CJ Brake upgrade

How does hydro boost work, as opposed to the standard power brakes which are vacuum powered? I've been warned against power brakes for off roading.

I used a Pontiac Firebird mastercylinder. I believe it was out of a 1978-1979 model with 4 wheel disc brakes. It bolted right to my booster and is a 1 1/8 bore which is much bigger then a stock jeep. I have a Disc conversion on my rear axle using chevy el camino calipers. The booster i am speaking of is from my 1985 CJ7, however it is hard to say whether the same M/c will bolt right to the booster you have.

FYI- Elliot from Brake Service Center in Newark, De is a great resource when it comes to brakes.

1968 Corvette master cylinders are supposed to be a direct replacement for a CJ as well. They came with disc brakes front and rear. Don (Jump150) is using one on his.

How will the braking holding be in the event of the engine stalling on an incline? Will the natural operation of the brakes be effected?

Ugh..my fault, they are eldorado calipers out of late 70 early 80's eldorados, not el caminos. They do have cable activated e-brakes. I cant remember which rotors are on there.

Oh yeah.... and Linyee, that was me that stopped by!!

I would never put hyrdoboost in a Jeep, its way overkill. It is harder to modulate it, and it is a VERY stiff pedal when the engine is off. I dont know where this notion of more power after the engine stops, its not true, at least in the ford system. When there is no pump turning, there is no boost. At least you have a couple of applications with a vacuum brake before you are completely up the river.

I have hyrdoboost in my truck, and vacuum in my Jeep. alot of smaller diesels use a vacuum pump off of the back of the alternator to power the brakes.

There are some smaller hydroboost systems from GM cars, but it still is alot of complexity.

You can use an E-350 master, but it leaves you with very stiff brakes. Even with power. As long as you dont mind the workout. They are pretty easy to find on pirate under "kung-fu brakes". It works with your rear drums

I believe the vette MC is for four wheel disc. If you go the four wheel disc route, you also need an adjustable proporting valve, a proportioning valve out of a 4 wheel disc vehicle (like a hummer), or a 4 wheel disc MC like the vette and no PV.

There is another option to four wheel discs, which is what i have the parts for at my house : Nissan 300Z rear calipers and sammi front discs. The nissan calipers have a very nice parking brake built right into the caliper, and the sammi discs fit with no machining.

I am running a stock proportioning valve up front and an adjustable proportioning valve to control the rear discs. The reason I am still running the proportioning valve is that I was told by some pretty experienced folk that if you were to lose a brake line while on a steep grade the proportioning valve will allow you to get enough brake pressure to the opposing axle to buy a little time before you go into total brake failure. Even with all these mods, I am not very impressed with my braking power. I can stop fairly fast, but I can't lock them up. I am not sure what the problem is.

I am fairly happy with my stopping power with manual brakes. Even when I was running the 11" drums in the rear it stopped well when they were adjusted right. I'm not running as heavy a tire as some guys are either and that could make a big difference. I'm guessing that 35" tires are probably the bottom of the range at which the stock brake system should be upgraded due to the rolling mass.

The Jeep rear discs I just put in are starting to settle. Once I got the leak fixed I had to pump them up at first but I was told by a few sources that it had something to do with rubber boot in the brake piston pulling the piston back too far until the rubber loosens up a bit.

Quote from "DieselCj"

What did you put on the rear for disc brakes? I'm

I was making the rear a full floater and because of the way I did it the Jeep discs were a direct bolt on.

Plus I hate drums. Once you have them adjusted right they're fine. If you get them close they will adjust themselves. But getting the drums off, messing with the springs, tapping the shoes into the correct position to get the drums back on.....is all a pain. I've also heard discs have better holding power on a hill, although that is probably a matter of opinion.