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Technical rear radius rod brackets ,witch one?

Discussion in 'Traditional Hot Rods' started by 410merc, Mar 3, 2016.

  1. 410merc
    Joined: Mar 31, 2014
    Posts: 69

    410merc
    Member

    hello everyone , lately i'v been looking at rear radius rod brackets ,and now I'm confused , I'm building a modal a tudor{30} I will be using the stock modal a frame boxed of course with a k brace ,and I'm also using a 9 inch ford rearend with the stock modal a spring I did however remove 2 leaves ,and I want to use hairpin radius rods I like there looks ,so heres my question I was once told to have the top radius rod even with the top of the axle tube if I do this it seems like I will have to have a long bracket otherwise it will run at a upward angle from the axle to the frame bracket and look funny doe anyone have pics or advise
     
  2. I make my own.
    These are For ladder bars but kind of the same problem.

    image.jpg

    image.jpg

    On a flat A frame you need to move the frame bracket attaching point down, yes it's longer.
     
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  3. 410merc
    Joined: Mar 31, 2014
    Posts: 69

    410merc
    Member

    should the top of the bar run square with the frame ,
     
  4. 410merc
    Joined: Mar 31, 2014
    Posts: 69

    410merc
    Member

    I see speedway motors has one called thelow rearaxle bracket part no916-45009 I would think one like that it looks like anything else would maybe interfere with the spring travel correct ?
     

  5. How about you post a picture of what stance and ride height you're after along with the amount of power you'll be putting thru it.

    Those brackets are great for channeled cars because it gets the bars below the floor pan. They also work well for a chassis with rear sweep or a Z frame.

    A Stock model A just rides high,
    No matter what you do the frame bracket is long and below the frame or the bars go uphill.

    See the bars and ride height ?
    Let's say that rear tire is at least 28", fair to say it's more though. That means there's about 14" to the ground under that frame
    image.jpg
     
    Last edited: Mar 3, 2016
    410merc likes this.
  6. tubman
    Joined: May 16, 2007
    Posts: 5,590

    tubman
    ALLIANCE MEMBER

    31Vicky,

    I can't see the front mounting of of the hairpins, but if it is what I think it is, you will have a problem with the suspension binding with the setup you have. Ford originally had a singular mount in the front (the ball on the front of the torque tube) that would allow each wheel to move up and down independently. Your setup (as I see it) will restrict this independent movement, resulting is suspension failure down the road. I learned this the hard way in the '60's with my first "T"-bucket build. After a few hundred miles, one of the side members (your hairpins) broke right behind the tie rod end I used as a pivot.

    I may be all wet here since I can't see the front mount, but it's food for thought.
     
  7. These are for Ladder bars
    image.jpg
     
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  8. 410merc
    Joined: Mar 31, 2014
    Posts: 69

    410merc
    Member

    what would you guys recommend , I don't want to z my frame
     
  9. Drop the frame bracket some and let the bars go up hill a bit. Split the difference.
     
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  10. 410merc
    Joined: Mar 31, 2014
    Posts: 69

    410merc
    Member

    now that sounds like a great idea
     
  11. tfeverfred
    Joined: Nov 11, 2006
    Posts: 15,792

    tfeverfred
    Member

    Knowledge..........HAMB
     
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  12. Andy
    Joined: Nov 17, 2002
    Posts: 4,719

    Andy
    Member

    If the pivot point is way higher than the axle, you may get some funny rear steer on bumps. The reason is the rear moves in an arc and will move forward and back if the pivot is not near the axle height.
     
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  13. DDDenny
    Joined: Feb 6, 2015
    Posts: 14,768

    DDDenny
    Member
    from oregon

    Whatever you do, don't let anyone talk you into using those HIDEOUS looking four bars that, for the life of me can't understand the widespread use on the Model A builds, especially hiboy A's. I'd include a photo but I don't want to corrupt this thread.
    A badly designed ladder bar design would please me more than the best four bar setup.
    Not that you need to please me, but those are FUGLY.
    Rant over.
     
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  14. 410merc
    Joined: Mar 31, 2014
    Posts: 69

    410merc
    Member

    I see your go uphill a little also unless I'm not seeing right , i'll be using a smalblock chevy fairly stock
     
  15. 410merc
    Joined: Mar 31, 2014
    Posts: 69

    410merc
    Member

    would there be anything wrong with making my axle bracket so the top bar just sets a little higher then the axle
     
  16. Andy
    Joined: Nov 17, 2002
    Posts: 4,719

    Andy
    Member

    You can move the rear attachment up if you want, The angles of the bars do not change the suspension geometry, Just the axle relative to the pivot counts. You could replace the hairpins with radius rods and it would act the same. Make whatever clears, looks good , and is pivoted together near the center of the car.
     
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  17. 410merc
    Joined: Mar 31, 2014
    Posts: 69

    410merc
    Member

    so then the top bar does not have to be even with the top of the axle tube
     
  18. 410merc
    Joined: Mar 31, 2014
    Posts: 69

    410merc
    Member

    perfect could I make them so there a little further away from the axle tube so the spring don't hit it if yaa hit a bump on the road
     
  19. So- with a preference= the rubber mounted bushings in the front or the bars, or heim's, for some adjustability? only asking because I'm going to have to do this soon. never had an issue with heim end's, and de-bunking the myth's that their shitty...... possibly with a aftermarket,or non rubber bushing would suffice, but,seek real world tried and true feedback,and not the 1-800# that "that's what they came with" and they "seem" fine....
    Just because the street roddy crowd is cool with the part's,doesn't mean they can use a lil help........
    I'm not digging a rubber bushing to wear out if you follow me...... Thoughts/experience please-
    Thanks-Kid
     
  20. The rubber bushings are more along the lines of polyurethane but not like the super hard stuff. They do wear eventually, such as like brake pads will.

    There's some cushion and compliance in the bushing that makes sense but the number one thing is double shear bracket and thru bolt.
    There's a bit of adjustment at the rear but it's a pain and its minimal so you need to be close in square, wheel base and pinion angle.

    A heim joint would work equally well but be a bit harsher,
     
  21. Thanks- I just come from the school of total adjustability= tire size/pinion angle......=changes in time if there's a need. Don't want to melt things in , and be stuck. And of course a double shear. Even though overkill, a double adjustable ladder...... might be a bit long in length, but once your trapped in adjustment,I figured/figure, you're screwed. Just got to have a ways out even if engineering looks good on paper.......Familiar with the set up, and how to.......just not with bushings. I can live with a lil harshness, but have done it before and didn't notice things, so a new world with an A, vs an all out drag car driven as a daily driver.....The unknow is what makes me ponder.........
    .Thanks!
     
    Last edited: Mar 13, 2016
  22. Blue One
    Joined: Feb 6, 2010
    Posts: 11,021

    Blue One
    ALLIANCE MEMBER
    from Alberta

    Wow, witches have leaf springs on their brooms and radius rod brackets too :D:D:D
     
  23. I don't know if this will paint a picture for you but these are the brackets that 31Vicky posted. I know my frame has a 7 inch kick up but this is how it looks and the spring is behind the axle. 100_1255.jpg
     
  24. rbaumgar
    Joined: Oct 3, 2019
    Posts: 5

    rbaumgar

    Hi Swade41, your rear bars are the exact design I've been looking for!!!! Did you buy them, make them yourself?
     
  25. dumprat
    Joined: Dec 27, 2006
    Posts: 3,050

    dumprat
    ALLIANCE MEMBER
    from b.c.

    I personally am a big fan of rubber bushings at the axle end and heims at the frame. It works well and doesn't tend to break or bind up as the rubber will flex a little.

    An easy way to decide on a link placket location is with string. (Unless you can get a copy of the online link locater software)

    With a couple pieces of string.
    From the centreline of the rear axle tube at the point you want to attach the bracket, through the center of the front axle in the middle will give you a pretty good idea of the VERTICAL location of the frame mounts correct position.
    The horizontal is the closest to a triangle you can achieve.
    This design is what you use for a three link or ladder bar with a panhard. There are thousands off off-road suspension designs that use this principle.
     
  26. Andy
    Joined: Nov 17, 2002
    Posts: 4,719

    Andy
    Member

    I have used the single torqe arm for 55 years on everything I have built. It works extreamly well It balances all the loads and has no binding.
    frame 3.jpg
     

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