[dpoltzer]

Still cant get brakes to work well. Have an entirely new (and I mean everything) 71 and up system in my 1970 FB. The GM shop Manual says you need tool # J-23709 to bleed the Disc Brakes. Someone on E-bay sells an equivalent tool for $135 but the crummy picture makes it look like a $5 tool. Essentially a piece of metal with a groove in it. The tool slides behind the head of the Combination Valves "proportioning/metering pin" . This tool holds that "pin" in, while you bleed the breaks. This is the only other function that I need to try in order to get my brakes to bleed out properly. Anyone tried bleeding their brakes using this type of tool and is there a way to fabricate this tool my self? I did try jabbing the brake pedal in while both rear bleeders were open attempting to re-center the pin but that did not help. Not sure what else to try. Thanks.

[Scarebird]

http://www.harborfreight.com/brake-f...der-92924.html

[dpoltzer]

Fabricated my own tool for free and it worked well to hold the pin in while bleeding the rear and front brakes again. Result: Brakes still no good. The pedal is plenty firm with the engine off but it gets soft and spongy when running. Still feels like the front brakes just are not working but around 25%

Even though I bled the system yesterday until there was no air present. There was again plenty of air at each of the four bleeder screws today. There are no fluid leaks and again, every line, hose,wheel cylinder, caliper etc. etc. is new. I don't know if air is getting in some how or if I was never able to get it all out. This is really getting me frustrated!!

[NEW64OWNER]

Sounds like you're trying to bleed by manually pushing the pedal with your leg. Get a power bleeder, there's tons of air in the system when you replace every thing and you'll be there forever with the old pushing by leg method.

[FrankieT/A]

Originally Posted by dpoltzer

I did try jabbing the brake pedal in while both rear bleeders were open attempting to re-center the pin but that did not help. Not sure what else to try. Thanks.

This trick only works with the plastic sender removed from the proportioning valve...
A power bleeder works wonders. Also, if you are using the leg method...1. Pump the pedal gently, no fast or sudden moves, that airates the fluid. 2. Have whomever is closing off the bleeders close them just before the pedal gets to the very end, just before the pedal hits bottom. 3. Five GENTLE SMOOTH pumps in between bleeds, then open bleeder. 4. Start at right rear, then left rear, right front and finally left front. One last thing, if you replaced frt calipers, it's difficult sometimes to get the new copper washers to seal. Often times you are better off using the old ones(washers).
If you already know most of this or all of this please disregard. Not trying to insult anyone.

[Murf]

I've got to add a vote for the power bleeder. I used one for the first time, recently. Wow, just Wow!
Beg, borrow or buy one. You will be impressed.

Good luck!
Murf

Sent from my Z936L using Tapatalk

[PontGuy]

Where did you get your brake parts? I went through huge bleeding problems when I replaced everything on my 69 seven years ago and bad parts were the cause of all my problems.

The first thing I found was that the intermediate rod between the booster and the master was too long and did not allow the master cylinder to return all the way. Resolving that didn't fix the bleeding problem though.

The big problem was with the new rear wheel cylinders. They did not leak any fluid but evidently they allowed air to be pulled back into the system through the seals when the brake pedal was released. When I finally tried replacing those wheel cylinders it took maybe two minutes to bleed the system using the old "pump the brakes" method. And the brakes have worked perfectly since.

[FrankieT/A]

Originally Posted by PontGuy

Where did you get your brake parts? I went through huge bleeding problems when I replaced everything on my 69 seven years ago and bad parts were the cause of all my problems.

The first thing I found was that the intermediate rod between the booster and the master was too long and did not allow the master cylinder to return all the way. Resolving that didn't fix the bleeding problem though.

The big problem was with the new rear wheel cylinders. They did not leak any fluid but evidently they allowed air to be pulled back into the system through the seals when the brake pedal was released. When I finally tried replacing those wheel cylinders it took maybe two minutes to bleed the system using the old "pump the brakes" method. And the brakes have worked perfectly since.

Yup, I have run into that myself. I have also run into master cylinders with an internal bypass leak...

[george kujanski]

Don't know about others, but I never have any problems doing a normal bleed without using the mentioned tool. Used the "wife pumping the pedal" method and also gravity bleed when working on one wheel only. Both methods successful.

I really should get a power bleeder tho.

george

[PontGuy]

Here is a thread that covered my brake bleeding issues. I wasn't the only one fighting the same problem and it took 70 posts before we finally identified the wheel cylinders as the cause.

http://forums.maxperformanceinc.com/...=598515&page=2

Don't know about others, but I never have any problems doing a normal bleed without using the mentioned tool. Used the "wife pumping the pedal" method and also gravity bleed when working on one wheel only. Both methods successful.

Yup, if the "wife pumping the pedal" method doesn't work then my take is that there is a problem somewhere in the system. And I never even heard of a centering tool until a few years ago and never had a problem bleeding brakes without it back in the day.

[Blued and Painted]

The proportion block switch provides the ground for the warning light. It does not block fluid if pushed either direction. It will self center once brake pressure is equalized.

If working by yourself, jam a long pry-bar between seat frame and brake peddle for a short brake pedal stroke. Adjust seat for tension.

[dpoltzer]

Thanks for all the great input Gents. I am actually on the 3rd set of new (not rebuilt) wheel cylinders and they are dry so I have ruled them out. Blued&Painted; The "pin" that I am referring to is located on the side of the combination valve under that small rubber cap. I believe it is called the proportioning valve metering pin. Not the post that the electrical wire goes to but thanks. I have called 3 local shops here in town and none of them have the pressure system that will fit on these old cars. I guess I will have to make my own using and old M/C cover or else see what is on the Market that will actually work. I have used my venturi bleeding system operating from my air compressor but no success. I will tackle this again this weekend and I will provide an update. Thanks again!!

[Scarebird]

ugh.

use the harbor freight vacuum setup. if you take an old bleed screw and drill it out as shown, remove the "real" one, bleed with modded screw, then replace the real one.

Using this setup you will not have to pump bleed again.

[PontGuy]

Originally Posted by dpoltzer

I am actually on the 3rd set of new (not rebuilt) wheel cylinders and they are dry so I have ruled them out.

Just to be clear to anyone reading this thread, wheel cylinders being dry does not mean that they are OK. Without a residual valve the brake system relies on internal seals in the cylinders to prevent air from being drawn back into the line when the brake pedal is released. This function did not work for either of my "new" cylinders even though they were perfectly dry. I swapped them for wheel cylinders with a different design and that immediately solved my problem.

[vidguy]

Originally Posted by Scarebird

ugh.

use the harbor freight vacuum setup. if you take an old bleed screw and drill it out as shown, remove the "real" one, bleed with modded screw, then replace the real one.

Using this setup you will not have to pump bleed again.

I went and bought one of these the other day because of this thread. Once I took everything out and started to set it up I realized that the three legged screw adapters are meant to be snapped into modern round master cylinders. The bottle adapters don't fit our master cylinders.

I cobbled together a flat piece of plastic, drilled some holes and screwed the fitting into the plastic. I'll sit this on top of the master cylinder and clamp it with the clamp springs that hold the cover on. The bottle tip needs to be in the fluid to keep it from over filling.

I haven't done this yet... but I'm curious how you used this tool Scarebird?
Did you just manually keep the MC filled and ignored the Fill Bottle?

[Scarebird]

Originally Posted by vidguy

... but I'm curious how you used this tool Scarebird?
Did you just manually keep the MC filled and ignored the Fill Bottle?

Yes. I noted how the refill bottle was constructed and tossed it.