Master cyl. Swap

[BUKI]

Ok so when you add larger tires you go from ok stopping distance to "whew, that was close". Then you add 4 wheel disc and you get. "please god tell me my will is up to date". So I've done a little research on the web and found I'm not the only one having these issues. I have a yj with 4l. 
Now there are a few different options for larger master cyl that will bolt up with few mods

1. Ford e350 van 80s era but you need to get adapters for the fittings.

2. Mercury marquis circa 1978 with hydro boost

3. Some corvette. Can't find much on this one though

4. Dodge ram 3/4 ton. BUT I think this Is for tjs

Has anyone done this and what was involved/opinions??

[raf2379]

Durango/dakota - A1C132967 1999-2001 i've seen people use this MC. I'm searching through my book marks, I had some good info on the corvette MC.

[Bnine]

You need to read up on some brake tech Mike.

Bigger master cylinder = less power but more fluid

You want to run the smallest master cylinder possible, while maintaining enough fluid to fully operate calipers.

Brakes performance is directly related to pressure. Pressure to the pedal is delivered to the mc, which is output to the braklines. A 1" (common jeep mc) will output roughly 1400-1700psi.

Same pedal pressure to a 1.5" mc (dodge ram, ford e350) will only output about 700 psi. You have the same pedal pressure being applied to a much larger area. Therefore increasing fluid movement, but significantly decreasing output pressure.

The only "upgrade" for you is a 95 master and booster combo if you have an earlier YJ. The 95 is the first year of the double diaphram booster, and has more power.

Or you are into big money brake kits, or wj swaps to get more brakes.

If you have an automatic there is a larger booster available off a dakota that will increase pressure by about 25%. But it wont fit if there is a clutch mc present.

If I were you, I'd look for the 95 mc and booster. If you already have that, I would look into your existing brakes and see what the problem is. Stock brakes should be pretty good up to a 35" tire.

[Bnine]

Durango/dakota - A1C132967 1999-2001 i've seen people use this MC. I'm searching through my book marks, I had some good info on the corvette MC.

Durango mc's are 1.0625" and 1.125" depending on the one you get.

You dont need a durango MC unless running large calipers, but the durango mc's are the best ones to use if you are. That way you can step up the fluid displacement in the smallest steps possible. And they are bolt in for tj's and 95 yj's.

[raf2379]

here is the the 70's vette MC write up i was talking about for large tires and dual piston callipers. I havent done much reaserch into this swap my self, its something i bookmarked a long time ago

http://www.bsfab.net/?p=58

98 xj came with dual diapham boosters as well, could be a good candidate.

[BUKI]

Wow, this is Alot more than I had bargained for . Hey Bill ya got any 95 boosters layin around . I'll try looking for that and maybe go with some more aggressive hawk pads or something. Any other suggestions??  And Thanx for the replies guys

[vantagetes]

Does a YJ have a portioning valve?

[mike s]

My '94 YJ does have a proportioning valve, and I know how you feel about poor stopping power with a stock brake system. I couldn't lock up my tires until the snow hit the ground.
After some research, I'm going to try a different pad compound with more bite to it. Everything from the proportioning valve down is new on mine, but I haven't been happy since I installed it.
Talked to Napa's brake rep and he stressed staying with OEM pad compounds. Performance brakes tend to work great hot, buy you'll drive right through the first red light you come to in the morning until they get up to temp.

[Bnine]

The black magic pads Blaine deals at savvy Offroad work well and are a significant upgrade. They are a bich to break in, but worth it. I have order coming up. Tell me now if you want some.

[BUKI]

Yes. I assume these are reasonably priced?
Edit. You know what you can't put a price tag on safety. As a new father I guess this is the responsible thing to do.

[4Banger_madness]

if the booster and master from a 98 xj will work i have one if your in need.

[Bnine]

What year YJ Mike?

[BUKI]

It's a 91

[Bnine]

Ok, as long as you dont have two peice knuckles. You are good.

Missed the window for shipping. I'll see if anyone else wants any.