Alright, here's my story. The brakes on my truck started to get soft, then one pump to get pressure, then two pumps. Changed the master cylinder (myself) and the pattern started again in a few days. Took it to the garage, they said there was a crack in a front caliper. Okay, that was changed, new pads while we were at it, new master cylinder installed, a week later my foot hits the floor in heavy braking and it's been a one pump for pressure system since. The day the brake light came on I drove straight to the shop that did the work and told them to fix it. They said there were no leaks and didn't find any problem. They tried to push the blame off to drums, rotors, and rear brake shoes. Now, I may not be licenced, but I'm pretty sure that worn shoes and pads (that don't even make the telltale worn-out squeal) and aging drums/rotors will affect the pressure in the brake pedal. Am I on crack or are they? My bet is they are. It acts to me like they just didn't bleed the brake lines properly, since they weren't exactly firm even after they finished the job - but there was still plenty of travel left in the pedal. And if I remember correctly, worn rear brake shoes won't make THAT much difference in braking, since the front brakes do 80 to 90 percent of the actual brake work. Am I right here? Should I really tell these guys to shove their work up their collective @$$#$?? I know they really want to do a drum/rotor/shoe package for 4 or 500 bucks (with the 50 bucks in parts it takes), but I'm pretty sure having to pump my brakes has little to nothing to do with those parts. Sorry, I'm ranting. I've had the pedal pressure issue on cars before, a simple master cylinder change solved the problem on all those cases.

Chris Pollard
Dryden, ON
Don't mind me, I'm crazy.
:-X11

 

Since you've replaced master cylinders before, I'm sure you "bled" it before attaching the lines. If you havn't done it already, I would check the rear wheel cylinders, and maybe just go ahead and rebuild them. There is'nt all that much to the hydraulic brake system, and you're almost halfway through it now, might as well go the rest of the way.

 

What year truck? Reason being, the older, the easier, and somtimes cheaper too. I have heard of people getting bad master cylinders that were supposed to be new or rebuilt. Do you have power brakes? Your booster may be acting up too. I think you're on with your intuition...but it still points to the MC. Worn or not the pedal shouldn't have that much play...even in my old manual brakes. Drums are easy - they just require the right tools and know how, I think I priced mine to be about $100 for new drums, cylinders, and rebuild hardware...on a '79 F100. I think you should forever leave the place you went to (bad mouth them to everyone you know) and find another "reputable" shop for a second opinion before thinking of sinking $400+ into more brake work.

 

I agree. Worn brakes keep good pressure but you would have to push the pedal farther to create the pressure (the reverse is true when you put new pads and shoes on). So having to pump it up means you need to bleed them or you have another problem.

Don't mean to tell you what you already know but bleeding them is real easy(excuse me if you've done this.) Dump extra DOT 3 fluid in your master cylinder reservoir, loosen the banjo bolt on the caliper (you'll see fluid come out), put a plastic hose on it to catch the fluid, have someone pump the pedal down and hold it, tighten the bolt back up, have them do it again 2-3 x. Each time tighten the bolt while the pedal is down or air will re-enter. They'll feel the pressure build up and that's it. Throw the used fluid in your oil recycle jug (don't reuse.) Or you can buy a gizmo like I have the does a reverse flow and pushs the brake fluid up through the lines driving the air out.

A bad master cylinder, as I recall causes fading, the brakes tighten up good and then slack off or pulsate as presssure is applied. A bad booster requires alot more pressure by the foot to stop the vehicle. Bad fluid, mixed with water and crude, requires some pumping.
Whatever you do, check your fluid level, if you have a small leak and run low on fluid, it could be disasterous.

 

The truck's an 84. It's going back to them tomorrow to get whatever needs done to fix the problem. They said first time around it was a cracked caliper and replaced the one in question. The rear brakes (lines, etc) were re-done last spring, and they found no leaks anywhere in the system. It's not losing fluid or anything. I thought from the get-go that they just didn't bleed the bloody lines myself. I would have done it, but I can lay under the truck that long before my old whiplash/broken neck injury come back to haunt me. All I know is unless they find the real culprit and can show it to me, they're not getting another penny to re-do the work that should have been done right the first time. We'll see how it goes tomorrow.

Chris Pollard
Dryden, ON
Don't mind me, I'm crazy.
:-X11

 

I understand and I wish the best of luck. I also sympathize with the shops. During my schoold years in Hattiesburg, I worked at an Exxon station and did basic mechanicing, brakes, water pumps, fan belts, starters... The cars were always hot when you worked on them and sometimes, I'd try to save someone a buck by using an old part that I had to remove to get to another and then a week later it goes bad or the new part was defective and they come back and only know that the car isn't work right now and I was the one that did it. Not saying that's what's happening to you, but these old trucks just have alot of variables. Good luck, I hope it come out well for you.

 

I don't think worn out pads would cause a soft pedal. You have had some serious brake work done.I have scored the rotors with worn out pads, the rivets cut a nice gash, but the pedal was just fine. Did I read that you changed the Master cylinder twice? I would concentrate on your hydraulic system, something has been overlooked. Are you sure there isn't anything on any individual brake cylinder? Just a light dampening around the rubber boots would indicate a failure.If you have rubber lines going to the disc brakes, check them for dryrot.
I hope this isn't an incompetent garsge mech. Good luck

 

The first master was off my parts truck that had been sitting for god knows how long. I didn't expect it to make it much past pay day. It didn't make it much longer.

Happy to report that after taking it back they said "Yeah, I found some air in the back lines when I bled them. In other words, I don't think they even bothered to bleed them the first time after changing the master. I now have a good hard pedal with all of an inch or so of travel. It's nice knowing I can stop again.
--
Chris Pollard
Dryden, ON
Don't mind me, I'm crazy.
:-X11