Help with hard brake pedal problem

[Aard88]

I have an early '65 (some call it a 1964 1/2) It stops great. After driving a bit with some stops the brake pedal gets very hard. When I stop (foot off the pedal) the brake lights stay lit. This car has the single reservoir MC with the brake light pressure switch on the MC. Manual brakes with drum brakes all the way around.

I have ordered a new switch just in case it is sticking, but I get the feeling that is not the problem. Something is not letting the pressure dissipate (fluid return to the reservoir)? Also after about 20 - 30 minutes the pedal goes back to normal, like the pressure has been released. Does anyone have any ideas on this problem? Thanks in advance.

 

[TOM B]

Sounds to me like one or more of the disc brake pistons is rusty or corroded/
When cold and the brakes applied the pistons will push out good but will hang in the out position, not enough to drag the brakes though,/ This will give you the hard brake pedal feeling, then when the pistons and brakes get a little wormed up then they will release the whole way and the pedal will go back to normal.

 

[rbohm]

you say the pedal gets real hard when the brakes warm up, but does it still stop effectively? or are stopping distances longer?

 

[Aard88]

It stops fine when the pedal gets hard, it just never returns until after it sits for a bit. As to the response that it is the Caliper pistons sticking well these are drum brakes there are no calipers at all. The fronts have been replaced recently. The Previous Owner did a brake job on the front.

 

[HookandLadder]

If you pull up on the brake does the light go out? Could be the linkage hanging and needs new bushings or the Master could be sticking.

 

[rbohm]

check the bushings in the pedal support as if they wear they will allow the pedal to contact the steering column causing the very problem you have. also when the brake lights are on, crack the brake line at the master cylinder and see if the pressure releases, if it does then consider replacing the master cylinder, best with one from a 67 mustang and plumb the system for a dual master cylinder.

 

[Aard88]

Yeah I think it's the Master Cylinder sticking. In fact...I drove it today and it was fine, after 4 or 5 stops the pedal got hard again. So I used some kinetic engineering, I made 3 or 4 hard stops. Voila problem solved. Pedal when back to normal. This car has sat for awhile. So I think the piston in the MC was sticking, I think using it (abusing it?) freed it up. I'm going to put power brakes on the car soon with a new Master Cylinder so that, hopefully, will totally remedy the problem. Thank you all for your help!

 

[coogs]

If it's got drums all around, thats normal. 60's cars had lousy brakes.
Once they get hot they no more work to good.