F350Dually

just did the 5 lug swap and other stuff blah blah blah and after getting everything done the brakes are very soft and the car seemes to slow just the same as it did when it had drums can anyone help me?

mjr46

did you bleed all the air out of the system??

F350Dually

yup twice over did it the first time by my self then with a friend and both time there was no air

USMC1775

What condition is the booster in? Check the lines for wear, check for leaks around the booster unit

Derf00

Some vehicles require a different Master cylinder for disc vs disc + drum or drum + drum.

Is this a dually or a car? Also, is the proportioning valve internal or external to the master cylinder? If you have a brass block that lines from MC go into before going to the rest of the vehicle then it's external. This part is typcialy different depending on the brake setup because the amount of hydraulic pressure needed to "activate" drums is much lower than that required to activate disc, thus the soft feel. The rears are not getting fully activated.

Stopping power on disc + drum is usually 80%/20% with disc+disc being 70%/30%

FivePointOhh

i slightly remember your previous thread. did you do the 4-2 port conversion or 3-2 port conversion?

was it v6, gt or cobra booster? do you know which year?

F350Dually

sorry its an 88 gt, i did the 3-2 port conversion with a brand new mc from a 95 5.0, and am using a willwood adjustable valve with the factory one removed.

F350Dually

and it has the stock booster, if i need to change the booster i may just go over to a manual conversion

FivePointOhh

the booster needs to be different from all the write ups i've seen. your booster is set up for disk front and drum rear. you need one set up for disk front and rear.

F350Dually

well i can say that when i unplugged the booster from the vac the pedal feel didnt change