valve" inside moves to block the p***age to the failed system. I believe when that occurs, that side of the system no longer receives fluid from the master cylinder until it is reset. If I am correct about that, the Ford Factory Shop Manual will describe that function and how to troubleshoot and reset the shuttle valve.


Ray

 

Yeah, post a picture of that proportioning valve.

 

When i jack up the rear of the car and put it in gear the rear tires spin with on drag

 

When bleeding the rear brakes, is there a strong flow of fluid when the bleeder is cracked? Or just a spurt.

 

That would be the first thing I would do, check that the master is being pumped fully with each pedal stroke ( see post #4) and make sure that you are getting fluid to the rear ( have someone push the pedal while you open the bleeder valve).

I have seen proportioning valves screw up too, that could cause you a problem.

 

IMO, blaming the master cylinder itself is way premature here. There are several things to check
before one can say with any certainty that it needs a master cylinder.

Ray

 

I removed the guts from the proportioning valve.
Adj the rear brakes up and bled the rear brakes
Got a large amount of fluid with someone (wife)pumping the brake pedal.
still no brakes on the rear.
Also tour one wheel cyl apart and found nothing wrong.
stumped.

 

Have you checked this?
The rod may not be going deep enough into the master cylinder to fully apply the rear brakes.

 

Thanks But I checked that also.

 

Everything cannot be 'OK' and the brakes still not work. Something fundamental has been overlooked.

Ray

 

I understand that but it is a custom and to remove the rear wheels
I have to remove the rear shocks to drop the rear enough to clear the tires.

 

Maybe something fundamental like Does the section of the M/C feeding the rear develop any pressure? Or does it just push fluid when the rear bleeders are open?

 

so, did this system ever work? was it a non-running project when you got it? how do you know the make/year of M/C? you removed "guts" of proportioning valve? a few pictures would really help. Hnstray has given good info on the proportioning/combination valve possible failure cause. recently someone else here lost rear brakes because the brake line T attached to rear differential housing came loose. done any research to compare a Ford disc/brake system to a Chevy? have any different requirements? was the original '54 Ford brake pedal retained?

 

The car is a running driving car . stops just fine on the front disc.
all i can find out is its a 79 tbird M/C .
Proportioning valve is located where you cant get a picture of it.
brake pedal looks like 54 ford
I"m lost , ready to eliminate the Proportioning valve
and start fresh.

 

Are the brake lines going to the correct end of the M/C? Typically, but not always, the rear lines are attached to the outlets closest to the brake pedal.

If you gutted the proportioning valve it shouldn't be effecting rear brake pressure.

 

plug the rear brake port of the master, if it is hard that will eliminate the master.

 

Do you have a functioning E-brake ?? If so , will it stop the rear wheels ?? If not , it could be simply a matter of adjusting the rear brakes..
davfe

 

True, and the most logical place to start as well.

I bought a new F-150 in 79 and drove it daily for 15 years. Two different times during its life, one section of the m/c failed totally and with no warning. Like the truck stopped normally and then at the next stop the pedal hit the floor. Couple pumps and the still working section picked up and allowed me to stop. One half of the cylinder working fine and the other half doing nothing. Replaced the m/c each time rather than rebuilding, so it wasn't some defect peculiar to the original cylinder that caused it. Been driving for 48 years and never had anything like that happen on any other vehicle.

 

79 T-bird master cylinder

 

Argh...if the master looks like the one in the pic posted by Ricks Garage then the fronts should be plumbed to the larger reservoir...unlike what I said in my original post....what was that about trying a Camara M/C???