Brake pedal stays down

[PaulTXChallenger]

I have read through the previous brake posts but not found my issue yet, although I have learned some new things.  My brakes were working fine until recently. '74 Challenger with front disc, rear drum, and power booster.  Now when I push the pedal it still stops the car just fine, but the pedal stays down.  I have to pull it back up with my foot. It will stop the car again next time, but again the pedal stays down.

I did find that the rear left drum cylinder was leaking some, and the right drum was only half working, so I replaced both rear cylinders with new ones.  I bled all the lines twice.  I had rebuilt the front discs this past January, so they are working okay.  The brake light on the dash is still on all the time (I'm not really clear what brake light is connected to).  With the new rear cylinders the car stops even better, but of course I still have to pull the brake pedal back up each time.

I'm not sure how old the rest of the components are in the brake system. Problem might be - MC, booster, proportioning valve? 
Thanks for any help.
Paul

 

[Chryco Psycho]

is the pedal binding at all ??
you may just need to lube the pivots ,
The next place I would look is at the booster , you can remove the master & see if the pedal still stays down , I had an issue with my Charger , someone had assembled the master with wheel brg grease & it started to stick on as well .
 there is a balance switch in the proportioning valve that trigger the dash light , often just pressing very hard on the brake pedal will recenter the valve , or you can crack a bleed screw slightly to lower pressure & it shoudl reset .
 Welcome BTW 

[burdar]

The booster should push the pedal back up.  First, do what Chryco said and make sure all your linkages are lubed and not binding.  My guess is that you need to get your booster looked at.  Even if the master is sticking, the pedal should still come back up.  The rod that goes in the back of the master doesn't lock into it.  Park the car until you get it fixed.

[PaulTXChallenger]

Thanks for the quick replies.  I lubed the linkage and worked it back and forth, and it eventually smoothed out.  So, now the pedal comes back up as expected.  Thank God for an easy fix every once in a while!

I still need to work on getting my brake light to rest, but this is progress.  By the way, I been reading this forum for the last year and half, and it has been a great help while my son and I have been working on the Challenger.  Thanks for insight!

Paul

[Bullitt-]

When I rebuilt the MC my brake lamp stayed on....studied the Service Manual & it suggested a quick hard depression of the brake pedal could reset the switch...worked for me.