The Stovebolt Site Forums The Shop Area Driveline I need your help with my brakes on my 39 coe

ok I know you guys know brakes and I thought I did to being just 4 wheel cyls. and a master cyl. ok so here's what I have done, 4 new wheel cyls.(Jim carters) and a new master (Wagner from Jim carter) I got all new shoes and drums have been cut and adjusted, no hydro-vac,(never had one) I put in fluid and pump up brakes bled them from the drivers rear then to the pass rear and then go to the pass front and then drivers front.. and they work but seem to be soft. then I let the peddle rest for 5 seconds and the peddle goes to the floor, I don't have a pressure bleeder just the old foot and hold and the bled and close and the pump it up again until all the air is gone, I have done this until my foot hurts and it still goes to the floor, ok so what do you guys say is not right? my first guess is the master because the wheel cyl. are not leaking and the master is not leaking either. I have maybe a 1/8 of peddle movement before it engages with the master and I think that it needs 1/2 of play but I just want to let you guys know what I have here, thank you for you help! Dan

Hy baldybenny, did you bench bleed the master before installing it? In my 1941 maintenance manual it lists the sequence for bleeding as left rear, left front, right rear, right front, hope that helps.

Make sure you have the shoes adjusted pretty snug.

Thanks 3B,your help is always greatly appreciated ! I am going to remove the master and bench bleed it, its has to be that, and I will bleed the brakes as you listed!......... Don Thank you,I did adjust the shoes until contact and then backed off just a little, the front drums and shoes are NOS and the rears were turned with new shoes, there is one other thing that happens with the peddle pumped up and the top is off the master if I release the peddle slowly there's a gusher of fluid from the master. somebody was telling me that was air trapped any thoughts on that?

You can probably bleed the master cylinder without taking it off. I did my '53 a month ago. Take a short brake line and bend it so the end will go into the master and connect other to the out of the master. Top off fluid and pump the pedal slowly. It's way easier than doing it in the vise and then installing it with fluid running down your arm as you bolt it up.

Thank you Don! I will do just that since this ones not that easy to take out , Ya that fluid running down arms is such a wonderful thing to feel...lol Thank you.

Also, the instructions that came with my new MC, says when bleeding the MC, only use short, one inch strokes, do not pump all the way in. It had a plastic plug to put where the brake line goes, then slowly pump the plunger with one inch strokes, waiting 15 seconds between strokes. The air will come up in the MC in bubbles. Do this until no more bubbles and the plunger will only go in about 1/8 inch.
On mine it took several times doing this, until all the bubbles were gone. Took about 20 minutes total, including waiting the 15 seconds between strokes.
Oh, yeah, leave the filler cap off while bleeding.

Thank you old GMC gold, I did that today and here's what I found out, after bleeding the MC and all bubbles were gone I started to pump the brakes and I heard a blow out, looked under the truck and fluid was leaking, just under the harmonic balancer, I removed the line to see a ware spot that most likely was sucking air and leaking, there was fluid in the channel that was not leaking on the floor before but there was a pool there in the channel, I made a new line and installed it and then started over, I bled the wheel cyls.as 3B told me and I still didn't have the peddle that I wanted so I checked again the shoes as Don said and they were not that snug so I adjusted them again and like magic I had a peddle like new!.... the 39 COE has brakes! Thank all of you guys for all your help! I will be driving this truck out of my shop tomorrow if its not raining,,,I will try and get a video of it driving out, its been over 30 years or more since it has been driving! Saving another old truck feels great!!!! Dan

Hy baldybenny, great news, good luck with the weather tomorrow!