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74 Disc Brake Conversion

Discussion in 'Intermediate CJ-5/6/7/8' started by shadetreetim, Nov 15, 2019.

  1. Nov 15, 2019
    shadetreetim

    shadetreetim New Member

    Riverside, Ca
    Joined:
    Oct 2, 2019
    Messages:
    42
    A few months after buying this Jeep, wrenching on the weekends and dreaming during the week, I'm wrapping up my initial rebuild of my 74. All lights, gauges, and blinkers work now. It finally drives without wandering all over the road. Just now wrapping up the heater rebuild. Still need to address the wipers.
    [​IMG]

    But as I've been working on every other system on the Jeep, I've been researching and acquiring the parts to put disc on the front. I got the adapters from Brennans Garage and all the parts from Rock Auto.
    [​IMG]

    Not pictured is a set of Organic pads. My Jeep currently has non-power brakes. As I've searched, I haven't found much info on the intermediate Jeeps getting this upgrade. Specifically, modifying the 74 Master Cylinder for the residual valve. My plan has been to run the non-power MC initially, just pulling out the front residual valve. I ordered a rebuild kit for the MC, if I'm going to pull it apart I may as well rebuild it. The kit includes new residual valves, I'll just leave the front one out.
    [​IMG]

    But today I was looking at my existing proportioning valve. I would imagine the valve would have different valving for disc brakes.

    Now I'm thinking I may want to switch to a 77-86 Power Brake Booster / Master Cylinder setup. Looking at the 74 MC, both front and rear ports are 1/2"-20 thread. The 77-86 MC has one 1/2"-20 and one 9/16"-18 threaded port. If I run that MC I could run the 77-86 proportioning valve.

    As soon as the MC rebuild kit comes in I'll build it with the stock MC, meanwhile I will start looking for the parts I'll need to upgrade to power if I decide I need to.
     
  2. Nov 16, 2019
    Focker

    Focker That's what I do, I know things and I fix stuff. Staff Member Sponsor 2019 Sponsor

    Tri-Cities WA
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    Aug 18, 2014
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    6,217
    I can't see the pictures.

    I thought the intermediates came with disks from the factory?
     
  3. Nov 16, 2019
    47v6

    47v6 junk wrecker! Sponsor

    Washington DC.
    Joined:
    Oct 25, 2006
    Messages:
    4,629
    Started in 76/77 as far as I know. There were a couple different kinds too. I am running a D30 that originally had drums from 74 in my 2a now. Converted it to chevy brakes with a 77 thick rotor. Simple swap.
     
    45es and Focker like this.
  4. Nov 16, 2019
    shadetreetim

    shadetreetim New Member

    Riverside, Ca
    Joined:
    Oct 2, 2019
    Messages:
    42
    :):coffee:
    74’s have 11” drum all around.

    I can only see the pictures if I’m logged in. Probably I did it wrong. I haven’t posted enough to see anyone else’s pictures full size so perhaps it’s fair... :)
     
  5. Nov 16, 2019
    timgr

    timgr Jeepin' Nerd Sponsor 2019 Sponsor

    Medford Mass USA
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    Aug 10, 2003
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    20,251
    First year for front disks on a CJ was 1977, and they were optional. Apparently they became standard the following year.
     
  6. Nov 16, 2019
    bigjohn

    bigjohn Member

    Kelso Wa
    Joined:
    Mar 18, 2010
    Messages:
    376
    I'm running the 77 Mc on my 75 with 4 wheel disc's and no proportioning valve. Removed the residual valve, and an adapter for the 1/2-9/16" fitting. I personally don't see the point in power brakes on these. It's a little tough but nowhere near the hard brake like the old Ford pickups for example.
     
    Norcal69, shadetreetim and dane71 like this.
  7. Nov 16, 2019
    shadetreetim

    shadetreetim New Member

    Riverside, Ca
    Joined:
    Oct 2, 2019
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    42
    Yeah, my old 71 GMC had manual front disc. Never thought it was a problem, but that was 30 years ago. I guess we’ll see.
     
  8. Nov 17, 2019
    47v6

    47v6 junk wrecker! Sponsor

    Washington DC.
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    Oct 25, 2006
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    I love my power brakes. Disk on all 4 corners, 35" tires.. Whats not to love? Honestly, the power brakes and power steering are the best upgrades i could have ever dreamed of.

    I have driven my stock 2a for years as a daily driver with the small non v6 ross box and 9" stock brakes. Its really nice to not feel like I'm going to die at any moment. Thats the point of power brakes and steering.

    When i went to 11" drums up front on that 2a, it was night and day difference in safety and drivability. I drove my present 2a with manual brakes and disks with organic pads and its similar to the drums. The addition of power brakes and disks with semi metallic pads are night and day over the 11" drums.

    The 1974 cj5 has swinging pedals? Right? The addition of a vacuum booster would be a very minimal amount of work to install and make your brakes significantly better. If I were upgrading my system and it was this easy to add power brakes, I would do it.

    For under 200 bucks you can buy a combined booster/ master and basically bolt it right on. I had to reengineer my swinging pedals to do this in my 2a.
    https://www.amazon.com/MBM-BB-8D-7486J-Power-Brake-Booster/dp/B00GYALW7A
     
    ITLKSEZ likes this.
  9. Nov 17, 2019
    wally

    wally SSSSTER

    upper merrimack...
    Joined:
    Jun 12, 2005
    Messages:
    518
    i swapped in later d30 disc brakes into my ‘75. used the ‘75 master cylinder and removed the rubber residual valve from the output port to the front brakes. does not require huge effort to apply the brakes, and better than the original drums up front. did nothing to the proportioning valve, brakes appear to work well.
     
  10. Nov 17, 2019
    shadetreetim

    shadetreetim New Member

    Riverside, Ca
    Joined:
    Oct 2, 2019
    Messages:
    42
    I don’t have power steering and honestly can’t see the need for it. I think this 74 steers very easily, I recently added 4 degree shims to the front axle to get caster correct, so that may be part of it.

    I gotta say, with the 11” manual drum brakes, this thing stops very well too. I bought the disc brake parts before I had driven this Jeep more than a few miles. Yesterday morning I drove it 60 miles round trip on the freeway, with SoCal traffic as bad as it is. First time on the freeway with this CJ, or any CJ for that matter. Never once thought the manual drum brakes were not enough. But with that being said, I will be installing the disc brakes on the front in a few weeks though. But we have a desert trip planned for Thanksgiving weekend so I don’t want to start this conversion until we get back.

    The water pump started leaking after yesterday’s drive so I ordered a new water pump, thermostat, and radiator cap. We’ll get those installed next weekend. Top of the list.

    I also noticed today, while replacing the fan belt, that the crank pulley is not lined up with the water pump pulley or alternator. The crank pulley sets further from the block than the other two. What’s odd is the other two line up perfectly with each other. Everything looks stock on this 258, but the misalignment is almost half the belt width. Maybe I’ll order a 3 wire alternator and customize its bracket and shim the water pump pulley to get them all in alignment. I would like a higher amperage anyway to support the seat heaters I have not added yet.

    I didn’t get the new Dodge truck heater blower motor wired in this weekend like I planned to. Too many family obligations. At least I was able to drive the Jeep to one of them. Needing to install the new ductwork under the dash, it seems it would be easier to just pull the dash back out. Should have bought all these heater parts when I had the dash out rewiring everything else.

    I did install LED strip lighting across the roll bar today. Man it’s like daylight in there now.

    Hopefully next weekend is more productive than this one was.
     
    Last edited: Nov 18, 2019
    melvinm likes this.
  11. Nov 18, 2019
    sterlclan

    sterlclan Member Sponsor

    exploring the...
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    Feb 21, 2009
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    3,041
    I ran a 74 without power steering for years added it when I swapped the 304 love the one finger turns and it helps in the woods
     
  12. Nov 18, 2019
    melvinm

    melvinm Member

    Arvada Co. 80003
    Joined:
    Aug 11, 2012
    Messages:
    87
    For power brakes take A look at the jeep guy , phone 503-689-2072
     
  13. Nov 18, 2019
    Jeff Bromberger

    Jeff Bromberger Member

    Dallas Metroplex...
    Joined:
    Jun 28, 2019
    Messages:
    52
    Unless you have a 1974 Jeep DJ-5, in which case we have the older 10" drums. We didn't go to the 11" variety until 1976 or so.
     

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