CJ3b....That is what the vin tag says.

[jmichael]

This might help understand the leverage concept. Think of a winch. If you pull with just a straight pull you get one kind of leverage. If you put a snatch block at the connecting end, you have the same pull from the winch, but twice the over pull from the line. In the second instance, you are pulling only half the distance with the same force, thus double the power. It works the same with our brake master cylinders.
I have probably totally botched this explanation, but that's my 2 cents worth.

Mike

[jonah]

Thanks, I think I have the concept down. I will swap out the 3/4" to the front and give it a try. My Wilwood pedal set up has a "balance bar" that can also adjust the bias, but I have it adjusted all the way for the front now and it wasn't enough. Hopefully the 3/4 for the front will get it fixed.

I will keep an eye on the fluid level in the reservoir too. I have the larger size reservoirs so hopefully it won't be an issue.

[jmichael]

If you're not familiar with how the balance bar should work let me know, I've spent hours working with that set up. Many times people position the push rods too close to the pedal, not leaving any slack on the ends to allow the center rod to pivot. Make it sloppy on the ends. And the closer the fulcrum point is to the front cylinder the more forward bias.
Mike

[jonah]

Well, I just started messing with it. My understanding is that if the pivot is centered you get equal pressure on the master cylinders. If you adjust the pivot toward one master, that master will receive more pressure.

Sound right?

I started with it centered, and moved it toward the front master. But really, I didn't notice much difference. But since my masters are switched, it was probably too far out to bring in with the balance bar.

[6spdYJ]

Just to be clear, with a dual reservoir master cylinder the rear bowl feeds the fronts and the smaller front bowl feede the rears. A lot of people try to complicate hydraulics. You need to look at surface area within each cylinder. If you increase the master size, the amount of pressure at the wheel is increased. If you increase the wheel cylinder size the pressure at the wheel is decreased. Consider two common items, a coffee can and a soup can - both filled with water. If you stack the soup can on top of the coffee can, the suface pressure to the ground per square inch of the coffee can doesn't increase by much because that load is spread out over a larger area. Now put the coffee can on top of the soup can. The weight remains the same, but the surface pressure to the ground under the soup can raises tremendously because the square inch area is smaller with the same weight applied. Where most people get confused is the concept of volume. Bigger is better right? Another way to look at it, two Jeeps of identical build go into the same mud hole. One has 175/55-15's. The other has 33/12.50-15's. Which will sink first? The one with the higher pressure applied per square inch of tread contact.

[jonah]

Hey 6spd,

I am running two separate masters, one for the front and one for the rear.

You actually gain psi by going with a smaller M/C. If you have a M/C with 1 square inch of surface area and apply 100 lbs of force to it you get 100 psi. If you apply 100 lbs to a M/C with 2 square inches of surface area you have 50 psi. That is why moving to a smaller M/C gives you move leverage. Now because the bore is smaller, you need a longer stroke to move the same amount of fluid, but that is a separate issue and only really matters if you run out of master cylinder stroke.

There is actually a good article on the subject here:

http://www.hotrodheaven.com/tech/bra...kes1_index.htm

[aw12345]

Sounds like you have no brake booster, which makes for horrible brakes no matter what you do.
A hydrovac might be a solution or a gm hydroboost the latter might work well to give it good brakes, it's small and gives a lot of brake pressure, would be a lot of work to make it work, but would be well worth the effort

[jonah]

Art, you are of course right. Manual brakes, what was I thinking... well I know what I was thinking - "I am keeping this jeep simple and they use these manual dual M/C on racecars, so they must work". The fault in my logic was, race cars care about going, not stopping! duh.

Anyway, no room for a vacuum unit. I could fit a hydroboost but the work it would take is huge. My whole pedal assembly supports my steering column and the clutch pedal, so I would be starting from scratch on steering support, clutch pedal and brake pedal as the wilwood pedals can not accept a booster of any kind. I might have to do it, although it is not bad with 33s, if I go to a bigger tire someday I am sure I will have to do something.

They do make these cool little electric inline boosters, but they are kind of pricey. Although I am going to look into them further.

In the meantime I am doing right leg squats like crazy!!

[jonah]

Art, thanks! I just started reading about hydrovac units. I was thinking only of the type that mount to the master. I didn't know about the inline style of booster. I am just starting to read up on it. Anything I should know? I still don't know how it would work with a double master set up.

[aw12345]

You would want a regular master cylinder preferably, but as handy as you are I am sure you could make it work with your double setup. Especially if you ever stuff 35's under there you want some sort of brake booster.
That or a giant block of concrete on a chain lol

[jonah]

LOL, for 35s I recommend one giant cement block, now if you want to get up to 40s...

Yeah, we will see how it goes. I don't know why I didn't go with power to begin with.

[RAT]

You would want a regular master cylinder preferably, but as handy as you are I am sure you could make it work with your double setup. Especially if you ever stuff 35's under there you want some sort of brake booster.
That or a giant block of concrete on a chain lol

I wonder if you can adapt a 2002 TJ master cylinder to your jeep. I have the stock one out of mine with the vacuum assist. I think all you would need will be the proportioning valve.

[jonah]

I don't think I have room for a firewall mounted vacuum assist. But I might break out the tape measure tomorrow to see. The engine compartment is narrow on that thing. But if it did fit, the big thing would be finding new pedals and building another hanging pedal assembly. Doable, but a lot of work. If I was going that far I would probably go up to a hydroboost system, and 60s and 37s...

I was looking at the Astro van hydroboost M/C on the web today. It looks nice and small, that could work.

Anyway, I think this wilwood system will be fine for my 33s, I just need to get it dialed in. If my leg gets too tired, I will worry about it then.

[jmichael]

Jonah, I read your entire thread and noticed a picture of the radiator you are using, but I couldn't find any information as to what it is. Can you tell me what the radiator came out of? I am going to run a Buick 231 in my flattie and I need the same radiator.

[jonah]

I am not sure. It came with the jeep when I bought it. The motor is a 71. I kind of figured it came from a similar vintage CJ, but I never tried to figure it out. I can grab some measurements when I get to the shop this afternoon.

I was thinking about upgrading to a cross flow after seeing SNOOPY's CJ5. He had a two or three core cross flow made about the same size, but I can't recall the tanks he used. Mine is single core. So far it seems to be working, but I wonder about when it gets hot outside.