1995 f250 5.8 These brakes have got me stumpted,Everything is new now over the past 6 months that I have been screwing around with this thing.STILL the pedal is hard as hell and the truck barely stops.What in the world is going on?

 

Everything new? Including the vacuum booster?

 

yes it is.And sunday I replaced the last old brake line and bypassed the abs for the rear.

 

Do you have good vacuum to the booster? How's the vacuum check valve?

 

ton of vacuum and the check valve is good,It wouldnt hurt to check valve again.

 

if u loosen the lines at the master will the pedal soften up mayby a blockage somewhere in system

 

yes,when I bleed the system the pedal will be soft and go to floor

 

How much vacuum do you actually have? Check with a gauge.

Also, just because you replaced the booster doesn't mean the new one isn't bad, too. Especially with cheaper units.

 

I will check,do you know how much the booster requires?

 

One thing I discovered (by accident) at work was that if you over-tighten a brake line, it can block off flow. I tried forever to get fluid out of the rear wheel cylinders, nothin. Another tech loosened the line to the flex hose just a little, got all the fluid in the world. Verify you've got fluid at all 4 wheels, then I'd say its a booster issue

 

I would say booster as well.

 

Vacuum to booster should be the same as manifold vacuum, 18 to 22 inches give or take a inch or two at idle.

Do the brakes work as they should other than the pedal being hard?

 

Everything checks out,fluid to all 4 wheels,and besides the hard pedal there is no stopping power either.Just bleed the brakes again tonight.

 

I am beginning to wonder if the new booster is either to small or something.Is there a difference in boosters for single piston vs. dual pistons in calipers?

 

Have you tried bleeding the system with the truck running?

I've done this in the past for vehicles I had problems with getting all the air out of the system. I know that isn't your problem, but you can definitely tell if the booster is working or not. It should blast fluid out way harder than it does without the truck running.

I believe all f250's had dual piston calipers in our year range, don't know that for a fact though. I do know there is a difference in the master cylinders depending on whether or not you have cruise control, at least for some years, but I think its just a pressure cut off sensor.

I also don't know if you could bolt an f150 booster in there as I have never tried. I would guess not, but even if it was possible I would think it would give some power assistance and it doesn't sound like you are getting any.