The Stovebolt Site Forums The Shop Area Driveline Need brake help

HI everyone. I just completed a complete brake job on my 1949 1/2 ton Chevy pickup. It has the huck style brakes on the front and bendix brakes from a Dana 44 rearend on the back. The overhaul came about because the left front wheel cylinder went bad and blew out brake fluid and I had no brake pedal. I put all new wheel cylinders, brake shoes, and hardware all the way around. The master cylinder is about a year old, so I didn't change it out.

I also updated the hub bearings on the front, changing out the old ball bearings for tapered bearings with new races and seals. I got it all back together and I can't get pedal to stay. I've tried flushing and bleeding with the one man style with air compressor. I've tried bleeding the old fashion way with one person pumping and holding the brakes and bleeding that way. I've bled them at least four times and I still cannot get pedal to stay.

It takes 15 to 20 pumps to get pedal. As long as you hold the brakes, the pedal will not go down. If you let off the pedal for any amount of time, it goes to the floor the next time you hit the brakes. I've checked for leaks and can't find any. I have fluid coming out at all four wheel cylinders. With the cap off the master cylinder, it will shoot fluid out of the top opening when you press the brakes. I don't know what else to do except take it to someone who knows how to work on brakes. Any suggestions?

The system is introducing air from somewhere. Rebuild or replace the master cylinder.

Did you replace the steel and rubber lines?

Are all of your connections tight?

Mike B

If all tight and dry, master cylinder, as previously stated, is your next avenue.

I did not replace the steel lines. They looked to be in pretty good shape. I did replace all the rubber hoses, fittings, and washers. Everything is tight with no leaks. I didn't suspect the master cylinder because I just put a new one on last year. I've got another one ordered. We'll see if that fixes it. Thanks everyone. I'll update once I get the new master cylinder put in and everything buttoned back up.

Naturally, when I disconnect the brake line from the master cylinder, brake fluid will run out from the master cylinder and from the steel line. When I install the new master cylinder and reconnect the steel brake line and refill with brake fluid, I'm assuming there will be air at the beginning of the system. Is there special procedure for bleeding in that circumstance to get that air from the front of the system or do I just need to bleed the brakes again like normal at all four wheels?

Be sure to bench bleed the master cylinder. Instructions should be in the box.🛠

You probably don't have the shoes adjusted correctly. There are 2 adjustments on each wheel on the Huck brakes. They are all right hand threads. Adjust each one till you get a heavy drag. Then back it off about 4 notches. The same with the Bendix brakes one adjustment. You will still have a small drag but they will seat in & be OK. If after you get a good pedal you can back the adjustments off a little if it bothers you.

George

And use this at the cylinders.

I'm pretty sure I have the shoes adjusted properly. There is a slight drag at each wheel.

I have been using that very brake fluid bleeder from Harbor Freight.

Sorry, I went back and re read your first post. You did say that.

YOU MUST bench bleed the master BEFORE install as several have said. Glad you are getting a new one. That will probably fix the issue. Those instructions come with every unit as well as the bench bleed hoses. Follow them exactly. Then install and bleed the system.

if you kept the old MC, they are real easy to rebuild. Yours, being fairly new, just had Chinese rubber seal failure. Kits are cheap.
You may want to study up on silicone brake fluid if you intend to use it. There is much discussion on that. None of it addresses whether unknown Chinese rubber compound can take it or not. Whether it's actually better for unknown Chinese rubber compound or not. If upon taking the old one apart you see the rubber seems "OK" but there is a black fluid coming off of them, it's the brake fluid eating them. Dissolving them. The reason we have trouble from parts we buy for our trucks is that it's all Chinese. The bad batch syndrome happens more often now-a-days. Therefore it looks like a bad vendor. They all buy from the same Chinese broker, So it's not their fault. They can't "switch" to another source. China is improving quality like Japan did. Aftermarket restoration parts are low on the Totem pole. So we live with it and change it out when it goes bad if we can't fix it. Whatever it is.