can't get the brakes right...

I have a 1949 dodge coronet with drum brakes all the way around. I have installed a 350 in her and have a vaccum booster and master cylinder on the firewall. I can't seem to get the brakes to bleed. To get the car to move on it's own, I wanted to just run the front brakes. I have new wheel cylinders installed and everything is tight. Does it matter which port - back (primary) or front secondary) that I have the lines hooked into? Also, should I run the engine while I'm bleeding the brakes? I have the vaccum booster tubed into the carb.

 

If they are the stock drums, check out threads over on the P15-D24 forum. Those brakes are tricky to adjust, they require a special tool (which you can make yourself with PVC pipe and some sort of indicator) that measures brake pad distance from center of hub, and keeps that distance constant for both edges of both pads.

Chrysler didn't license the Bendix self-adjusting patent and thus MoPar brake adjustment is weird.

 

is any fluid coming out at all ? i usually gravity bleed newer setups before pumping the pedal by opening the bleeders till fluid starts dribbling out.

 

Is the master cylinder disc/drum or drum/drum unit? Does it have one reservoir chamber larger than the other? If so, the larger is intended for the front brakes. If it is a disc/drum unit, it likely does not have a Residual Pressure Valve internally, and you should have a 10 psi RPV in the line between the wheel cyl and master.

Did you bench bleed the master before installing it? If not, you can do that by installing a short line from the outlet port of the master looped back into the reservoir and pump the master slowly until the fluid is free of air bubbles.

Also, most Mopars front brakes of that era have two wheel cylinders. I think you should bleed the one furthest from the hose inlet, which is probably the lower WC, and then the upper one. Also, make sure the sjoes are adjusted properly.

Hope this helps.

Ray

 

on a two port system the one the to the rear(plunger goes thu first) should go to the front wheel .. you may have to much pressure to the w/ cyliders now... new m/c old style w/c ..
you may need a in line valve ?
manually adjust the drums so they spin freely while elevated may just barely rub as they spin is ok
shoes on correctly longer one towards front of car?
.. also a new(different) m/c has to have the proper leverage/angle when hooked to the pedal .. enough travel and stroke
many other things to check but start here

 

Before you get carried away with this you need to know that the mopars of your vintage used anywhere between 1-3/16 to 1-5/16 inch bore master cylinders because of the volume required to fill 6 wheel cylinders, so if your trying to make this work with an 1-1/8 bore m/c cylinder I can tell you that's never going to happen. In addition, they ran 8.25 to 1 pedal ratios to get enough pressure out of a bore size that large to make the brakes work, so chances of you getting enough pressure with your current booster /pedal assy. even with a 1-1/4 bore dual m/cyl. are probably pretty slim.

 

ECIGUY is worth paying attention to...they helped me set-up my sedan with the four wheel discs. I had some real mis-match problems they helped solve.

 

Well, after disassembling everything frome the wheels back to the booster, I think I've found the culprit(s). I was using 2 front brake hoses from the old build I had been doing and they must have set up with condensation and gunk inside of them and they wont push any fluid through. I can't even get my compressed air (at 145 psi) to go through. Soaked them in brake cleaner and tried again without luck. Called my favorite parts store Oreilly's and they hooked me up with 2 from the wharehouse to be delievered in 2 days. I'm really hoping to be able to get the brake bled on Saturday so that I get her to move in and out of the building on her own power. Then once I get the brakes right, I'm going to turn lt hand circles for a while, then turn right hand circles for a while to hopefully break loose or heat up the rear axles enough to get the drums orr to fix those brakes.