89 K5 Bad Brakes after all new components

[IV Quattro]

I recently made the upgrade to 37's and 488s, the brakes have always been bad on my Blazer so I decided to chase down the problem and make it so I can actually stop when I'm in 4 low. I've replaced my Brake Booster, Master cylinder, front calipers, rear wheel cylinders, proportioning valve (PV2). And then I bled the brakes out really good until I flushed all the old fluid and the air out. My brakes still totally suck, my foot goes straight to the floor everytime I hit a stop sign. Am I missing something?

 

[rampage]

My first suggestion is to avoid hitting the stop signs by steering away from them.
But seriously, if your rubber lines are original that go to the calipers and the T at the rear then replace them. They might be expanding due to age. I’d use the braided stainless version to help eliminate that.

 

[Fastereddie]

If your pedal is going to the floor, you either still have air trapped somewhere or the master is bad. Obviously assuming you have no external leaks.
Just because your master is “new” doesn’t mean squat. Especially nowadays…

 

[IV Quattro]

My first suggestion is to avoid hitting the stop signs by steering away from them.
But seriously, if your rubber lines are original that go to the calipers and the T at the rear then replace them. They might be expanding due to age. I’d use the braided stainless version to help eliminate that.

The fronts are braided steel I'll look into the rears, would that affect it that much?

 

[Blue85]

and the air out. My brakes still totally suck, my foot goes straight to the floor ?

How can you know all of the air is out? Which types of bleeding did you use? IIRC, there is a C-clamp trick to hold the prop valve open when bleeding (i.e. search is your friend). It could be relevant with all of the stuff you've had open and replaced. Are the brakes basically stock or have you swapped axles or other components? If your foot goes to the floor, that's the problem, it should be on the pedal. If the pedal goes to the floor, something is wrong. Any brake component can leak. The only place a leak won't show up on the floor is inside the MC. Old swelling hose could be a problem, but personally I've never seen it.

Any other information? Does this happen to have RWAL?

 

[IV Quattro]

How can you know all of the air is out? Which types of bleeding did you use? IIRC, there is a C-clamp trick to hold the prop valve open when bleeding (i.e. search is your friend). It could be relevant with all of the stuff you've had open and replaced. Are the brakes basically stock or have you swapped axles or other components? If your foot goes to the floor, that's the problem, it should be on the pedal. If the pedal goes to the floor, something is wrong. Any brake component can leak. The only place a leak won't show up on the floor is inside the MC. Old swelling hose could be a problem, but personally I've never seen it.

Any other information? Does this happen to have RWAL?

I'm not sure what RWAL or IIRC means, the system is entirely stock, the front brake lines are braided so I've only got one rubber hose that could expand in the rear.

 

[Chickntrk]

If your pedal is going to the floor, you either still have air trapped somewhere or the master is bad. Obviously assuming you have no external leaks.
Just because your master is “new” doesn’t mean squat. Especially nowadays…

So true, I had to go through 3 master cylinders last year before I got a good one, don’t rule out new parts as bad.

 

[rampage]

I'm not sure what RWAL or IIRC means, the system is entirely stock, the front brake lines are braided so I've only got one rubber hose that could expand in the rear.

RWAL=rear wheel anti-lock
IIRC=if I recall correctly.

 

[1-ton]

If you have drum brakes in the rear they may be out of adjustment.

 

[Chickntrk]

If you have drum brakes in the rear they may be out of adjustment.

On this note, I’ve seen drum wheel cylinders suck air in but not really leak fluid out, just slightly weep..made the brakes impossible to bleed

 

[ZooMad75]

I agree. If the pedal is going to the floor it's still got air in the system. You should be able to stop on the street without it going to the floor even with big tires and deep gearing.

IF it does have Rwal you'll see a computer hanging under the master cylinder and the prop valve will be right there too. Typically the prop valve on a non Rwal truck will be on the front frame cross-member by the steering box. The Rwal prop valve is notorious for being a pain in the ass to bleed the rear circuit through. Mine was for sure. So bad I pulled all the Rwal crap out and put earlier squarebody parts in it to be rid of the crap.

 

[Fordum]

One other thing. You mentioned you replaced the front calipers. Slide under and take a good look at them. Is the bleeder above or below the hose fitting?
If the bleeder is below the hose, you have them on the wrong wheels. Swap them left to right and they will bleed out correctly.
I know there are a lot of models that will fit either wheel. But, not totally sure that yours is one of them. I'm very fuzzy headed right now due to turkey season.
So any advice I might give is suspect.

J.

 

[trukman1]

Another question. Did you buy a remanufactured master cylinder or a totally brand new unit? I went through three remanufactured units before saying screw it and bought a totally new MC. Problem solved. The remanufactured units can have a worn bore that the piston will hang up in and not work properly. ( Fluid bypasses piston.) Sad part was the new unit was only about $10 more than the rebuilt MC.

ETA: Spelling correction.