I have been working on my wifes 49 dodge coronet for about 1.5 years now and all I have left to do is the brakes....But I am having MAJOR isssues! I have replaced the original master cylinder (which was 1 1/8 bore size single port- frame rail mounted) with a 1" bore dual port MC mounted on the firewall. I have bought all new wheel cylinders. I have ran all new brake lines and all new hoses. I have installed a new "under dash" swing style pedal. The dodge coronet has 6 wheel cylinders. 2 per front wheel each and 1 per back wheel each. Im not sure of the bore on these. I have bled the brakes 10,001 times and I still have a soft pedal that bottoms out on the floor before the wheel cylinders are fully actuated. I have put 10 lbs residual valves in the lines....no difference. I have checked and rechecked the complete system for leaks.....none. The MC stays full all the time. If you plug the front hole and just use the back one (or vise versa) I get a great solid feeling pedal. I purchased another MC 1 1/8 bore from Auto Zone and this did basically the same thing. What is wrong? I am at my wits end on this one!!!!! One side note....I used this exact same set up on my 50 ford and it has worked wonderfully for two years now. I have great brakes in that car, thus the reason I went with it again in her Dodge........HELPPPPPPPP! Thanks, Mike.
I would think when you block the front or rear of the MC you get a good pedal because you are hydraulically locking the MC. It sure sounds like air in the system, I hear you on the bleeding. Think I'd try and clamp off the flex hoses and see if the feel of the pedal immediately gets better, then open one at a time and see if it goes bad as soon as you do.
Adjust all shoes to a light drag and see what that does for you.That is a Lockheed design simular to 39-41 Ford in that it has adjustable anchors that need to be reset with new lining. Untill the anchors are set correctly you will have a problem with getting a good adjustment
Couple things I can think of right away: 1) you may need that 1 1/8" bore master, you are feeding 6 wheel cylinders vs the 4 of your Ford. 2) the firewall is not designed for mounting of the brake, so may be flexing a bit more than you suspect. I ran 1" angle from cowl to toe board on mine and vastly improved the rigidity and thus the pedal feel. 3) modern shoes can have an improper arc, pull the drums and check the shoes' arc against the drum. Thats all I can think of for now. Cosmo
Just a shot but seems to me it's that 2 cyl. per wheel giving the problem. Air just travelling from on cyl to cyl instead of out the bleeder. Have you tried a power bleeder? I'm having problems bleeding the vette calpers on my rpu. 3 bleeders per caliper. Nitemare.
Thanks guys for all the suggestions! Most of them I have already tried, but my buddy is gonna "borrow" a pressure bleeder this weekend from work and we are gonna see what happens! What a great site with a network of people who do their best to help each other! I love it! Mike.
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