When I hit my brake pedal it wants to go almost to the floor, but if I let go of it, it kinda seems a little sluggish with coming back up off the floor. Then I can push it again and get almost a full brake pedal. Any one might know what needs replaced?

 

try bleeding it first. also bad fluid can effect your braking performance. when you "pump" the brakes does it get firmer and more responsive?

 

We have bled about 2 or 3 bottles of fluid in the truck since Iva had it. Ya when I pump them the pedal feels firmer.

 

getting any bleeding anywhere? usually the back cylinders are the first to go. them relieving pressure will cause that. after you pump them a few times and the peddle gets firm again, how long does it stay that way?

 

Ive never replaced anything in the back for braking. I have replaced all the calipers brake hoses and the steel line going from one side to the other. Possibly its a back wheel cylinder. Never really did notice how long the pedal stays firm.

 

Got in today after eating lunch and took off and hit the brakes and they were REAL hard! After a few seconds I was able to push them in. I had someone tell me the master cylinder is possibly bad.

 

a bad brake booster or low vacuum will give you a very hard pedal

 

That was the first time it ever done that, maybe I tried to just take off to soon before it built some vacuum.

 

I would be careful the next while, it sounds like you will need to replace a booster or master soon, and to be honest, I've always had way better luck replacing them at the same time.

 

Usually a "double pump" scenario will yield:

A.) Wore/out of adjustment rear brake shoes. Pull the drums and see how much material is left on the shoes and make sure your auto adjusters aren't rusted (the threaded spur thing at the bottom of the shoes).

B.) Also peel back the rubber boots on the wheel cylinders to check for leakage. Any fluid dripping out of the rubber boots means replace the wheel cylinders.

C.) Wore master cylinder piston seal/bore. Replacing master cylinder will cure it.

If you have a really hard pedal all the time then:

A.) inadequate/none vacuum supply to the booster (21Hg of vacuum)
B.) tore diaphram in the booster (replace booster)

 

Both calipers are new, new brake hoses, and master cylinder.

 

Then I'd be looking at those rear wheel cylinders and shoe adjustment, if there is any shoe left.

 

I second the rear shoe adjustment. Plenty of times the rear auto-adjusters will break or rust over to the point of uselessness and then you have all this "slack" in your brake system, and the double-pump will pressurize the system enough to take up that slack. I had the problem on my 88 and my 89. Still do, I just manually tighten up the auto-adjusters every so often, works freaking great.
Only thing about that is that if there is a lip of wear on your drums it's a total PITA to get them off and on. I turned the lip off by putting the truck up on jack stands and running it in 2nd gear after mounting the drum on backwards; then use a third jack stand as a brace for a file and shave away!(think of it like a wood lathe and you get the picture) Haha, took longer to put it up on stands than to reduce the lip.

I was also going to say maybe your master cylinder is bypassing, which would manifest itself in the pedal slowly making it's way to the floor at a stoplight, but you said your master cyl is new, right?

-Joshua

 

I have the same problem, where my brakes are really hard to push in, i changed the vacuum pump but the problem is still there, Would it be the brake booster?

 

yea sounds like the booster if the brakes are very hard to push in