Hello everyone, I am struggling with brake failure on my 68 with front disc, rear drum. I have had the Bendix booster rebuilt, rebuilt the proportioning valve, 3 master cylinders later (currently a Dorman, bench bleed), adjusted the rod, and have good fluid at all four corners and no fluid leaks and master bowl levels are maintaining level.
Here is the problem, with the car off pedal builds to a nice firm pedal, as soon as I start the car, I lose all pedal completely. When I pull the vacuum line off, the booster makes a nice swoosh sound and once capped, has pressure and the pedal returns somewhat, but not enough to drive. Basically, you can stop the car at idle if you pump it about 5 times. I had a buddy, recently retired after 40 years in the brake and alignment business, help me. He has checked all four corners and has eliminated any issues there, believes the proportioning valve is working properly, adjusted the rear drums, the rod to the master, etc. and he is stumped.
Everything was rebuilt less than 1000 miles ago and this all started because I was feeling something in the pedal and had the brakes professionally checked. They recommended I replace the front calipers. I did the calipers and the lines, and I now have this issue.
Anyone have a similar problem they solved or ideas on how to fix this?
Have you replaced the three flex brake lines?? When they get really old the lines will collapse resisting fluid to flow… Rear flex brake line is also known to get week and balloon up taking up all the brake fluid pressure… Just a couple of things to check…
Ive seen an issue with bench bleeding. The piston is pushed too far in & the seals get nicked by the bore Only push in about an inch or two. I use a screwdriver with a piece of tape marking the depth.
Thanks Nolen. I am replacing the rear line since I already replaced the fronts. I have good fluid flow to the back, but I’m replacing it either way. I appreciate the input regardless.
Thanks Bill. I did bench bleed it and its been properly adjusted. I have eliminated the master as the problem. I am leaning towards the proportioning valve or the booster, both of which have been rebuilt. I appreciate the input regardless.
Thanks Hemi. Working my way out to the calipers, but they aren’t on the wrong side. I did check that. I am starting to question if they are the correct ones for the car. I’ll keep you posted.