I have a 71 F-100 4x4, 390, c6. I just replaced the rear shoes, springs, drums and wheel cylinders. Fun job!!! I am trying to bleed the rears and I get no fluid. The front drums are also locking up a little. Only the front reservoir of the master cylinder goes down when I bleed. I am thinking it is the little valve in the proportioning valve is not centered. Can anyone tell me how to re-center it? Can I remove the fitting and grab it with some needle nose? My brake warning light is not hooked up either..
Thanks!

 

Needle nose no, but it you decide to take the end pin cap off here it what is looks like. A piece of wire might work, smaller than bailing wire.

Also you have to either pull and hold the pin out or in based of GVW...when bleeding the brakes. It onlt moves like 2 or 3 16th not no 1/2.

I have heard a good stomp on the pedal will work too.

 

Welcome to FTE!
Why did you change the rear brakes? Were they working fine just worn out or could the M/C been bad so it appeared to you that it needed brakes? Have a buddy move the brake pedal back and forth for you and see if you see movement in the fluid of both halves of the reservoir.

 

But just better be prepared for fluid to come up any where from a few inches to hitting the underside of the hood.

Put on your on some safety glasses as it's no fun getting B-fluid in you eyes.

Since yours is a 71 you should only have the little brass the proportioning valve block those don't shut off the fluid flow like the ones used in later yrs.

Loosen the rear line on the proportioning valve and see if it starts to dip fluid. Now the M/C front well goes to the front brakes this is the one facing the M/C. The smaller m/c well is for the Rear Brakes Okay.

Those proportioning valve are not ez to get reset with yrs of buildup of crap that causes them to be frozen the slider trip rod. But can be done by using your M/C line in & lines out plugged out then bleed air out, then push as hard as you can on the brake pedal.

Have the brass end plug out and covered with a rag to catch any fluid plus parts if your lucky. If not then you'll have to finish pulling the little rod out.

Then clean it being careful not to damage the 2 o-rings on each end. I used a soft bore brush to clean the inner bore. Good luck
orich

 

I replaced the passenger side rear wheel cylinder because it was leaking.
I wasn't going to do just one side. So I replaced them both.
I had heard if you open the front bleeder while stepping on the pedal it may "re-center" the piston in the distribution block. I did that and now I have only a trickle of fluid from the front bleeders as well! No pedal what's so ever and just a trickle of fluid out of any bleeder...Help!!!!

I hope to replace the distribution block this weekend. Besides just start replacing parts i.e. master cylinder, brake lines, I am kind of lost.

 

Orich: It is just a brass block as well. It does not look like the pic above. You're right.
So if there is no piston inside to re-center why am I getting only a trickle of fluid at all 4 bleeders?

 

Add more B-fluid let it flow for until all air is out.
The brass one's we have the centering the rod freezes up and is hell to get out and cleaned with out damaging the orings...

This was why I got this NOS one.
I have a brand new one NOS from a Ford dealer the was closing selling off the stock.. If your interested, it even comes with the new trip switch..
I ended up doing a big change with my B system so don't need this nos one.

here my email if interested in price.
orich1@hotmail.com
STILL IN UNOPEN PLASTIC BAG
I'm pretty sure the f100 & f250 is the same P/n c8tz-2b257-c

 

I'm interested in the prop valve if it's still kicking around.

 

Old trick that sometimes works:1. Master cylinder full of fluid. 2. crack loose fittings attached to MC till a little fluid drips out. 3. Retighted fittings.
This method sometimes equalizes pressure in the valve and letts the internal piston recenter itself...it can't hurt and it's worth a try.

 

I did that with my 68 Mustang... But I wrapped a rag around the PV and gave the brake pedal one good stomp and the brake warning light went out. 'tightened the fittings and it was all unicorns and rainbows.

 

A 1971 F100 won't have a proportioning valve. That is one component found in a multi-function brake valve, first used on the 1973-up model trucks with discs front/drums rear.

No F100s prior to 1973 came from the factory with front disc brakes. Discs weren't optionally available on the trucks until 1968 and that was only on the F250 and F350 models. In the case of these models, a pressure differential valve was used along with an inline, stand-alone metering valve plumbed into the front brake circuit.

In the case of your F100, it would just have a pressure differential valve with no metering valve for the front brake circuit and no proportioning valve to the rear brake circuit.

If the first brake circuit you opened was the rear, then you created an imbalance in the pressure differential valve, when you finished the rears and started bleeding them out.

The rear experienced a lower pressure (differential) compared to the pressure on the front brake circuit. The higher pressure side applied more pressure on the end of the pressure differential valve spool and shoved it to the low pressure side (the rears).

You will have to re-center the valve. Here is the procedure directly from Ford's instructions on how to re-center the pressure differential valve spool.



This is what the inside of the pressure differential valve on your truck looks like (upper part of the page).

 

Great info...THANKS!