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Brake Assembly And Booster

Discussion in 'Builds and Fabricators Forum' started by shaun, Feb 16, 2020.

  1. Feb 16, 2020
    shaun

    shaun Member

    Lebanon, Ohio
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    So came across a situation with my project. Have 62 A1/Cj5 with 225. Installed Saginaw Ps and disc brake conversion already set in place with 8” booster and corvette style MC. Booster is just about as far up as possible and the hanging pedal assembly from an late 70’s mid 80’s wrangler are all mounted. All this is left is connecting. But I am stuck with a 3:1 ratio on my brakes and obviously that’s not wanted... how could I fix this situation to make it more of a 5:1 or so ratio that I much more needed/safer. Without cutting our assembly and possibly ruining the cowl paint.
    Respectfully
    Biggs
     
  2. Feb 19, 2020
    BadGoat

    BadGoat How High Can You Climb?

    Northern Virginia
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    That's a tough change. My pedal assembly is bolted in, not welded. By using the complete YJ pedal and master assembly for power brakes, everything was already lined up. The immediate thought is you could use a pedal rod with an offset by either bending up a custom rod or welding an offset onto your existing rod. That would move the connection point up on the pedal assembly and help with the ratio. It would need to be strong as the rod takes a fair amount of force when you have to jump on the brakes. You wouldn't want it to bend or break at the worst time.

    Mike
     
  3. Feb 19, 2020
    47v6

    47v6 junk wrecker! 2023 Sponsor 2022 Sponsor

    USA
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    Wrangler YJ years are 86 to 95.

    If your pedal assembly is stock to a jeep with power brakes, then the ratio is fine as it was from the factory. The idea that you need more leverage for power brakes confuses me. If this pedal assembly and booster /master was designed to work together and in line, the master push rod and pedals should bolt up. Typically the mount for the master bolts to the back of the pedal assembly and sandwiches the firewall.

    I don't understand why you might need an offset rod or how that might affect your ratio unless the idea is to move the brake lever pin.

    How did you connect your clutch linkage or is this assembly one that has provision for a clutch master?

    Did you install this assembly or did you purchase this jeep with this in place?
     
  4. Feb 22, 2020
    Warloch

    Warloch Did you say Flattie??? Staff Member

    Falcon, CO
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    At this point I'd say we need some pics to be able to understand the situation, and possible help for you. I build my pedal setups as a 'system' where each is done with the parts its designed to work with and so I'm not sure I understand what your saying is the issue.
     
  5. Feb 22, 2020
    shaun

    shaun Member

    Lebanon, Ohio
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    My dual master is from summit and a corvette master so it’s more compact in size, the brake booster was from what terry mentioned to get an 8” boosters and the pedals are from an 80’s Jeep I can load pics but currently at work till Monday. So my set up is not all from same vehicle. My brake booster plunger sits about 3+in” down from pivot point on pedals and pedal length is about 13” long. Pivot point on pedals assembly are all the way up. I did not buy it this way, it was a 6w M38A1 with a few CJ parts like engine and dash. Following some of the threads on here it was mentioned to put the assembly as far up as possible to give more room for pedals and the 8” booster was mentioned to get for best fitment as well as operation.
     
  6. Feb 22, 2020
    Lockman

    Lockman OK.....Now I Get It . 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Silver Hill,...
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    Can you drill the pedal arm , 3 " down ? As long as the plunger goes into the booster straight, it should workout fine ?
     
  7. Feb 25, 2020
    shaun

    shaun Member

    Lebanon, Ohio
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  8. Feb 25, 2020
    shaun

    shaun Member

    Lebanon, Ohio
    Joined:
    Oct 15, 2015
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    390
  9. Feb 25, 2020
    shaun

    shaun Member

    Lebanon, Ohio
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    Pictures uploaded.. sorry for sideways pic.. so pedal measures About 14” and booster is about 5” down. Pivot point it at top.. this is my brake situation. Without having to cut out assembly and possibly ruin the paint any ideas how to get right ratio? Was thinking of fabricating a box to weld to assembly and re-drilling hold for hangin pedals to mount too.. but that’s a thought don’t even know if it would work..
     
  10. Feb 25, 2020
    Lockman

    Lockman OK.....Now I Get It . 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Silver Hill,...
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    5" down from where ? From your Pics ,I really think that you can move the plunger attachment point down by drilling the pedal arm. To test, attach the plunger , straight out to where it intersects at the pedal arm. You would want the hanging pedal arm , up & back , as far is it will go. Then just duct tape or zip tie to get an eyeball on it.
     
  11. Feb 25, 2020
    shaun

    shaun Member

    Lebanon, Ohio
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    5” down from pivot point on top of pedal don’t your normally measure from pivot point to bottom of pedal and then from pivot point to plunger on booster and divide them to get ratio?
     
  12. Feb 25, 2020
    Warloch

    Warloch Did you say Flattie??? Staff Member

    Falcon, CO
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    Pivot to Pedal Middle = X | Pivot to Push Rod Middle = Y Pedal Ratio = X/Y

    Calculating the Right Brake Pedal Ratio

    Based on what your saying - your push rod pivot needs to be about 3 1/2" down from pedal pivot and not the 5" you have.
     
  13. Feb 25, 2020
    shaun

    shaun Member

    Lebanon, Ohio
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    Correct. My dilemma is “ how do I lower the pedal assembly without ruining the paint. If I were to cut the assembly out, I’d have to weld it back in and may boil the paint job. Would fabricating a box to lower the pedals down to get better ratio work? Anyone have this issue before? “ the booster can not go up any higher either unless I modify the support bracket going from firewall to grille to give clearance for duel MC. This is only big thing stopping me right now from moving forward with build. After that I will be able to add fluids and hope to crank it up..
     
  14. Feb 26, 2020
    Warloch

    Warloch Did you say Flattie??? Staff Member

    Falcon, CO
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    Its gonna be a 8itch to do, but I would rebuild a box, attach to the bracket and drop the pedal assembly down to make the numbers work right.

    Getting that pedal assembly 'correct' is paramount to getting what you want in the brake setup. Take the time... Even think about bolt install with reinforced layers of metal as an option as well...

    Hate to say it, but it might be a good time to learn to do paint touch up :ninja:
     
  15. Feb 26, 2020
    shaun

    shaun Member

    Lebanon, Ohio
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    Yea I think we’re going to build a box maybe try to make something like AA has but a bit larger and attach it to the firewall. Try to get right ratio... may take a little bit of thinking and fabricating but keep the ideas flowing because I haven’t gotten to making anything yet... appreciate the ideas so far and sitting down with them to see what’s easiest
     
  16. Feb 26, 2020
    Warloch

    Warloch Did you say Flattie??? Staff Member

    Falcon, CO
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    I've got two of the AA Dual Pedal setups. One is in the Red '51 that I'm going to replace with Wilwood MC's in the next couple years. The other is on a tub I bought for a future build. They don't look that hard to fab, and what I'm going to base my own custom setup on for the Red '51. That way I won't have to do any firewall mods to get it to fit right like I did for the Wilwoods on the Blue '49.
     
  17. Feb 28, 2020
    duffer

    duffer Rodent Power

    Bozeman, MT
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    My take on this would be to just give it a try as is when you get the system hooked up and bled. If you don't have a vacuum pump to hook to the booster, you could just run a hose from another vehicle. With the booster, I don't think the pedal ratio is quite as important. More important is that the push rod travel on the dual circuit master cylinder is enough to bottom the piston before the pedal travel limit is reached. Otherwise you may not have enough travel to fully actuate the remaining circuit if you loose one.
     
  18. Feb 28, 2020
    Lockman

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    I agree...... Drill a new connection point on the existing pedal. get the plunger straight & you'll have plenty of " Ratio ".
     
  19. Feb 29, 2020
    shaun

    shaun Member

    Lebanon, Ohio
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    Good thoughts I do have a vacuum port. Can I go from the air filter port to the booster or off the “offy” 360 intake? Or does it matter..
     
  20. Feb 29, 2020
    duffer

    duffer Rodent Power

    Bozeman, MT
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    The manifold connection would be best as you should have more vacuum there.
     
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