Minitruck Brake Booster Marlin Master Cylinder Writeup

[1973Guppie]

Thought I would do a short writup in one thread that shows my solution to my MC and brake booster going bad and what I did for a solution. I found alot of info in the threads but none in one place.


PARTS:

Booster: p#53-2460, from 81 toyota pickup
http://www.partsamerica.com/productd...tNumber=532460

power brake check valve: p#80190, help! item from local autoparts store
http://www.partsamerica.com/productd...rtNumber=80190

Master Cylinder: From Marlin Crawler, FJ80 non usa master made to be used on 4 whl discs.
http://www.marlincrawler.com/htm/brakes/mcylinder.htm

* p#'s are standard and can be looked up at any autozone, kragen's, etc.


Findings:

- flaring brake lines is a bitch, get a good tool and a lot of tube, the black colored tube flares easier and bends much easier than the silver stuff. It takes awhile to get a flare that will hold. I have been told that the hydraulic flaring tools are the way to go if you are going to do a bunch of flares, but they are expensive.

- take a good look at your booster when replacing a leaky MC. My MC was leaking just a bit between the MC and booster. After I got the whole shebang back together with the old booster I found out that the brake fluid had leaked into the old booster and had killed the seals. If your booster is old, and soaked from brake fluid, you may want to consider just replacing it.

- when installing the booster, make sure your pads are not dragging. If so they will smoke like mine did! I ended up having to space the MC away from the booster about 1/4 inch using some M10 nuts, worked fine, not the cleanest solution but hey, it worked. Another cleaner solution may be to either pull the booster rod and shorten it, or make custom plate spacer out of 1/4 plate. I could not get mine out and didn't want to break anything so I went with the spacing solution. The other mc rods i had from my older booster would not work as they were thicker than the new 81 minitruck booster rod. I tested to make sure things weren't dragging by letting the car roll down the driveway. you may not have to do any of this with the stock or another booster. The marlin MC flange is thin, and the stock MC flange is much thicker, so it just dpends on the setup you have.

- check valve: found one at the local parts store and just put together some hose attachments to make it work. I used some step down pvc couplers to move from a larger hose to a smaller one and vice versa. I did some research and the check valve IS NECESSARY. Basically the check valve ALLOWS vacuum through it but not pressure, so if your engine dies, your booster will not lose vacuum and you will have at least a few pumps of your booster to help you stop. I thought this was important.


Conclusion: This setup is much nicer than my stock setup. Wow, quite a difference. The above booster is a double diaphram unit, not a single diaphram unit like stock. The bigger booster gives much more boost. There is a nice bit of play at the top of the pedal which is nice, but I can now stop on a dime. I am very happy with the setup, attached are some pics.

Let me know if anyone has any questions, or if I missed anything.

Noah

[pjohnson]

You didn't mention your rear proportioning valve. Is it necessary with the FJ80 MC designed for 4wheel discs?

I just replaced my booster after doing the MC a while back. It's almost scary how touchy the brakes are now. If I try, I can lock the right rear, so I'm wondering about a prop valve.

Phil

[1973Guppie]

the prop valve is necessary when running 4 whl discs, has nothing to do with the kind of master cylinder you are running, checkout summit racing or jegs, they sell a couple types, easy install and they do help keep the rear from locking up. I usually just set mine at 50% and leave it be, has worked for awhile now.

Noah

[dukebluerog]

this write up rules!!