Bkennedy's SAS and Rebuild Thread

[gmanpaint]

I didn't have to adjust the rod for my disc brake axle swap. Some have had to swap in a 95 master for the increased fluid volume and pressure needed when doing the swap from what I have read up on.

Just throwing another idea into the mix to give you options if the rod adjustment doesn't work.

 

[Four0Sport]

I didn't adjust the rod or replace master cylinders when I did the rear disc axle swap and never really had an issue until I went with 35s.. now I get a little creep on a steep hill if im not fully depressing the pedal. May swap in a 95+ master cylinder if/when I do the 5.0 swap.

 

[BKennedy]

I am stumped.
Brakes still don't work. With the engine off, I can build pressure and the pedal gets firm, but can still go to the floor with moderate pressure. Turn on the engine, no brake pedal pressure. Pedal goes totally soft and can be pushed to the floor with very light pressure.

I bled the brakes four or five times. Pulled the master cylinder and adjusted the push rod several times with no change. I even ran the rod out until I could not get the master cylinder to sit flush, then turned it back in until it sat flush. No pedal pressure when engine is running. No vacuum leaks, no fluid leaks, I don't get it.

If I run out and pick up the 1995 master cylinder, which one do I get? There are three; One is with cruise control and no proportioning valve. Two is without cruise and with a proportioning valve. Third has no cruise and no proportioning valve. I get the proportioning valve options, but not the cruise control. Why does the master cylinder care if there is cruise control?? Nevermind, jd4242 said I need the one with no frills

 

[gmanpaint]

Cruise has a sensor on the master is all.

Your 94 has the abs pump. There can be air trapped inside it and a normal bleeding won't work.

I would try a power bleed from the rear right corner with a gravity bottle filler, or a helper to keep the resi full. If that doesn't work, than a slow gravity bleed for a few hours might.

If neither work, than the OBD brake computer bleed might be needed.

The pressure will build and you will get a firm peddle with engine off but as soon as the system is engaged with engine on, the abs pump will cause the peddle to fall if it has any air trapped

This is what it sounds like is happening to me. If the booster, one way valve, or the wheel cylinders were bad, you won't get a firm peddle with engine off.

If you slowly lose pedal, it might just be a slow leak.

If the master was good before any of this build, chances are it is still good.

 

[BKennedy]

Cruise has a sensor on the master is all.

Your 94 has the abs pump. There can be air trapped inside it and a normal bleeding won't work.

I would try a power bleed from the rear right corner with a gravity bottle filler, or a helper to keep the resi full. If that doesn't work, than a slow gravity bleed for a few hours might.

If neither work, than the OBD brake computer bleed might be needed.

The pressure will build and you will get a firm peddle with engine off but as soon as the system is engaged with engine on, the abs pump will cause the peddle to fall if it has any air trapped

This is what it sounds like is happening to me. If the booster, one way valve, or the wheel cylinders were bad, you won't get a firm peddle with engine off.

If you slowly lose pedal, it might just be a slow leak.

If the master was good before any of this build, chances are it is still good.

No more ABS. All the ABS brake parts (pump, relays, controller, etc.) are sitting in a box in the back yard.

 

[gmanpaint]

Slight overlook of the abs delete. My bad.

 

[Kirby N.]

Still sounds like trapped air. gmans bleeding suggestions would be what I would do. It sucks not having brakes so you can't drive it to a shop and have them powerbleed it for you.

 

[BKennedy]

I am going to get the 95 master cylinder, then do the slow bleed process with that. I am out of time so I am going to throw money at it and see what happens. If that doesn't work, I will have to button it up and get it on a tow truck to a brake shop that does custom work, since I doubt any of the chain shops will touch a frankenbrake setup. Besides, I know more about brakes than your average chain brake shop mechanic.

 

[FR-425]

Hey BKennedy,

Here's a ABS bleed trick:

If you have an old front rotor. brake off a few of the signal fins with BFH.

Put this one broken rotor on and drive along slowly with light brake pressure.

The "dead" spot will activate the ABS every turn of the wheel. You'll hear it loud and clear!

This will get fresh fluid into, and AIR out of the ABS block.

Keep a close eye on the fluid level, if the system has been open a while it'll drink it up quick.

 

[BKennedy]

No ABS to bleed, but thanks. Might try that on the other cars if needed.

Replaced the 94 MC with the 95 (you can use the one with cruise control, just get a 3/8" plug for the port). Bench bled it, installed, bled all the brakes. Prior to installing the new master cylinder, I put the push rod back to its stock settings. Engine off, pedal pumps up very firm, like never before. Engine on, pedal to the floor with no pressure.

I called my mechanic relative. He lives across the country but he walked me through a bunch of steps which ended under the dash with the engine running and the phone on speaker. When I pressed on the brake pedal several times he asked if that was air he heard. It is, the pedal makes whooshing sounds when pressed. He said that since I replaced everything else, it sounds like the booster was on its last legs and the diaphragm blew. There should be no air noise when pressing the pedal with engine on. Off to the parts store, again. Should be interesting to see if my measurements were right and I have clearance to get that sucker out around the shock hoop.

 

[gmanpaint]

That whoosh of air is just the one way valve doing it's job.

I just double checked on 2 dif explorers, they both do it.

Do you have a rear adjustable prop valve?

 

[FR-425]

OOOH, You were serious when you said the ABS junk is in the back yard,

My bad.

 

[FR-425]

If it gets all crazy trying to get the booster out just pull the vac line, plug the vac tree and drive it no power brake style. Should be fun with all that rubber to stop!

 

[BKennedy]

I just got off the phone with the senior technician from M-I-T in Santee. They do all kinds of disc brake conversions for early Broncos, and they did the axle work for my SAS. While there with the axle, Jeff spent several minutes with me going over shock mount options. He was very pleasant and really knows his stuff.
I told him my problem with the brakes. He had me measure the bore size of the master cylinder (1-1/8"), which is what he recommends for F-150/Bronco front brakes and Explorer rear discs. He says the brake booster (newly replaced, no change) is doing its job. Jeff says there is either more air in the system, or I have a leak. There is nothing else it could be. He suggested something very simple might be the problem. The front Ford calipers sometimes have a bleed valve which is not at the top of the caliper. I need to turn the caliper so the bleeder is at the top, put a piece of wood inside the caliper to keep the piston from moving, and try again. I will let you know what happens.
I am glad he called and gave me more options because I was about to light the stupid thing on fire and go buy a J&*p (ok, not really).

 

[BKennedy]

That whoosh of air is just the one way valve doing it's job.

I just double checked on 2 dif explorers, they both do it.

Do you have a rear adjustable prop valve?

Thanks, for the information. You are right because it did nothing. My measurements for the coil over hoops were off a little also. It was a major mission to pull the old booster out. I ended up beating a dent in the booster and spreading the shock hoops slightly with my Hi-Lift (is there anything they can't do??). I cut 3/4" off the studs of the new booster and it cleared with no problems.

 

[gmanpaint]

All good.

I went thru this exact same situation, and I felt the same. I was beyond frustrated over it, because it is a simple system, and why I couldn't figure it out, was killing me.

I ended up having too much rear pressure causing the master to bypass and pedal failure. That took months to figure out and I replaced the entire system with multiple masters in the process. I did find that I had 2 right side rear calipers installed, so one had a bleeder under instead of over. Easy problem to rectify.

I was just trying to help you avoid all that, but at the same time, trying not to irritate or feed fuel to your fire already burning. If you have a leak, I would check the new flares first, than every connection. A helper to work the pedal while you look for bubbles would be great. Wishing you luck running it down!

 

[BKennedy]

So, what did you do to fix it??

 

[Rick]

Some people swear by a residual pressure valve when adding rear discs. I didn't use one in the Explorer, but I did need it in the '60 Dart. I went through the same thing, until I added the valve. Didn't want to mention it since it wasn't something I needed on my own Explorer.

Are your rear discs from an Explorer or are they the GM calipers that come with the aftermarket kits?

 

[gmanpaint]

I installed an aftermarket adjustable prop valve and eventually set it to 450 lbs(started at 600 lbs). The rear pressure was mostly to blame for the pedal failure.

I made all new double flares on every line end I had made, and used Teflon tape on all the flare nuts on everything. Replaced the rear line junction tee, made sure the lines were all going downstream (height wise). Slow gravity bleeding with clear catch bottles & tube to the bleeders, with a gravity fill bottle worked the best for me. I bought a power bleeder, but that was just a pain to use.

If your willing, and if your rear lines are "newish", there is a simple test to see if the front or the rear is the issue. For the most part the front & rear are 2 separate systems sharing the master. Take 2 small vise grips, and lightly crimp the rear soft lines on each caliper. Test the pedal to see if it will hold pressure. If it holds, you know the leak is at the rear, if not, the leak is at the front. This is how I discovered where my problem was and gave me a starting point to fix. Simple test shared with me from a mechanic, and a member subscribed to this thread.

 

[BKennedy]

Ahhhhhhhhhhhhh, this may or may not make me sound like a moron;

I got it fixed and it was obvious. I called BC Broncos to say great things about their track bar and steering kits, and ***** about their leaking brake lines. The tech guy was apologetic. I told him about the issue I was having with the brakes and if they ever had any problems with the T-Bird calipers not bleeding properly. He says, "Only if they are on the wrong sides." Goes on to say the calipers have the brake line inlet and the bleeder valve on the top. If you put them on the wrong sides, it looks right, but NOT, NOT, Frigin NOT!!
So we share a laugh, like most of you are probably doing right now. I get off the phone, swap the calipers, bleed the brakes and holy moly, I have pressure. Its still not great, but it will work. I have Sarah press on the pedal while I look over the front brake lines. The lines from BC Broncos are leaking at the fittings, again, and the stainless front brake line that I got from Bronco Graveyard (http://broncograveyard.com/bronco/i-12535-stainless-steel-front-brake-line-extended.html) is leaking at the crimp.

Jeff at MIT says he should have all the parts to replace the faulty stuff I bought on line. I pulled the brake lines and will be there at 8AM.
Now, all I need to do is clock the transfer case, replace the brake lines, bleed the brakes (one more time), and take it for a test drive. Should be done tomorrow.

Thanks again for all your help. This is a great bunch of people, who really try to help those who mostly need help from themselves. I am my own worst enemy