Start by making sure the rear brakes are properly adjusted. The shoes should
JUST slightly drag in the drums. Just slightly.
If you don't know how, I'd be glad to tell you.
Let me know.
That is the most common problem.
You'll feel more "pedal" too.

Try it first before you replace any $$$ parts.

Spdloader

<ralplas@aol.com> wrote:   (95 F150  230k Miles)

When I apply the brakes, the rear wheels did not stop
at all.    When I use maximum pedal pressure the rear
wheels will stop momentarily then release.  The shoes
are adjusted properly and the the parking brake works
perfectly.  Is this a proportioning valve problem?
_____________________________________________

More likely a failed seal in the master cylinder on the
piston that operates the rear brakes.   It has probably
been bad for a long time.   Install a kit or get a new
MC.  The rear brakes will share some of the stopping
load and the front brakes will last longer.

Good luck.

Rodan.

e

  I hope
someone can tell me what to do.

Thanks,
Harold

Getting old and mind is fuzzy at times but I thought  '95 had RWAL.
Your symptoms sound like a bad RABS valve which is located inside the left
frame rail
just foreward of the cab..Its mounted to the frame rail with three nuts, and
only has two brake lines going to it as well as a bleeder valve and a
wireing harness.   Bad Master cylinder is going to result in a low pedal.
The combi valve, , what you are calling a proportioning valve has four brake
lines and would be just under the master cylinder mounted to a bracket on
top the frame rail.  It's function is to hold off the front brakes till the
rear brake pressure builds enough to over come the return springs and start
to apply the rear brakes at which time it re-centers and allows the fronts
to apply.  It also regulates braking, typicaly 60% to the front 40% to the
rear on a rear wheel drive vehicle. It also acts as a safety device closing
off one end of the brake system if it loses brake pressure. They typically
do one of two things when they fail, they leak, or they get stuck and dont
recenter in which case the fronts dont do to much and the complaint is
generally poor stopping.  I havent seen them block off the rears unless
there was a leak at one point in the rear system.   If they get stuck you
typically have no brake fluid out the bleeders for that end of the vehicle
when you try to bleed brakes.  Sometimes you can get it to recenter and free
up by opening a bleeder on which ever end ofthe vehcle the brakes are
working on  and then hitting the brake pedal hard.  Still I would recommend
replacing one that got stuck but its a good diagnostic tool. If the rears
start working better you have found the cause.  But like I said I am pretty
sure 95 had RWAL.

Whitelightning

Are you *certain* you don't have rear ABS on this truck?  Even my old '89
F150 had rear ABS.  If it has rear ABS, there's some other gadgets
(accumulator, RABS valve) that need to be bled also.

You may not have adjusted the rear shoes properly.  This is a common
problem.  The shoes need to be the correct distance from the inside of
the drum.

You also need to ensure that you haven't accidentally installed the
adjusting mechanisms in reverse, ie. left side on the right, and vice
versa. They are *not* the same.  If you don't install them correctly, the
brakes will self-adjust the wrong way, and get looser every time they
ratchet.