Why can't I get good brakes on this old pontiac?

J

Johnny

New member
1978 bonneville has had brake problems since I bought it. The brake pedal has always been really soft. First the rear brakes would grab alot, replaced rear shoes and no longer have that problem. Then, developed a leak on one of the rear brake lines, so I replaced the line and no longer have that problem. All the while, the pedal is still very soft, so today I replaced the master cylinder and bled thoroughly at each wheel. Pedal then felt alot better, but then a wheel cylinder sprung a leak, so i replaced that, then bled some more. Now, the pedal feels better than ever part of the time, and then all of a sudden it will go all the way to the floor, worse than ever, and I have hardly any brakes at all, If I let up on the pedal for a second and then try it again, it goes back to being alot better, and does about like it should. Then a mile down the road, it goes totally soft again. I can't figure out what to try next.
 
do you have add fluid between repairs ? how much have cut brake drums ? have you replaced master cyl ? when you adj brakes can you lock up and release with star wheel ? engine idle smooth ? 1st check power boster for brake fluid go under dash look for fluid running down inside 2nd make shure master cyl not leaking internall easyer to replace with new or good rebuilt if drums cut to much they will expand with heat and hard use so check with gauge inside measurement you may need go to old time machine shop for that one if your car has ballance valve in lines under master cyl check if it works by gently loosen line from fron or back one at a time with some one gently pushing on pedal tighten line before releaseing pedal and pedal going yto floor if you need more email me
 
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