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Brake Caliper And Shock Absorber Collide

Discussion in 'Intermediate CJ-5/6/7/8' started by Craig1953, Dec 21, 2020.

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  1. Dec 21, 2020
    Craig1953

    Craig1953 Member

    Santa Barbara, CA
    Joined:
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    I could write an article about the challenges I have encountered in modifying both of my Jeeps, a1967 CJ5 and a1974 CJ5, by changing from front drum brakes to front disc brakes. The information that I found on EarlyCJ5.net, and the advice from other members has been invaluable. I am almost done. The systems work fine and on the road the disc brakes makes stopping, especially in a “panic brake” situation, much more comfortable. But I mostly like to use the Jeeps on 4WD trails, there I discovered an issue that can create a really dangerous situation.

    I left the 74 with a mechanic who did the conversion for me. He told me everything was fine. It wasn’t. One easily fixed problem was that the disc brakes were not “releasing”, making me think it was a stuck caliper. I came to discover that he had plumbed the balancing valve backwards. The line that was supposed to go to the front brake input port on the balancing valve was connected to the input port for the rear brakes, and vice versa. I switched them to their correct positions and that problem was solved.

    I didn’t find out about another much more serious problem until we were on a 4WD trail in the Panamint Mountains near Death Valley. I would have known about the issue if I had done the modification myself, but I didn’t. I just trusted that, except for the backwards plumbing, the mechanic knew more than I did about this sort of thing.

    Here’s what happened: When going up a steep rocky section I had to make a sharp left turn at the same time as the left front wheel was dropping off of a big rock. The next time I hit the brakes, the pedal was “spongy”, but still stopped the Jeep. (a benefit of having a 2-line brake system is that if one system fails, the other will still work, although marginally) Upon investigation I found that on the hard left turn the metal ferrule that attaches the brake hose to the “banjo bolt” fitting at the caliper had collided with the shock absorber. The result was that it punctured a hole in the shock tube and bent the “banjo bolt”, thereby draining the brake fluid from the front brakes. Now, I don’t usually carry spare “banjo bolts”, so there was no in-the-field repair to be done. Fortunately, we were able to make it home on the rear brakes alone. If the failure had happened at a more dangerous part of the trail it could have been a disaster. I think that I could have driven around on pavement for many months without knowing about the problem. I was only in that situation, i.e. a hard left turn and a sharp bump, that the hazard appeared. It’s like not knowing that a rattlesnake is living under your front step, until you reach under there to retrieve something that fell through the cracks.

    So, now to get to the point. I have to figure out what to do to remedy the situation. I think there are two things I should do to keep this from happening again: 1, Besides the problem with the brake caliper, the shocks also bang up against the axle tube, so I need to get smaller diameter shocks which should help with both problems, and 2, I need to figure out how to move the bottom mounting point for the shocks toward the rear of the vehicle by about 1 to 1-1/2 inches.

    So here is my question: It seems like The easiest way to move the bottom shock mounting point would be to find a replacement U-Bolt Tie Plate (see attached diagram) that already has the shock mount farther back, or to get a welder to modify the existing Tie Plate so that the shock mount is farther back. Do any of you know if a U-Bolt Tie Plate with a “more distant” shock mount is readily available? Or should I have them fabricated? Or another solution?

    Here's a link to a video that shows the problem:




    Caliper meets Shock.jpg

    Punctured Shock.JPG

    Shock hits axle.JPG

    U Bolt Tie Plate.JPG
     

    Attached Files:

  2. Dec 21, 2020
    bigjohn

    bigjohn Active Member

    Kelso Wa
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    Could be fixed simply by installing smaller tube shocks like bilstien or fox. You could also look into changing to f250 shock towers enabling use of longer travel shocks and moving the upper shock mounts. That still seems like it would be very close though.
     
  3. Dec 21, 2020
    Fireball

    Fireball Well-Known Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Pullman, WA
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    It also looks like rotating the hose so it points straight up off the caliper would work too, but you would need some way to keep it from rotating and unscrewing itself since the cast bumps are in the wrong place for that.
     
  4. Dec 21, 2020
    45es

    45es Active Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Naches, WA
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    If you look at your attached view of the spring / shock assembly, you will notice the that shock is mounted in front of the axle. Doing this should fix your issue.
     
  5. Dec 22, 2020
    zila

    zila I throw poop

    Rock Springs,...
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    On my 75 CJ there is a turn limiting bolt. Maybe yours is missing or needs adjustment.
     
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  6. Dec 22, 2020
    52M38-73CJ5

    52M38-73CJ5 Member

    Wenatchee WA
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    What conversion kit did you buy to convert to disk. I narrowed a Scout 44 to narrow track and have seen no problems.
     
  7. Dec 23, 2020
    Craig1953

    Craig1953 Member

    Santa Barbara, CA
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    Thank you everyone for your input. As usual, the simple solution is the best solution. I am getting new shocks that have a smaller diameter thanks BigJohn), and adjusting the stops on the steering (thanks Zilla). That should do it!
     
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  8. Dec 23, 2020
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    If you used drum brake knuckles and stock disc brake caliper brackets then the calipers/brackets are clocked incorrectly. The calipers should be clocked upward 1/2 the distance of the drum brake bolt pattern and disc brake caliper brackets. I cannot tell if this is the case from your pics. Yes this seemingly small amount makes that much of a difference.
     
  9. Dec 24, 2020
    Mr Vaughan

    Mr Vaughan

    if you move the shocks to the front of the axle like 45es mentioned, it would entirely erase your issue. not sure if the frame shock mount would work, but it would be fairly simple to make it work.
     
  10. Dec 24, 2020
    Mr Vaughan

    Mr Vaughan

    also, while we are on the topic of suspension, can we talk about springs? i've noticed that some jeeps have 10 leaf fronts, and others have 5, and yet others have 7. are they interchangeable?:shrug:
     
  11. Dec 24, 2020
    sterlclan

    sterlclan Member 2022 Sponsor

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    As long as the length and center pin are the same they will fit all are different rates and need to be used In pairs
     
  12. Dec 25, 2020
    Craig1953

    Craig1953 Member

    Santa Barbara, CA
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    Hi Nickmil, I get the idea of "clocking", but I don't understand, "The calipers should be clocked upward 1/2 the distance of the drum brake bolt pattern and disc brake caliper brackets." The bleed nipple is straight up-and-down vertical. Does that sound right?

    45es and Tyler, I am sure that the shock mount location in back of the front axle is correct for this 74 CJ with the inline 6. I can't see any way it would be right to try to locate it in front of the axle.

    Merry Christmas to All
     
  13. Dec 26, 2020
    RATTYFLATTY

    RATTYFLATTY I think you need a little more throttle

    Central MN
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    Moving the shock to the front side of the axle is better than the rear but you will still have clearance issues with the tie rod unless you run a shock that you can have the body up. There could be some contact at full compression when fully turned left or right. Here is my rendition, my fenders are by no means great so cutting them didn't bother me.
    resize1.PNG


    resize 1.JPG
     
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  14. Dec 26, 2020
    Keys5a

    Keys5a Sponsor

    Florida Keys
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    The clocking Nick is referring to is where the caliper bracket bolts to the knuckle. There are six bolts. The knuckle you have is intended for a drum backing plate. The later D30 axle that came with disc brakes has a different knuckle where those six bolt holes are rotated, or "clocked" differently. Aftermarket caliper brakets can account for this difference, but stock caliper brackets, though they bolt on, can put the caliper in the wrong location, as you found out.
    To complicate this even further, there are two different factory disc brake setups on the CJ5 D30, depending on the years.
    -Donny
     
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  15. Dec 26, 2020
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    So, Nick or Donny, what's the usual best way to deal with this: redrill the knuckle, redrill the bracket, or buy aftermarket brackets? Or find disk brake knuckles from a 30?
     
  16. Dec 26, 2020
    Craig1953

    Craig1953 Member

    Santa Barbara, CA
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    Re: “unless you run a shock that you can have the body up”
    In general, and not having to do with this specific application, if the shock fits does it make any difference if it’s mounted body up or body down? I suppose if you developed a leak where the rod enters the body it would be messier if it was mounted body up?
     
  17. Dec 26, 2020
    Craig1953

    Craig1953 Member

    Santa Barbara, CA
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    Yes, I understand. But is there a “correct” clock position? Or is it just, rotate it to the position where you have the least interference? I thought it best to keep the bleed nipple in the highest position to better bleed the air out of the system.
     
  18. Dec 26, 2020
    Craig1953

    Craig1953 Member

    Santa Barbara, CA
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    Thanks for the pics! It makes it so much easier for me to see what’s involved with relocating the shock forward of the axle. I think I would rather leave the shock where it is, but maybe turn it upside down, and adjust the turn limit bolt to prevent the caliper from contacting the shock. But adjusting the limits may mean having to accept having a bigger turning radius. I guess I won’t know until I try it.
     
  19. Dec 26, 2020
    SFaulken

    SFaulken Active Member

    Bellevue, WA
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    Not all shocks are able to be mounted with the body up. Especially cheaper non-monotube styles, they almost literally won't work, if you mount them upside down, either they will lock up and you might as well rigid mount the axle, or they'll provide no damping at all, because they aren't designed to operate that way.
     
  20. Dec 26, 2020
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    Easiest way is to redrill the bracket. Aftermarket brackets like the gold cad plated ones are already drilled for both patterns. You can use a spindle as a layout tool to redrill stock brackets. This is for the GM 1/2 ton style brackets.
     
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