I have a 64 Fairlane that Installed a dual master cylinder (67 mustang) in place of the single cylinder for safety.  The drums and wheel cylinders are stock on the front and the rears are off a 1969 Fairlane with larger drums.  I installed a line lock from Summit Racing (Hurst product).  I can't get the line lock to hold the front wheels firmly.  The original master cylinder was a 1" diameter and the new one is 7/8', based on what I have read I should have more pressure.  The brake pedal is extremly firm, the drums and shoes are brand new.  I have tried adding a residual valve, thinking the master cylinder did not have one and also installed a proportioning valve.  No matter what I do, I can't get the front brakes to hold firmly.  I am using the line lock solenoid as the T-fitting to the respective left and right front brakes and have tried 3 different master cylinders without any luck.  The only way that I can get the line lock to hold a little bit is by holding the pedal down, engaging the line lock release the brake pedal and push it down again and relase the line lock and then engage it again. 

What am I missing here?  When I take of the drums, you can see segments in the lining where the brake has tried to grab the drum.

I will eventually switch to disc brakes, but this setup should work fine for now.  Everything is new!

Any break experts out there that can help with this one??

Your help would be greatly appreciated!!!

Greg

What's throwing me off is that they're front drums and not discs.  I think once you convert them to disc, this problem will go away.  But right now I have to ask are they fully adjusted?  They may not be clamping as much as they should because I've seen that before.  Especially since they're on the front where about 70% of your braking comes from, you might need to readjust the shoes.  It just sounds like the shoes aren't grabbing enough and allowing it to roll.   

Hello,

I can't figure it out either, they should hold without any problem.  I have adjusted them up and that doesn't seem to help.

Is the long shoe supposed to be in the front, or the back?

Greg

I think it's supposed to be in the back.  And if they're adjusted right, then the only thing I can think of would be the solonoid and it allowing the pressure to bleed off.  Maybe you might want to check that out...