86 T4R V8

Added a Lexus dual diaphragm brake booster and MC 1 1/16 bore to my T4R. Also added a 10lbs Wilwood residual valve to rear drums & 2lbs Wilwood residual valve to front. Also upgrade V6 calipers and rotors. I still continue to get soft pedal. I have to pump it a few times to get where I like it. What am I doing wrong? Is it because this MC was made for ABS and rear disc brakes? Or is this MC is too big for my application? I was on a budget so I had to use what I got, that’s why I used the Lexus setup to possibly stop this V8.

 

Could be the bigger MC. I was reading another thread on here a few days ago and the guy was having a heck of a time balancing his brake system. He ended up going back to stock MC. I dont know how abs affects the setup.

 

Soft pedal or long travel??

Soft pedal your drawing in air someplace all those new connections

could be just a speck of dirt in any of the connections bad bleeder valve

it can draw air and not leak fluid

.Rubber hoses swelling under pressure if they were not replaced.

Rear shoes adjusted up correct ??

You did go with new rotors new drums??

New Pads and shoes??

The brake booster and Master Cylinder just move fluid they have no idea there is a ABS computer down stream.

 

Bench bleed the master?
What not an adjustable proportioning valve?

 

Brakes should be hard with a crazy big MC like that. Keep on bleeding it till you just can't stand it, and you might get that last air bubble out.

 

OH, along the lines of bleeding... I recently had to bleed my brakes. I was SO frustrated at some point, I bled and bled like I have before, and no more air was coming out. But the brakes were practically not working. Angry and about to shoot the damn brake system, I started the car and asked my helper (wife) to push on the brakes hard... To my delight, with the booster and all, that sucker made some music and a whole bunch of air came shooting out. Both of the rears and proportioning valve body. That was a relief. I suppose what happened was the air was trapped in the system until a good boost was applied to blow it out...? Try that perhaps. It's easy, and free.