I have a 95 f350 with a 7.3 in it. The brakes are horribly spongy or hard. The guy I bought out from changed all the lines, pads, calipers, master cylinder, and bled the living day lights out of it. They are still the same. Someone told me that there is a problem with the stock brake booster on the 95's and a diesel models of the 350 just don't build enough vacuum to work properly. The 2 options are supposedly to buy some expensive booster, or live with it. I figured I know a place where guys can help me out with an answer and possibly a mod to fix what I have. So, what's my solution? Thanks ahead of time!

 

Spongy and hard are opposites. Which is it?

 

They do both at different times. Multiple problems perhaps?

 

When my brake booster went my brakes were so solid I thought I'd break my seat pushing so damn hard on that pedal.. Spongy sounds like either air in your lines still or bad master.. I'd inspect all lines for weeping before making any conclusions!

 

And rear brake adjjustment!
wont do anything for hard but spongy.also check the wheel cylinders.
or the vaccum pump could be going bad.

 

Did you bleed the RABS valve? If not, start over with bleeding, RR, LR, RABS, LF, RF. Def. adjust the rear shoes as said. There's also a Ford alternative booster called a "zero loss", which is supposed to handle the brake "fade" feel, where you get good pedal feel at first, but then the pedal loses its feel as you're holding your foot on it.

Stiff pedal could be vacuum pump, distro box, vacuum line or the booster. Does the red BRAKE(!) failure warning light on the dash work? Does it ever come on when you get the hard pedal?

 

I put a zero loss on mine and it seemed to help. Part number is F5TZ2005CA but like said above, could be your vaccum pump or Rabs. Also, I have bleed the heck out of mine at times and gravity bleeding worked best.

 

Hydroboost for the win!

 

I have thought about it several times but the making of the pushrod because you can't find one, rewelding the mounting pin on the foot pedal, etc. scares me off. One guy will say do this, another guy says to do that? Every link I read someone is having problems with something, I just don't want to screw mine up.

 

They are actually pretty easy to find. I used carpart.com and searched f450 brake booster. Then called the yards. I found 2 of them close for the trucks I did (west coast) I also did one by welding the pin on. That was a piece of cake. Used a old pedal and ground the weld off. Drilled hole and welded it back on. The old pin for vac brakes was ground flush and welded too. As far as hydroboost units I would not use the f super duty one and use the f73 motorhome unit. No need to change master cyl. Just bolt up the obs one.

 

I got ankle deep in my swap and turned back! lol I had the wrong unit and the mods would be more than my shade-tree garage could manage. Maybe someday... so i have a "spare" Superduty hydroboost in my garage. lol

 

Do your brakes feel right except when you hit them repeatedly a couple of times then go hard. Mine does that

 

Mine are just mush all the time unless I pump them. Last time I drive it I remember them being terribly stiff at one stop light, but this is a backup plow truck for my business and I have only driven it on the road 3x since I bought it. I spent most of the day today tracing a short in the snowplow harness, but now that I have that sorted out brakes are next. I plan on looking for that RABS valve and if that doesn't do it, I have a 97 f350 diesel I'm slowly working on too. I may grab the master cylinder out of that and see if the longer stroke on the MC helps. I'll report back when I figure out if either helps.

 

Ok, an update with more accurate info. Drove the truck today and it takes 2 pedal pushes to get the brakes to feel normal. The first push builds pressures so the pedal starts biting high enough that it feels normal on the 2nd push. When the truck is cold, the pedal is do hard that it feels like I'm going to snap the seat brackets pushing on the pedal, but after it gets warm, the 2nd push feels normal, just slowly drops. I'm wondering if I have 2 seperate issues. 1.) a brake booster on its way out, but works ok when it's warm. (Guess it could be a tired vacuum pump instead)
2.) something in the rear brake system that causes the sponginess.
My plan of action is going to be putting a plug in the rear brake line at the MC and see if the pedal stiffens up. If so, I know the problem is in the back and will be checking brake adjustment, RABS valve, and rear wheel cylinders. If it doesn't change, I'll hook up the rear brake line again, and plug the front line off the MC and see what happens. I can live with a tired brake booster if it goes away when warm. Does this sound like a reasonable plan, or am I missing something?

 

Cold issue could be vacuum pump or the booster. Do your HVAC controls operate normally when this happens? Similar thing happened to someone on one of the other forums, but we never heard back what it turned out to be. If you have a hand vacuum pump, you could use that on the booster when it's cold, and if you get boost instantly, then you can be pretty sure the booster is good and it's the vacuum pump that's acting up. If you don't get boost, then the booster is suspect.

Soft pedal that builds up on multiple strokes can indicate a bad M/C, one with an internal leak.