New Brake master and booster, brakes still not right

[6 Nebraska IDIs]

Ok, I installed 2 different new brake master cylinders and boosters over the weekend in my brown truck because of a faulty cardone one that I bought from advance. I ended up using one my brother had purchased several years ago and had sitting on the shelf. The 2nd one bled out fine and held vacuum as it should. But as soon as I tried driving it the brake light came one telling me the proportioning valve was no longer set correctly. So I fought that for over an hour and finally got the light to go out most of the time. However, I still have to push hard to get the truck to stop and then the light comes back on. I slammed on the brakes on a paved road and only the rears locked up, so its a safe bet my proportioning valve is still jacked up. I'm just not sure what to do with it. I've never had so much trouble with one before. I hate taking my vehicles to mechanics because 9 times out of 10 when I get them back theres always something else screwed up afterwords.

 

[bghnkinf350]

Have you checked the vacuum supply? The light will come on in a low vacuum situation.

 

[94f450sd]

are you sure you got all the air out of the lines?these fords can be nightmares in the brake dept.open the bleeders one at a time and let them drip for a couple minute.watch them and youll see the air bubbles come out.when its all fluid for a good 45 seconds or so close it and move onto the next one.go in order starting with the wheel the furthest away from the master.pass. rear,drivers rear,pass front,drivers front.

 

[BigRigTech]

I deleted my rear ABS valve, made my brakes MUCH better.

 

[6 Nebraska IDIs]

There's no abs in my brown truck since its an 83, but yea all our trucks with ABS are even more of a ***** to bleed.

I spent almost 45 minutes bleeding and re bleeding the brakes just to make sure that wasnt why the light was coming on.

I'll check vacuum again. Maybe you guys are right and just for giggles of making my day worse the vacuum pump decided to quit working at the same time a new master and booster were installed. You know, the trucks just trying to keep me on my toes.

 

[Brimmstone]

Does it have a ride height valve in the back. Went through hell trying to bleed on out once because the valve wasn't working right. Other than that all I can say is pass rear first, drivers rear next, then pass front and finally drivers front. You'd be amazed the people who bleed stuff out of sequence and run into problems. I would say to check your rear wheel cylinders since I know they will cause this but I doubt you want to even think about it with the rear end you have in it.

 

['94IDITurbo7.3]

Does it have a ride height valve in the back

what is that and were on the back is it located?

 

[lindstromjd]

Did you bench-bleed the master cylinders before you installed them? I learned the hard way once that brand new ones need it if they're going to work properly... actually made my brakes WORSE because I didn't know about it back then.

 

[mariner45]

The Ford brake systems on trucks of this era were/are known for regular problems.

With my 86 - I have literally replaced everything including all brake lines except the long rear line. Next on my list as it looks to be close to rusting through - 3/16" od.

I have had so much trouble in the past - especially after having the vehicle parked inside for 6 months, that I bleed the brakes each time prior to use. I put a litre of new brake fluid through each time and that seems to help. At least the vehicle is useable and safe.

mariner

 

[Brimmstone]

what is that and were on the back is it located?

It's a level actuated valve mounted just above and I believe forward fo the rear axle. It will look like a valve with a piece of bar stock connecting it to the rear axle. I don't remember what they look like as all of the ones that were on my trucks were removed immediately and plumped directly. What they do is adjust the amount of pressure your rear brakes will get depending on the load on the back of the truck.