I have Chevy 1/2 ton brakes on the front, Cadillac El Derado calipers on the rear and am running the stock master cylinder and combination valve. I have bleed the lines and adjusted the rear calipers. I even tried removing the little rubber o-ring in the combination valve and my pedal still goes to the floor with little rear action.
Is there a bolt on master cylinder made for 4 wheel discs that will bolt up??? I heard a Ford Explorer master is a bolt up, but want to be sure.
I also want to do a dual diagphram booster. Anyone have good donors with minimal adjustments???

Currently running the same brakes with a 79 Merc Grand Marquis 4wd disk brakes with hydro boost Master Cyl. Using a stock 89 YJ booster. I have decent brakes. Now looking at a different booster. Wondering about the exploder booster...

I have a 79 Bronco Master on a stock YJ booster with the o-ring pulled from the combo valve. I have D60 front GM calipers and 1/2 ton GM rear calipers. My pedal is a little mushy at first but then :eek: hold on.

This may seem like a stupid question, but have you made sure your calipers are not upside down? If they are, then you will have no brake pressure.... just an idea.

I'm looking at a master cylinder swap for my YJ also.

I've heard of the explorer swap, but will it add a longer stroke, thus more volume?

I saw an add for willwood master cylinders in a mag but from the specs my friend and I realized they have a smaller diameter and shorter stroke than stock YJ, at least from what they listed.

Rockslut, how'd you stumble onto this swap? What's the stroke/diameter comparison to stock master? Any other possibilities you've run across?

I'm running Ford 60 (big ass dual piston calipers) and 3/4 ton 14 bolt drums (I know, money is tight though). I know my stock master won't cut the mustard volume wise and was looking for a master swap while still retaining the YJ booster.

Get a master cylinder from a late 70's ealy 80's Trans Am. These cars came equiped with 4 wheel disc brakes. You will eliminae the proportioning valve as well. Try it with in place first.
Also the Cadillacs with 4 wheel disc.

I am using the stock master cyl/booster in my YJ. I'm using 11" disks and waggie front calipers an all four corners. It works great, I can lock up 35" swampers. Like Rockslut, its a little mushy when you first step on it, but they grab with VERY little petal pressure.
-Wide

i have a chevy d60 front and 14 bolt rear with boyce equipments disc conversion. i am using the stock stuff with the o ring pulled. it works fine and as they stated the pedal is a little mushy at first but it stops on a dime

The best thing that I did even when I had 1/2 ton front brakes and drum rear was to pull the o ring out of the comob valve. It increased the rear brake pressure and volume by a ton. I used the bronco master because it was larger and bolted up with the only modification being the end of one brake line had to change sizes. I am very happy with the way the brakes work with the new axles.

I was thinking about going hydraboost but will probably stay with this setup. The 70'-80's trans am master is a good idea too.

I used the master cylinder and the booster out of a heavy chevy van. It works great.

Hey bigjeepinyj you got a write-up anywhere?

If not could you maybe post some details about the swap, other mods that had to be done, etc.

easy fix, run the front lines off the master, thru the proportioning valve, run the rear lines off the master into the jeep's cab, connect a Willwood adjustable proportioning valve next to your shifter, run lines to the rear calipers, block off the stock prop, valve rear holes with bolts and bleed the system, you now have full control of the rears, tighten up for when wheeling down an extreme hill or drop off, or loosen off the valve for wheeling up hill so you dont pull any wheeies. really effective, no soft pedal, i use this in my cherokee, i converted the rear 44 to disks with grand cherokee stuff.

Well I dont have a write up about it.

The booster and the master cylinder is mounted in the stock location as the original setup. I have 38.5 tires now and it stops it all rather well. I am installing a 14 bolt and Discs in the rear this weekend. I will see how it works on 4 Discs soon. I dont remember what year van it was I will have to go home and look at my paperwork. I think that it was late 80's but not for sure.

exact same sheit on my xj, and the 85 ford bronco (full size) / F150 master cyllindar bolted up to the stock booster lines and all, all I had to do was adjust the pin that is inbetween the booster and MC, mine just happened to be adjustable.

I'm running dana 60 front dual piston calipers & a Corp 14 rear with 3/4 ton chevy calipers with 42's.

Using a 84 corvette master cylinder, had to widen the mounting holes on the master cylinder a little and shorten the push rod a little. Works great:)

Thanks bheadrick for the tip. Did Camaro's and corvettes have the same break set-up? I know there are quite a few camaros but no vettes.

I'm heading to the u-pull it's this weekend looking for a

late70s-mid80s Bronco/f150
Late 80's Chevy Van


Any other suggestions?

I don't know about the Camaros, but the vette master cylinder has large bowls for both front and back and move alot of fluid.

Mine runs right back though the factory lines and proportioning valve. Everyone else I have talked to that run this set up deletes to prop. valve. Mine works well the way it is so I decided no to screw with it any more.

About forgot, it's mounted directly to the YJ booster. Bought mine from Auto Zone with a lifetime Warranty. Could never find one I felt good about from a bone yard.

Good Luck:usa: :usa: :usa:

Originally posted by bigdude
bheadrick- what year vette is it for?


From his post:
"Using a 84 corvette master cylinder"

:flipoff2:

I deleted it fawker, sorry

'84 'vette master cylinder will be here Friday. That bitch was expensive $115 w/o core:eek: :eek:

Oh well I guess stopping is worth it:D

I used a 77 Scout master, just removed the residual pressure vavle from the rear outlet. 1 1/8" bore. Had to wobble the holes a touch to mount it to the YJ booster. Little mushie, but then comes on good.

Hey Bigdude:

Just use your YJ mstr. cyl. for a core.

Later,

Just use your YJ mstr. cyl. for a core.

I talked to the guy and he said he doesn't give a sh-t, he'll just stuff it in the box and give me the $60 credit for the core. I wonder how this stuff finally gets figured out.

You have to wonder who finally opens the boxes and finds a Jeep master cylinder when it's are supposed to be from a 'vette. :confused:

I'm running dual piston Ford Calipers front and rear. G20 Chevy van booster, and mid 80's Vette master cylinder with the stock proportioning valve. Stops on a dime and the pedal is firm. Proportioning is perfect.

My front axle is 4" forward and my rear axle is 2" rearward. I'm at 2100# front, 1900# rear, fully loaded with wife, kids, tools and spare parts.

The booster is almost a bolt in. I had to enlarge the holes in the mounting bracket slightly and I used a Ford brake light switch on the pedal that I picked up at Napa. The Vette master cylinder bolts right in and all I had to change was the ends on the brake lines to match the master cylinder.

I used a Ford brake light switch on the pedal that I picked up at Napa

I'm not following you on this one. And in case you couldn't tell this is the first time I've fawked with Master cylinders and Boosters.

The stock wrangler brake light switch on the pedal would not work with the G20 van booster rod. I don't remember now why, it's been 5 years.

I went to Napa and tested several switches before finding one from a Ford application that worked. I saw several that were similar from Chevy's so I'd bet there are many possible combinations that would work. I think the one from the Chevy van would have worked but the terminals were broken when I removed it.

I should have said it's one of the little details that gets overlooked when swapping things around.

WTF, I just picked up the vette master and it has 4 ports, do you just plug two of them? If so which two. Also it didn't come with a reservoir, which really pissed me off. The guy told me only new ones come with reservoirs and a new one will cost me $210.

I took it for now but e told me I could bring it back. I'm heading to the pick n pull now to look for an f-150 master and a reservoir to fit this vette one.

Do I need a 'vette reservoir, or will any old one that fits work?

Mine has 30169 - AC cast into the bottom. It has 2 ports with a resevoir. I was told the application was mid 80's vette. You may be able to cross reference this part to it's application. If you want pics I can post for you.

I took that bitch back. My guess is they ordered the wrong one, besides that no reservoir sh-t was ridiculous.

I just hit the pic 'n pull and grabbed a couple different master's for $5 each.

Got one from a 20 series chevy van

Got one from a ford van that had dual piston front calipers and dana 60 drums in the rear.

I'm using the Ford van master. It's bore is 1/8" bigger and stroke is 1/8" longer than stock YJ. That's ~45% more volume than stock. Hopefully it'll be enough (it looks good on paper). All I have to do is wallow out the mounting holes and it'll bolt right up to the stock booster.

Now I wish those damn beadlocks and SOA springs would show up:mad3: