brake bleeding tips.

[38tech]

I believe on the 1940 Plymouth, on the back of each wheel cylinder, there is a brass adapter that the brake line threads into and the adapter itself is attached to the wheel cylinder with a bolt that requires grooved copper washers .
I experienced the same problem you are having. We checked & replaced every part except the  adapters.
By accident, I discovered the right rear adapter, due to over tightening, had a hairline crack in it, causing me to have brakes one minute, and then no brakes less than 2 minutes later.
What baffled me was, that under pressure, the brake fluid didn't seep out of the crack.
I would check every adapter for cracks and check to see if the copper washers are installed correctly.
John

[John Hendricks]

If u are bleeding the system manually--someone sitting in the seat working the pedal and someone with a wrench on the floor--don't push the pedal all the way to the floor.  Put a chunk of 4x4 next to the pedal so it won't go all the way down.  It says in the manual not to push it more than half way but it is easy to gloss over that.  I had a similar problem with air appearing in the system.  When the pedal goes half way to the floor the  motion of the pedal shaft is fore and aft at the master cylinder.  When u push it all the way to the floor, that fore and aft motion changes to up and down on the shaft into the MC, tipping it just a bit and letting in a bubble of air.  when i quit pushing the pedal to the floor the air went away

[blueskies]

I used a pressure bleeder on my '50 Plymouth brakes.  I just bled them again last night, and finally have the air out.  It's a one man job with the pressure bleeder, and you can pressurize the system and let it sit for a while, and see if it is leaking down.  If it is losing pressure over time, there's a leak somewhere.  You can buy a pressure bleeder like mine on the net for about $40, or you can make one from a garden sprayer for about $15.  You will need to have an extra master cylinder cap to attach the hose to.

If it's not air in your system, I would suspect your master cylinder.  Also, when you are bleeding the system, you should turn the minor shoe adjusting cams so that the shoes are all the way away from the drums, to help get the air out of the cylinders.

Pete

[40mopar]

I'm new to this board and have found some very valuable information to assist me in fixing up my 1940 business coupe. ;D I'm stuck on the brakes right now and need a few tips to completely diagnose the system.

I've bled the brakes maybe 10 or more times. I can typically get a good pedal and think everything is good...only to come back in a couple of hours and have the pedal go straight to the floor.  after a handful of pumps it will get good again.  I have changed every brake line, bought a new master cylinder, bench bled the master cylinder, inspected and rebuilt the wheel cylinders. I've put in steel braided front flex lines (from parts from Godman Performance) and replaced the rear flex lines.  The only parts that I have not yet replaced as far as the braking system are the brake switch, and the little T that sits on the rear end. I'd like to find these just to replace them since everything else is new.   

I am at a loss.  ??? The rest of the car is mechanically ready to roll just some glass and body work to get it going. I really want to drive this thing this summer. Any ideas.