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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 Member 2020 Sponsor

    Riverside, Ca
    Joined:
    Oct 2, 2019
    Messages:
    83
    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 2019 Sponsor

    Tri-Cities WA
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    I can't see the pictures.

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

    47v6 junk wrecker! 2020 Sponsor

    Washington DC.
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    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.
     
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  4. Nov 16, 2019
    shadetreetim

    shadetreetim Member 2020 Sponsor

    Riverside, Ca
    Joined:
    Oct 2, 2019
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    :):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 2020 Sponsor 2019 Sponsor

    Medford Mass USA
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    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
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    398
    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 Member 2020 Sponsor

    Riverside, Ca
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    Oct 2, 2019
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    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! 2020 Sponsor

    Washington DC.
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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
     
    shadetreetim and ITLKSEZ like this.
  9. Nov 17, 2019
    wally

    wally SSSSTER

    upper merrimack...
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    Jun 12, 2005
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    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 Member 2020 Sponsor

    Riverside, Ca
    Joined:
    Oct 2, 2019
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    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

    exploring the...
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    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
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    Aug 11, 2012
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    For power brakes take A look at the jeep guy , phone 503-689-2072
     
  13. Nov 18, 2019
    Jeff Bromberger

    Jeff Bromberger Straight outta Bellevue! 2020 Sponsor 2019 Sponsor

    Dallas Metroplex...
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    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.
     
  14. Jan 14, 2020
    shadetreetim

    shadetreetim Member 2020 Sponsor

    Riverside, Ca
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    Oct 2, 2019
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    [​IMG]
    Haven't gotten around to installing the disc brakes yet. Just finished upgrading intake, carb and exhaust, plus a few other things. Now I've got a trip this weekend to take this thing out and play with it. As I was working on it though, I grabbed the drivers side front wheel at the top and I can move it in and out a little bit. I think I'll gather the parts to replace the ball joints, tie rod ends, etc on the Dana 30 while I am installing the disc brakes. Might help with the little bit of wander I have going on too. Anything else I should do while in there?
     
  15. Jan 14, 2020
    jpflat2a

    jpflat2a what's that noise?

    Riverside CA
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    Jul 30, 2003
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    I'd address the front wheel bearing/slop in the wheel before this weekend if it were me.
    Doesn't take much effort to get to the wheel bearing.
    The other steering/suspension stuff I wouldn't replace unless you see an obvious problem.
     
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  16. Jan 22, 2020
    shadetreetim

    shadetreetim Member 2020 Sponsor

    Riverside, Ca
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    This afternoon after work I decided to take apart one side and inspect the bearings while installing the Brennans Garage Suzuki Disc Brake conversion parts I had purchased a while back. Bearings looked good so I repacked them and reinstalled.

    The Suzuki parts installed like they were stock. I was impressed with how easy everything went together. Brennans adapter is a nice piece of steel. But now that the disc brakes are installed I have two issues.

    First one is the rubber brake lines I purchased are way too short. The line is only 12" long including connectors, and to fit well should be twice as long.

    Second challenge showed up when reinstalling the wheel. I have stock 15" rims, and plan to keep them. I don't want mags, or wagon wheels, or anything else. But the wheels hit the caliper before the wheel seats on the hub.

    I'm halfway tempted to just put the stock brakes back on. The two times I've had the Jeep out on the trail, brakes were never a concern. But as good as stock is I know the disc would be better. So my other option may be to order some spacers and try that. The spacers would also solve the rear tires hitting the inner fenderwell during full compression due to the 31x10.5 tires. Although spacers may put the tires into the fenders instead. Still, this is the solution I'm leaning towards. Just trying to decide which width spacers to order. Anywhere from 1" to 2" are readily available.

    If I put spacers on, the spare tire mounted on the side would have to go. Otherwise it would have to be spaced out as well, and it's already a pain in the butt to have it hanging out there. This past weekend I was dragging the spare tire down a canyon. I was already wanting to move it. I found an early aftermarket rear mount swing arm on ebay and bought it.

    Fun stuff.
    [​IMG]
    [​IMG]
     
  17. Jan 22, 2020
    Iandavidh

    Iandavidh Member

    California
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    Sep 24, 2018
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    I’d say space it. There are similar looking steelies on the web with a huge range of sizes but they aren’t “original”
     
  18. Jan 22, 2020
    shadetreetim

    shadetreetim Member 2020 Sponsor

    Riverside, Ca
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    Oct 2, 2019
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    Yeah, I think I'm going to do that. Looking over Brennans Garage parts list, it seems I overlooked a key word for the brake line. I bought the S10 lines, which are recommended for caliper to axle applications. :banghead: I want a caliper to frame solution. Brennan used an 85 Accord front line on his flat fender. I haven't found the specs on that application, but it looks like its about twice as long as my S10 lines.
     
  19. Jan 23, 2020
    4wealn

    4wealn Member

    Ontario, Canada
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    Nov 15, 2013
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    129
    Old school chevy blazer lines work too.
     
  20. Jan 24, 2020
    BadGoat

    BadGoat How High Can You Climb?

    St Croix, USVI
    Joined:
    Apr 27, 2017
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    104
    I used Chevy 10 bolt axle disc brakes on the conversion for my Dana 44 front. My 15 inch turbine rims barely clear the caliper. It's close enough that I can't use tape weights. I had to use wheel spacers on my rear axle to clear the Cadillac calipers. When did Jeep go to 15 inch wheels? The originals on my 65 where 16 inch.

    As a side note, I used -3AN adapters on my calipers and my hard lines, then bought custom length -3AN brake lines from Russel. Pegasus Racing had the biggest selection of fittings that I could find. I know it's not a part store solution, but it makes for a nice clean package, and I can easily change to another length brake line if necessary. I'm running wider axles and long travel shocks in front so a standard length brake line would have been too short.
     

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