88 Master Cylinder/Brake Question

[Regan]

I have been working and replacing my front LR pads, etc. I have also bleed the brakes for air. My brake pedal, on the 1st press, goes all the way to the floor, a second press on the brake holds and I have brakes.(This before and after pad/lining change). Calling around local brake companies state it sounds like the master cylinder or air in the lines. Any ideas? Again, no brakes 1st time and goes all the way to the floor? I need a fix so I can use, as it is no good at the moment.
Thanks, Regan

[Les Parker]

Have you tried blanking the rubber flex hoses off?
If there is still movement in the pedal/master cylinder, this would indicate the problem is in the master cyl.

[Mercedesrover]

Don't look for trouble you didn't have to begin with.

How were the brakes before you started?
What exactly did you change?

If you had good brakes before you started working on it and the brakes have this problem now, it must be something you did.

Did you replace the wheel cylinders? Maybe you just need to bleed it more.

Did you replace only the shoes? If so, and now you have a low pedal you probably only need to adjust the brake shoes. If the brake shoes are too far from the drum, it will take two pumps for your shoes to make contact.

I wouldn't suspect air in the master unless you replaced it or let it run dry.

[Regan]

I had poor brakes when I got the 88. I adjusted the shoes to get better brakes and then it got worse, in that littel or no brakes 1st press. I asked forum and ordered shoes for front and replaced(yesterday). Now, same thing, it takes two times to get pressure and stop, something I would like 1st time. I did not replace the wheel cylinders. In my work, I pressed the brakes with no drums on and the cylinder, front left, bleed out. I bleed the line, but maybe not enough. Suggestions, Regan

[Jeff Aronson]

I had poor brakes when I got the 88. I adjusted the shoes to get better brakes and then it got worse, in that littel or no brakes 1st press. I asked forum and ordered shoes for front and replaced(yesterday). Now, same thing, it takes two times to get pressure and stop, something I would like 1st time. I did not replace the wheel cylinders. In my work, I pressed the brakes with no drums on and the cylinder, front left, bleed out. I bleed the line, but maybe not enough. Suggestions, Regan

Regan,

I know this is frustrating, but you possibly have two problems.

First and foremost, when you start the car and push down on the brakes, you said the pedal goes down quite far with little brake action, and on the second pump, you get brakes. Is this right?

Now, try this again but on the second pump, push on the brakes hard. Does the pedal stay firm, or does it begin as firm and then slowly seep to the floor? If it is firm and holding on the second pump, it is unlikely that you have a master cylinder problem. More likely, you have an adjustment problem.

If the brakes do seep to the floor on that second pump, then you likely have a leak inside the master cylinder.

Assuming you don't have a leak, try the same test after taking a pair of brake hose clamp pliers - or a set of vise grips with lots of duct tape wrapped around the tips - and closing off the hose to the rear brakes. Is there any change? If the brakes improve in terms of pumping, then you likely have an adjustment problem in the rear brakes.

Once when visiting Rovers North, I replaced all the shoes on my II-A on their grounds and afterward, adjusted the brakes. They did not improve one whit in terms of pumping action. Frustrated, I asked Mark Letorney to come out and try the brakes. He took a few stabs at the pedal and told me to adjust them again. Of course, I felt he was wrong but I adjusted them again. Then I tried to hem and haw my way out of admitting that he was correct - I just had not adjusted them properly. So do try the adjustment process again.

Now for your second possible issue - remove the drum on wheel which you experienced the cylinder seals popping because there were no shoes installed when you stepped on the brakes. Is there any sign of leaking brake fluid? If so, then the seals on the wheel cylinder and leaking and need replacement. If not, then examine carefully the arrangement of your brake springs. Are you certain they match the photos and diagrams in the manual? If necessary, take a photo of that wheel and remove a rear one on the same side of the car to confirm that you replaced the springs correctly. You would not be the first to get these confused.

If all is well, then put the drum back on the wheel and loosen the bleeder screw on the wheel in question. Run a hose from the bleeder screw to a clean glass or jar. Let the fluid drip out; if you have a helper, then have them push down on the brake before you open the bleeder, and hold the pedal the to floor until you tighten the bleeder, and then release the brake. Check your fluid level and repeat this a few times. Often gravity alone will bleed the line. Leave your rear line clamped off and try the brakes again. Any improvement? If not, then adjust the brakes and do the opposite side on the front. See if your brakes improve.

If you're still experiencing problems, drop me a PM and I can suggest other steps.

Good luck!

Jeff