1972 duster 360 904 8 3/4 391

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scott hoffman

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Hi Scott here, I need some help my friend and I just completed a front drum to disk break conversion. The hole kit including all the break lines and the master cylinder. We even changed the rear from the small bolt pattern to the larger bolt pattern and larger Drum breaks, including new axles. The problem I am having is the breaks are mushy. The pedal goes to the floor two time before gaining any breaking power. The only thing I did not change is the proportioning valve. Nothing is leaking what could I be missing? Thanks Scott USN Retired.
 
Hey welcome aboard. I moved your thread to the brakes forum.

Did you bench bleed the MC before install?

Are your rear brakes adjusted up as they should be?

Do you have the calipers installed with the bleed down ?

Manual or power?
 
Hi the breaks are manual, yes on the bench test, the bleed valves are down but I do have the calipers installed inboard instead of the usual outer location not sure if that matters?
 
This car is a father sun project for my 11 year old he loves turning wrenches, and his brother has a 1973 340 roadrunner that was a earlier father son project and he felt left out hence the 360 duster.
 
ok taking a better look I see that the bleeder valves are facing up, the only part that is not new is the proportioning valve form when the car was four way drum brakes.
 
sound sto me like there is still air in there.. how are you bleeding the brakes?

i would try gravity bleeding them starting from the right rear, then the left rear then the right front then left front and see if it helps..
 
You will need a proportioning valve installed for disc brakes. I'm not clear from reading your posts whether you added one or not.....
 
Hi the proportioning valve for disk brakes is the only part that is not completely new to include all the brake lines that are also new, I am getting that I need to change that also? Thanks Scott
 
Yep the valve is different for discs. That said I've used a drum one with discs before temporarily, it worked... would not cause soft pedal like you are describing.
Keep on bleeding !
 
Ok so I am still bleeding the breaks like 7 times now and am going to get the new proportioning valve get it in and see if that helps, The pedal goes to the floor two times then it will brake.
 
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