Need Brake Help on '51 Sedan

amodel25

Senior Member
On a 100 mile or so road trip Sunday (the hottest day of the year so far) I noticed that my brake pedal started getting gradually stiffer. I was on the highway and the water temp started going up and power dropped off. I pulled to the side of the road, pushed in the clutch and the car stopped itself. The brake pedal was hard and would not move at all. I got out and the brake lights were still on (pressure switch on the master cylinder). I crawled under and cracked the tube fitting at the master cylinder and got a spray of fluid for 2-3 seconds. Tightened the fitting and checked the pedal and everything seemed OK. The brakes worked OK the rest of the way home (about 10 miles). The brake system (single master cylinder, drum brakes) was rebuilt about 3 years ago with a new master cylinder. I've had the car 20 years and never had this problem before. Any ideas?
 
Adjust the rod that pushes the master cyl, should have 1/8" play. Also if you have not changed the 3 rubber hoses, change them now, they tare inside and fluid goes in and can not return.
 
Make sure brake shoes are releasing (including from parking brake mechanism). Make sure brake lines aren't too close to exhaust plumbing. Master cylinder has a return port that can clog. Flush new fluid through system and clean/rebuild master cylinder.
 
The bolt that goes through the m/c pushrod has a eccentric cam shoulder on it. losen then turn this untill the pushrod goes forward all the way,the clip that holds the spring should be facing foward in a straight line with the return spring.
 
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