Smoking Brakes - Any trouble shooting suggestions?

I've got a 64 Impala with smoking brakes and I'm looking for help in diagnosing the problem.

I've currently got a manual disc-drum set up.  I recently replaced the worn out master cylinder (drum-drum) with a manual disc-drum (deep cup, large disc/small drum reservior).  While replacing the MC the peddle push rod seemed to be too long and I had to resort to partially bleeding the rear brakes to allow the MC spool to engage.  The pedal is very stiff and the MC spool is depressed even though the

After about 100 miles of use, the rear drums started smoking.  I thought that the drums just froze up.  So I pulled the drums, cleaned the backing plates and replaced the shoes.  I thought that it was really odd that the drum that was acting the worst came right off.  I didn't have to struggle with prying it off.  It was almost like the brake had never been hung up.

I found upon my test drive, that now both front and rear brakes are smoking and it feels like the brakes are on while trying to accelerate.

So, I'm now thinking back to the new MC and the push rod.

Do I need a shorter push rod?  What is the acceptable amount of compression of the MC when the brake pedal is not compressed.  If the push rod needs to be shorter, can I modify my existing  pushrod (cut to length and grind)?

Is there a check valve in the MC that is not releasing pressure on the brake?  Does this need to be removed?

Ideas on this cause would appreciated.

Mike  

the master cylinder piston should not be pushed in at all when the brake pedal is at the upper stop...

as a temporary test.. put some flat washers behind the master and bolt it back down..

i would also like you to verify that the parking brake cables are not binding..   i have had the grease dry up and stop the parking brake cable from freely moving with just the spring tension on the end of the cable...

i have disconnected them... cleaned the forward part... pulled the cable with grease on it back and forth... till it slid easily...

one more question..  it has been decades since i was under the dash of a 64... is the pedal against the upper stop.. or the brake light switch...????/   |-----  i have on other cars had the brake light switch hold the brake pedal down slightly.. keeping the brakes on...  

Thanks for the response.

The master cylinder is depressed.  I actually had to draw the cylinder onto the firewall since I couldn't get the push rod to install.

I'll remove the pusrod and shorten it.

The pedal rests against a brace.

Mike  

Let us know if your brakes still smoke after that.  

That took care of it.  Might improve my gas mileage too...  :>  

More mpg is always a plus when gas is over 3 bucks a gallon.