brakes fade when car warms up

[onebadmopar]

got a problem  my car has drums all around i know i need an up grade but for now i have new wheel cylinders new brake lines have bled them over and over yet after driving the car a few miles  the brakes seem to fade away wich is a bad thing .. im wondering if the shoes could be contaminated they have been on the car for years but dont have much wear on them  any ideas would be a great help

[The70RT]

Did you replace the master cylinder?

[onebadmopar]

yes its a new master cylinder

[Back N Black]

Have you tried to adjust the brakes up a little more. 

[Charger-Bodie]

Do you have a brake line too close to a heat source? (exhaust)

[acelondon]

Power brakes? maybe less vacuum when warmed up. Check your lines, because i leak mightbe preventing the vacuum  from staying high enough.

i dont have power brakes at all, but i know my engine vacuum is high when the car is cold, then comes down after a while.

[bordin34]

Maybe the brakes are dragging on the drums a little too much.

[onebadmopar]

all good ideas im gonna recheck everything you all told me today and let you know how i make out leaking vacum line makes alot of sence i think thats the first place i,ll check what about proportioning valve can that be adjusted ?

[Steve P.]

Will the brakes fade away just sitting while the engine is running or are you talking about driving a few miles??

Brake fade is normally a problem when the shoes are adjusted too tight or you are boiling the brake fluid. Brake line too close to exhaust.

[onebadmopar]

it happens when i drive it a few miles

[Steve P.]

I suggest you careful drive the car till they start going mushy. Then quickly get out and feel each wheel hub for excessive heat. Let them cool off and get it home on jack stands. Pull the wheels in question and check EVERYTHING. It sounds to me like your drums are cooking and expanding when you hit the brakes.

If this is the case you will want to replace the shoes. Check the thickness of the drums. If you have plenty of meat you can resurface them. If not replace them. Make sure it all goes back together right. Including the adjusters going on the right way...

Let us know....