Brake pedal to the floor

[neilert]

Hello everyone- I really enjoy your site, this is my first post. I recently purchased a '58 BN4 100/6 with drum brakes. The brake pedal hits the floor, and the brakes still aren't fully on.

The first thing I tried after reading all of your similar posts is replacing the master cylinder, bench bled, then bled lines with a Motive pressure bleeder.

Then I noticed a small leak in a front wheel cylinder, so I replaced all 4 front wheel cylinders and brake pads, then bled the system again.

The brake lines and rubber lines look recently new, with no leaks. The rear cylinders and pads are new, and don't leak.

All 4 wheels have been adjusted until the drum can just turn without hitting the pad.

There is almost no resistance on the pedal, and it will finally brake if I pump 3 or 4 times. Then, the next time I pump it goes back to the floor. The new master feels exactly the same as the original master.

Any help would be appreciated!!! Thank you, Neil

 

[Cutlass]

Did you replace all of the old fluid? Other than that, seems like you've hit all the bases. Were the master and wheel cylinders new, with good seals?

 

[neilert]

Yes, I've bled the system several times, using 5 quarts of new fluid so far. The master and wheel cylinders were purchased new. Neil

 

[Ed_K]

Hi Neal,

Welcome to the forum.
Sounds like you may still have air in your system somewhere or perhaps a small leak in one of the lines or fittings is allowing air back in after you bled it. I would expect a puddle somewhere on your garage floor ? Is your fluid level going down after you exercise the pedal ? Perhaps you should loosen the line at one fitting at a time while someone else operates the pedal until you find where little or no brake fluid comes out when the pedal is pressed. That should help you narrow down the problem area.

Ed

 

[Cutlass]

The only other thing I can think of, other than Ed's comments, is the bleeding sequence. But given your obvious knowledge of the subject, I'll bet you've thought of that already.

 

[Ed_K]

I almost forgot something. If your brake system plumbing is similar to my BJ8, there is a connector with several pipes and a
small line that runs UPWARD to the brake light switch. If you trap air up there then the whole system has a built in air "sponge" until you bleed the air out right at the switch by cracking it loose with a wrench while someone is pushing down on the brake pedal, ( the same way you bleed the wheel cylinders). That may be your problem since you didn't say anything about any brake fluid leaking down on your garage floor.
Ed

 

[neilert]

I believe it has to be air in the system. I pressurized the master and lines with 20 pounds of fluid pressure with the motive bleeder and checked all of the lines and connections. They are dry.

There is a 3" section of tubing that travels upward at the master. The union for the switch and other lines rests by the base of the radiator on the frame. I suppose air could get caught in the union, but I have sent so much fluid through.....

 

[Ed_K]

It must be different than a bj8. Try cracking the line loose right at the master cylinder, bleed it, tighten it back and move to the next one on the line until you bleed it at every connection. There must be air trapped in there some where if it takes a few pumps of the pedal to apply the brakes all the way.
Working on any car builds up your skill. These cars build your character ! If it was easy, anyone could do it .
Ed

 

[neilert]

Thank you for your replies Ed. I have never had a problem bleeding brakes. The workshop manual says that pressure bleeders do not work well on this car. Do you think I should just use the friend pushing pedal method? thanks again, Neil

 

[Ed_K]

Thats what I would do. You want to know when and if you are letting out air. If you crack open a fitting, someone pushes down the pedal and no/little fluid comes out, you know that is the place where the air is trapped. Keep working it until a little fluid comes out without any bubbles/noise. Then move to the next one. If you are using a powered machine, you may not notice if there was air trapped in front of the fluid. But I suppose if you systematically bleed each connection with a machine, when you are finished, there shouldn't be any air trapped. Once you finish this process and if you still don't have solid pedal, then you should double check that your adjustments of all of the brakes are right. Perhaps on one or more wheels, all of the mechanical slop has not be taken out. Perhaps only one shoe is dragging, the other not close to touching, thus your pedal stroke has to take the slop out of the system before the full brake pressure can be applied.
One thing for certain, it will be the last thing you check !
Ed

 

[nevets]

On one of the posts someone suggested applying teflon tape to the threads of the bleed screw when using a pressurize bleeder, otherwise air will enter the system past the bleed screw threads during the bleeding operation. Thought it might be worth mentioning.

 

[neilert]

Fixed it! Thank you everyone for the support. Ed, I used your method of starting at the master and working my way down the line at each connection. The pressure bleeding with the Motive bleeder had no bubbles, but several aggressive pedal push bleeding strokes sent quite a bit of bubbles through. The pedal is rock solid now. Neil

 

[Ed Kaler]

First, I'm a different "Ed" Neil, right Ed?? :thumbsup:

Next, Congrats not only on the car but in "winning" your FIRST "battle"!!

Now, for all you folks 1 of Neil's probs in DOING the "job" is that the PSI he was using was about 2 times TO much!!!

I found out the HARD way when I started using EeziBleed a decade plus ago. :hammer:

EIGHT to TEN PSI MAX and all will be well!! :angel:

Neil, the ONE bit of info you did not mention (you "should" know from "A" days but...) is what fluid did you use??


Ed

 

[Ed_K]

Way to go !

:thumbsup: