Scooby098

I have a little issue with my brakes. there just not really there, and if I stop while the truck is running they will drop in pressure and sometimes drop off completely untill they get pumped up more. So Im thinking its the booster or master, or could be the lines. My questions is there really a big improvement with the 1 inch bore of the v6 master ? or would I be good just going with a rebuild one for 30. ? thanks for the input.

jason191918

Are you losing fluid?

Yes=leak

No=bad MC

my .02

Scooby098

yah fuild is good
havnt had to refill it since it started and it was good then one day it kinda just pushed through. so should I upgrade? or just go with stock?

dropzone

iTrader: (6)

you could also be losing fluid through your wheel cylinders or calipers. Inspect all of your lines etc...

Increasing the diameter of your master cylinder is a great idea especially since you are running 36" tires. Running that size tire you are putting a straing on a brake system that was designed for 225/75/15's ( about 28" tall) You should consider upgrading to IFS calipers and Vented rotors IMO...
If you do swap out your MC besure to search bleeding the master cylinder, not the easiest thing to get right...

edit: just found this cool idea over on Pirate: swap in a dual diaphram booster from an 86-87 turbo truck, direct bolt in and the guy says he can lock up 38" tires-- http://pirate4x4.com/forum/showthread.php?t=689905
-- part # from napa for both 2 and 4 wheel 532460

jason191918

He said the fluid was fine.

Scooby098

that booster looks like a nice idea now to find someone who has one... the yards all around here are out of yotas. there all being scrapped sucks.. so you think upgradeing to the v6 MC would be a better option? im eventully going to upgrade up all the v6 I can from Trail gear. I just refreshed my rear brakes new pads and etc.

tesseract620

So I'm in the same boat as the OP, I'd like to upgrade as well.
What type of master cylinder should I be looking for? I'm gonna see if I can find one of the dual boosters, will a V6 master cylinder bolt up?
Will the master cylinder for the turbo'd dual booster be better than stock? I've got an 80 yota

tesseract620

Ps, I realize this thread is super old, but I've been looking around on here for a few hours trying to find solid answers, (been side tracked a few times by build ups, not gonna lie, LOL) thought I'd revive the thread and see if anyone bites..

waskillywabbit

iTrader: (-1)

80 model has weird wheel hubs. Not sure you can use off the shelf vented rotors.

:wabbit2:

541SR5

I did some reading on Pirate and the V6 M.C. from an 89-94 4X4 truck or 4-Runner will work (non-ABS). What I am wondering (and hopefully someone will answer) is will the plug for the fluid level sensor plug up, or do I need to splice in the old one.

I should have the M.C. and dual booster in this week sometime and and put on this weekend. Then I'll have my '81 brakes completely upgraded (vented rotors, IFS calipers, etc.)

dropzone

iTrader: (6)

I remember something about the 79-80 being different two.
I will see if I can get pics at a friends house sometime.
He has a 79, 81 & 83 in his driveway...