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Unread 03-18-2009, 11:28 PM   #1
m-dub
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1977 CJ5 
 
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4 wheel disc's which MC???

Howdy all,
Done a bunch of searching with mixed results. Here is my deal:

77Cj5 on 35's with stock front disc, stock (non power)MC and porp valve and Ford Explorer rear discs (early 90's style). My Porp and MC are both leaking and need replacing.

1: I have been told that a mid 70's corvette MC is the ticket ( bigger 1" bore for more volume). But wonder if anyone has done this or is there something else others have done?

2: power assist? may require some cage mods to fit ( I have a shock hoop setup that takes up some space. Is there a disc set up for this or just the stock disc/drum?

3. Go the Willwood or Tilton custom set up?

Also: Do I just replace the porp vlave with a stock unit or go with a ? I dont want to take it out and run a adjustable block only for the sake of safety ( if you loose front or rear the other still functions )

Bottom line is I just want to do it right. I have used manual brakes that rock ( mine dont) and don't mind spending money for safetys sake ( I got the kids in the rig)

Thanks for any ideas!

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Unread 03-20-2009, 12:42 PM   #2
m-dub
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Any idea's? anyone?
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Unread 03-20-2009, 12:56 PM   #3
Hardy350
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I have a Hydrobooster with a Corvette Masterzylinder works great...
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Unread 03-20-2009, 01:13 PM   #4
jeepskate
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Corvette MC as you've found for the manual setup. For power, you need a disc/disc combo valve which you can get from Master Power Brakes, I'd go with a dual-diaphragm GM-based booster with a GM MC like a Firebird unit or I'd go hydroboost.
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Unread 03-20-2009, 01:55 PM   #5
mike06X
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is the corvette mc swap (for retaining manual brakes) one for a corvette w/ manual brakes? I know some early 70's corvettes were available factory 454s/4-speeds/manual brakes - is this the ticket? could you feel an improvement over the rock-hard factory cj pedal? any plunger, arm, etc modification to fit the corvette mc?
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Unread 03-21-2009, 12:57 PM   #6
m-dub
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^^^^^my qusetion as well^^^^^^ also, I take it the porp valve has nothing to do with being Drum disc or disc disc? just more of a "more to the front and less to the rear" deal?
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Unread 03-21-2009, 02:04 PM   #7
dawgates
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PP valve

It's not that much the master cylinder as to the proportion valve. Hopefully you switched to a power brake booster. That will help tremendously on stopping.
Find a PP valve from a Grand Cherokee with four wheel disc and use that valve. Or you can get a adjustable PP valve from SpeedwayMotors.com . This way you can adjust the pressure done on the front brakes. I think disc's run at 2 psi and drums at 10 psi.
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80' CJ7, 360 Howell Injected, 3" single exhaust, NP435 4spd, Dana 300 AA clocking ring, Currie twin stick, Tera-Low 4 -1 kit, Dana 44 front, cut 10" wider to 63", 4.10 gears, ARB, Yukon axles and Super H/D u-joints, Currie Dana 44 rear, cut wider to 60 1/2", 4.10 gears, ARB 35 spline, Currie 35 spline axle shafts, 2 1/2" x 11" Ford drum brakes, CJ-SOA conversion, Tom Woods F & R drive shafts, Warn 9500i winch, 6 point cage, Homemade F&R bumpers and tire carrier, 1" body, Pro Comp supension Kit, 12.5x35x15 BFG's, 15x10 OMF beadlocks, Body armor, OBA.

Last edited by dawgates; 03-21-2009 at 02:09 PM.. Reason: miss spelled words
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Unread 03-21-2009, 03:35 PM   #8
jeepskate
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For power brakes, you need a disc/disc combo valve as I stated. With the manual 'Vette MC, IIRC the metering is integrated so you don't need a downstream valve unless you want to plumb an adjustable into the rear line...I could be wrong on that one since I'm relying on memory from back in the late 80's.
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'83 Scrambler: time & money pit under construction with parts from CJ's,YJ's,TJ's,FSJ's,GM,Ford,IH,Honda,Toyota and a whole lotta aftermarket & custom stuff.
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Unread 03-21-2009, 04:18 PM   #9
John N
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A call to Van at Vanco Brakes would answer all of your questions. He's always glad to help, even if he doesn't sell you anything. He knows his stuff about brakes and different combinations.
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Unread 03-21-2009, 04:57 PM   #10
dawgates
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Oh come on jeepskate, you're not that old that you don't remember the 80's! Now the 60's that would be a different story!
JohnN has the right idea, a call to either Vanco or MP Brakes would solve all you braking problems.
And "OLD" I need to read all the threads for all the information, not just one or two!
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80' CJ7, 360 Howell Injected, 3" single exhaust, NP435 4spd, Dana 300 AA clocking ring, Currie twin stick, Tera-Low 4 -1 kit, Dana 44 front, cut 10" wider to 63", 4.10 gears, ARB, Yukon axles and Super H/D u-joints, Currie Dana 44 rear, cut wider to 60 1/2", 4.10 gears, ARB 35 spline, Currie 35 spline axle shafts, 2 1/2" x 11" Ford drum brakes, CJ-SOA conversion, Tom Woods F & R drive shafts, Warn 9500i winch, 6 point cage, Homemade F&R bumpers and tire carrier, 1" body, Pro Comp supension Kit, 12.5x35x15 BFG's, 15x10 OMF beadlocks, Body armor, OBA.
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Unread 03-21-2009, 05:04 PM   #11
jfwireless
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I installed 4 wheel disk brakes on my 1976 CJ7. Originally my 76 CJ7 had power 4 wheel drum brakes. I got the prop valve from a YJ with front disk brakes and used a 1981 Corvette Master Cylinder as recommended by Van at Vanco. The master cylinder bolted right up to my brake booster and the lines were on the same side as the original master cylinder. Brake lines/fittings worked just fine.

At first I just added front disk brakes, that is when I got the YJ prop valve from a YJ with front disk and rear drum. I also added the Corvette master cylinder at that time because it will work with front disk, rear drums, and also 4 wheel disk brakes.

I still have the YJ prop valve after the rear brake conversion, and all works just fine. The rear disk wheel conversion really made a big difference in my CJ.

I currently have a 1990 YJ dual diaphragm brake booster and matching master cylinder to install in the CJ along with the YJ brake pedal assembly. Just have not got around to it yet.

The brakes on my CJ are like night and day compared to the original power drum brakes. No fade, no issues when wet, faster stops and my wife isn't complaining about the brakes anymore. How about that

I bought the 1981 Corvette Master Cylinder from Rockauto. Rockauto part number is D14 18M91. Looked up as a 1981 Chevrolet Corvette 5.7L V8 4BBL. At the time the cost was $54.79.

I do not know if this Corvette master cylinder will bolt up to manual brakes.

Jim
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Unread 03-21-2009, 05:23 PM   #12
jeepskate
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Hehehe...at the point that I read about the conversion, I was still a year or two away from owning a Jeep. You know...lusting, writing lists, etc
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'83 Scrambler: time & money pit under construction with parts from CJ's,YJ's,TJ's,FSJ's,GM,Ford,IH,Honda,Toyota and a whole lotta aftermarket & custom stuff.
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Unread 03-22-2009, 09:03 PM   #13
Dad03
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Quote:
Originally Posted by jfwireless View Post

I currently have a 1990 YJ dual diaphragm brake booster and matching master cylinder to install in the CJ along with the YJ brake pedal assembly. Just have not got around to it yet.

Jim
The Vette MC works with the 4 wheel disc? Why are you changing to the YJ MC and Booster?
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Unread 03-22-2009, 10:55 PM   #14
jfwireless
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Quote:
Originally Posted by Dad03 View Post
The Vette MC works with the 4 wheel disc? Why are you changing to the YJ MC and Booster?

The 1990 YJ dual diaphragm brake booster provides more pressure than the single diaphragm CJ booster. Disk brakes like to have that additional pressure.

Jim
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