Pirate 4x4 banner

1 - 13 of 13 Posts

·
Registered
Joined
·
853 Posts
Discussion Starter #1 (Edited)
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.
 

·
Registered
Joined
·
853 Posts
Discussion Starter #4
That's my thought too. I just couldn't find any info to back it up.
 

·
Registered
Joined
·
9,385 Posts
And if you're going to replace the booster, you might as well get the dual-diaphragm one, especially since you've got a heavy V8.

Good luck, keep us posted.
 

·
Registered
Joined
·
853 Posts
Discussion Starter #6
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?
 

·
Registered
Joined
·
16 Posts
If I get a new brake booster it will definitely be a dual-diaphragm. I know the late model T100 boosters are a good swap, any other ones I can look for, say from the Tundra or Tacoma?

I am still looking for some past experience that the booster made lock-up possible before I make the swap though, anyone? FYI the tires are 38s.
 

·
Registered
Joined
·
362 Posts
Im going to be upgrading my brake MC to the Chevy, proportioning valve, and booster here soon as well, but I was just wondering when I order that Chevy MC setup, is the MC that comes with it new, used, or rebuilt?

~T.J.
 

·
Registered
Joined
·
16 Posts
I have been using this great page by ErikB:
http://home.4x4wire.com/erik/4runner/brakes/

You can very much use a Chevy MC with a dual-diaphram booster on a stock 85. The only hassle is getting all the brakeline adapters to go between metric and standard fittings, NAPA auto is your friend. You also need to buy or make an adapter plate to mate the master and booster together.

I also found out that Tacoma and Tundra masters and boosters use 2 bolts to hold together. Hence they won't bolt up the same way, but it can be done. The bolt pattern is about 1/2" off from that of the Chevy MC so altering the MC is an option. A new push-rod or altered one may be needed too. Also heard that Tundra boosters are only single diaphram, not sure about Tacoma boosters.

Chevy MC and Tundra booster swap here:
http://www.krawlr.com/TacoTech/brakes/brakes.html
 

·
Registered
Joined
·
16 Posts
84Toyota4x4 said:
Im going to be upgrading my brake MC to the Chevy, proportioning valve, and booster here soon as well, but I was just wondering when I order that Chevy MC setup, is the MC that comes with it new, used, or rebuilt?

~T.J.
Not sure what you get from Rockstomper. I made my adapter, and a new USA made 1 1/4" MC cost me about $67.
 

·
Registered
Joined
·
362 Posts
84Toyota4x4 said:
Im going to be upgrading my brake MC to the Chevy, proportioning valve, and booster here soon as well, but I was just wondering when I order that Chevy MC setup, is the MC that comes with it new, used, or rebuilt?

~T.J.
Bump...Still havent gotten a hold of them.

~T.J.
 
1 - 13 of 13 Posts
Top