[robinhood150]

My friend has a 84 truck with a d44 in the front and a toyota/d60 hybrid in the rear and 38" tires. The rear brakes are the same as the drums found in ifs trucks. The engine is a chevy 350.

We've installed a 1 1/4 chevy master cylinder and a wilwood proportioning valve per ErikB's writeup and numerous threads here. The booster is the stock toyota one. We can't get the tires to lock up, not enough stopping power. The brake pedal feel is good (maybe it's a little stiff? I don't know, hard to say).

Two concerns:
1. There may or may not be a small leak in the lines, just as we were finishing up working on the truck we found some damp connections. If there is a leak, it's not even enough to make the pedal fall to the floor.

2. We were unable to adjust the booster push rod thing, the adjustment nut was frozen. The rod contacts the MC, but barely...maybe 1/16th of an inch.

Will either of these two things prevent the brakes from locking up or is it time to upgrade the brake booster to a dual diaphragm?

Most of the things I've found from searching were about toy calipers, rear discs, or bleeding problems.

 

[robinhood150]

btt

 

[robinhood150]

That's my thought too. I just couldn't find any info to back it up.

 

[robinhood150]

My friend is under the impression that a dual diaphragm will only help with pedal feel (make it softer) and won't help with power. I disagree.

A dual diaphragm will give more braking power than single diaphragm, correct? It has more surface area than a single and would therefore apply more braking force?