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Unread 04-03-2014, 11:20 PM   #1
moranda
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Power brake conversion vac vs boost

My jeep has had a leaky master cylinder since I have had it. Every time I drive it the master cylinder body will have a coating of brake fluid on the outside of it. Well as of recent my power steering pump has sprung a pretty good leak in it too. The jeep does not have power brakes. I guess what I am trying to ask is should I go for a hydro boost setup or should I just get a typical vacuum style master cylinder/ diaphragm? I plan on sticking 35's on it eventually. Anyone one who has experience or advice with either please chime in. Trying to see the pros and cons of each to help me better decide.

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Unread 04-04-2014, 01:05 AM   #2
TIPPEDITOVER
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I have done a considerable amount of research about hydro boost and I'm just going to stick with vacuum boost as I have now. Hydro boost is just something else that can leak and make a big mess under the hood. The stock CJ vacuum boost/master cylinder stops my CJ5 on 38's with zero issues, so there's no reason to get complicated. Granted, I have 4 wheel disk brakes with larger rotors/calipers than what was stock on a CJ and that did make a big difference.
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Unread 04-04-2014, 01:20 AM   #3
dg6772
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Tippeditover, do you recall the cost of the larger rotor setup? I have 4 wheel disc on my CJ7,for just the cost of the parts. A couple hundred bucks. The rest I did myself. It might help the other guy if he had some kind of idea on cost between the two he is considering.

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Unread 04-04-2014, 01:24 AM   #4
TIPPEDITOVER
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What I have on the front D44 axle is Ford 1/2 ton rotors with 1/2 ton Chevy calipers. On the Ford 9" in the rear I put 12" front rotors off a 2001 Ram and Cadillac calipers. Also considered Chevy 1/2 calipers on the rear too, but wanted the parking brake mechanism in the caddy calipers. Caddy calipers were $60 apiece. Chevy calipers were $28 apiece. Each rotor was around $40

Photo of rear rotors/calipers with 15" wheels. Surprisingly never rubbed once. I now have 16" wheels with MUCH better clearance. Made a cardboard template and then cut the caliper mount brackets out of 3/8" material with my oxy/acet.
imag0114.jpg   imag0117.jpg  
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Unread 04-04-2014, 12:20 PM   #5
moranda
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I have stock disks and calipers on the d30 and drums on the rear. Even though the drums have been worked on I feel like they're not that great. Doesnt really hold with the ebrake on and I know that could just be a cable issue. Wasn't planning on swapping drums for rotors. I have the amc 20 rear and feel like it could be costly to swap.
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Unread 04-04-2014, 12:31 PM   #6
dg6772
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Its mostly going to be what you want. I'm happy with my quad disc setup,but will look to upgrade for a little more break pressure as it doesn't act like I think out should.

Cost was a big thing for me. I am a diy guy,and will upgrade as things fail under trial and error.

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Unread 04-04-2014, 12:32 PM   #7
TIPPEDITOVER
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Back before when my CJ was stock and set up like yours I had problems getting it to stop with 33" tires. That was with vacuum boost, every thing else same as yours. During tear down for the new axles, I did notice gear oil had found it's way onto the AMC 20's brake linings. That couldn't have helped anything. IDK, there's alot of people on here that run stock brakes even on 35's and don't report problems.

You had recent work done, better re-check everything. The brake fluid you see on the outside of the master cylinder could simply be from a leaking lid gasket. Make sure what you have is working correctly first. Once you determine everything's good, then if it's still not enough, vacuum boost it.
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Unread 04-04-2014, 12:50 PM   #8
rsg1963
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You asked for opinions on both so here is mine: I've owned no-assist CJ-5's, and vacuum assist CJ-7's. I've had hydro boost on my current CJ-7 for 11 years now. I rock crawl, tire pit, mud hole, sand dune and daily drive the heck out of her. Not a single issue. Very tough and far more effective than vacuum. Also, the unit is not as much of a compartment hog as the vacuum units. One word of warning though, the difference in stopping power is borderline rediculous. If I were to ever actually slam the brakes on, I would most likely break something on the Jeep. (only a slight overstatement) The units are just that strong. I run 35's on stock axle housings and it makes zero difference to the brake setup. I will never own another Jeep with stock assist after experiencing hydraulic brakes. It's also one of my 'top 3' best mods.
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Unread 04-04-2014, 01:15 PM   #9
OrangeCJ-5
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rsg1963, Where did you get the hydro assist and was it a setup off of another vehicle?
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Unread 04-04-2014, 06:16 PM   #10
moranda
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Also can you tell me what the other two top mods are? Just curious.
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Unread 04-05-2014, 05:47 AM   #11
Parabellum
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I just did the thin disk ('98?) tracker rotor with ('85)300zx rear caliper with ebrake and added a ($160 fleebay) dual 8 inch diaphram corvette master bolted directly to the firewall and am really impressed how well the 35s stop. All new parts less than $400, stopping....... Priceless.
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Unread 04-05-2014, 10:43 AM   #12
TIPPEDITOVER
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Quote:
Originally Posted by OrangeCJ-5 View Post
rsg1963, Where did you get the hydro assist and was it a setup off of another vehicle?
Chevy Astro van hydro boost is what a lot of people use. I've got one sitting in my garage now that I pulled out of the junkyard for my CJ. I even went and bought all the hydro fittings and hoses to install everything. I found that when I installed the new axles with the larger rotors/calipers it was not needed.

There are certain advantages to using hydro boost for certain people. It uses less space under the hood and provides more assist than the stock vacuum boost does. For people who don't plan to upgrade their axles, it would help them get better braking by increasing the amount of pressure available in the lines/calipers. More pressure = more force. More pressure = harder on everything in the braking system. Too each their own though. Hydro boost tends to be grabby sometimes as well. Got it in my diesel truck. When you begin to apply the brakes it feels like nothing, nothing and then bam. Smooths out after applying the brakes a few times.
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Unread 04-05-2014, 06:47 PM   #13
Spieg8
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A hydro brake offers the most bang for the buck in my opinion. If you are going to run 35" tires or greater, it's the only option that will give adequate stopping power on a stock disc/drum setup.

As mentioned above, more pressure can potentially cause more wear and tear on brake components, but that's really only an issue in the event of an emergency/panic stop which doesn't happen often. Under typical driving conditions, you're not applying any more pressure than a normal vacuum assist.

I know a lot of people are using the hydro setup out of an GM Astro/Safari van, and a Ford Mustang is also a popular donor (can't really say which would be a better choice).
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Unread 04-06-2014, 08:34 AM   #14
moranda
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Thanks for all the input guys. I have also seen that a company called vanco offers a hydro boost setup that is new. Any one have an opinion on these getting a new setup vs getting one off astro/mustang? Would going new be worth the $$ vs going pull a part?
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Unread 04-06-2014, 09:11 AM   #15
Matt80cj
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Has anyone tried/considered a hydro boost from a 1 ton? I know Chevy has put them in anything with a diesel or any 1 ton. Would it work?
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