brake problem!

I did a disc from drum conversion on my 69 rr,the basic swap 76 a body spindles ,new rotors,calipers,master. The brakes never seemed right,I've tried different bore masters without any changes So the other day I put a pressure gage on it and only got 500lbs of pressure. These are power brakes I used the booster that I had with the drums,the only thing I didn't change was the distubution block. I have a electric vac pump'so plenty of vac,pedel isn't hard,car just doesn't want to stop and no pressure to front. Any thoughts??? THANKS EDDIE B

Get the proportioning valve. distribution block, for a disc brake car. They are very different as pressures front to rear are critical in stopping.

Been a lot of parts consolidation in the caiper arena over the last few years. When I converted my 65 Cuda over I had soft brakes, mine are manual. Turns out the calipers were not on the right sides and was trapping air in the top of the bores. Might be your problem.

is it possible that you need to change the length(clearance) of the adjustable pushrod between the booster & the MC OR use a disc booster. FYI '76 A body calipers use a 2.75" bore as opposed to a 2.60" bore dia in the 73-75 calipers though as said w only 500 psi the calipers aren't the problem right now.

There are several items:
1. Is the master you are using for a disc/drum? if you are using drum/drum master you need to remove residual valve in the master front line.
2. Check your rubber lines. clamp them off by the steel line with vise grips and check pedal (possible line expanding)
3. Make sure the calipers are on the right sides ( the bleeder screws should be on top )
4. The drum brake power boosters in some cases is not strong enough use a dual diaphram booster.

more info: does the pedal go to the floor? is it mushy? does it stop and them bleed down?

let us know good luck

with several MC's it isn't that & a fresh conversion means the calipers most likely are good & the drum splitter means each corner has 500 psi that only leaves; Is the "linkage" not pushing in the MC piston in far enough(too much free play) or the drum booster is not pushing the "linkage" far enough into the MC even with the free play being correct.

The master is a disc/drum one. The brake lines are stainless line all new. The only thing I can think it would be is booster or disturubtion block. Also calipers are on rights sides ,bleeder to the top. THANKS keep the thoughts coming. EDDIE B

I'd bet on the booster not providing enough master cylinder travel. Only air in the system, internal master cylinder leakage, or not enough pedal travel would cause low pressure.

My car has a drum distribution block (70 Duster) with the 74 Duster spindles and 80 volare calipers and my brakes work great.

Instead of the distribution block you should use a proportioning valve or an adjustable proportioning valve for the rears.

I have a 66 charger with swap had the same problem it would stop the car but it would not hold the car back if i tried to brake torque put on a new dual diaphram booster from murrays for 108.00 worked great but i did have a proportiong valve. had to rework the lines a little cause the dual diaphram booster is longer. Whats the bore size of the master?

split the MC/booster & decrease the clearance via the threaded rod & see if that helps the situation. Dont go too far because if the piston assy in the MC is too far forward it'll cover the small vertical fill hole from the reservoir down to the bore but you might adj it & if it helps...