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How long should front radius arms be?

Discussion in 'The Hokey Ass Message Board' started by jj mack, Oct 2, 2007.

  1. jj mack
    Joined: Mar 22, 2007
    Posts: 735

    jj mack
    Member

    Does it matter? Building from scratch and do not have any as reference.

    Is there rule of thumb out there for how long they should be?
     
  2. Appleseed
    Joined: Feb 21, 2005
    Posts: 1,053

    Appleseed
    Member

    I'd like to think that if you can make them structuraly sound, to put them as close to the steering arm to minimise bump steer. Assuming you're not using side steer. Get a second opinion though, cause I'm an idiot.
     
  3. GassersGarage
    Joined: Jul 1, 2007
    Posts: 4,727

    GassersGarage
    Member

    What kind of steering? Cross steer, drag link...?
     
  4. jj mack
    Joined: Mar 22, 2007
    Posts: 735

    jj mack
    Member


  5. With a drag link steering setup, the rear pivot for the front radius rods should be vertically aligned with the output shaft of the steering box. That way, as the front wheel travels up and down thru the range of the supension, the arc created by the swing of the draglink will be equal to the arc created by the radius rod, thus helping to eliminate bump steer.
     
  6. Rex Schimmer
    Joined: Nov 17, 2006
    Posts: 743

    Rex Schimmer
    Member
    from Fulton, CA

    I agree with brianangus, drag link and radius rod the same length. I have attached some pics of my lakes roadster to show how I did it.

    Rex
     

    Attached Files:

  7. GassersGarage
    Joined: Jul 1, 2007
    Posts: 4,727

    GassersGarage
    Member

    I agree, however, in some cases where the steering box is mounted on the frame in front of the cowl, an imaginary center line of the drag link should intersect the pivot point of the radius rod. The Oct issue of Rod and Custom has a great article on front ends.
     
  8. jj mack
    Joined: Mar 22, 2007
    Posts: 735

    jj mack
    Member

    Thanks guys. I agree with you 100%. But other than keeping the 2 equal length and parallel, what about the length of the 2.

    In theory they could be 2 feet or 4 feet.

    It seems to me the longer the better...you guys agree?
     
  9. KIRK!
    Joined: Feb 20, 2002
    Posts: 12,031

    KIRK!
    Member

    The longer the better. That way there is less arc in the travel of your front end.
     
  10. longer is always better....at least that's what my ex used to tell me.
     
  11. butch27
    Joined: Dec 10, 2004
    Posts: 2,847

    butch27
    Member

    That's what she told me when I took her out for the first time. LOL
     
  12. flathead31coupe
    Joined: Mar 23, 2006
    Posts: 1,596

    flathead31coupe
    Member
    from indpls, in

    back on the topic,i have always seen the front rods just about in the middle on the cowl, either on a coupe or a roadster,with my stock 46 rods they will be about 12'' toward the rear, than in the middle of the cowl,so longer is better.....i know that the older bones may be shorter thats just where they come out in the middle of the cowl...
     
  13. bobw
    Joined: Mar 24, 2006
    Posts: 2,376

    bobw
    Member

    Common aftermarket hairpin radius rods are 27" long. Add the clevis on one end and the tie rod end on the other end plus the spacing on the radius rod brackets and the total length is around 32-33". This is likely the shortest a builder would want to use.
     
  14. flathead31coupe
    Joined: Mar 23, 2006
    Posts: 1,596

    flathead31coupe
    Member
    from indpls, in

    so the earlier radius rods that i see on these coupes and roadsters that come to the middle of the cowl,are just the length that they came,they most likely didnt cut them to that lengh....if so mine should be ok longer.....
     
  15. flathead31coupe
    Joined: Mar 23, 2006
    Posts: 1,596

    flathead31coupe
    Member
    from indpls, in

    any thoughts on this?
     
  16. jj mack
    Joined: Mar 22, 2007
    Posts: 735

    jj mack
    Member

    I think you are right. I think they just split the wishbone, I believe there is weld there, and attach it with a splitting kit.
     
  17. fiat128
    Joined: Jun 26, 2006
    Posts: 1,426

    fiat128
    Member
    from El Paso TX

    Can you guys give some opinions on other the types of steering (with photos preferrably) as well?

    PS: Very good post, thanks.
     
  18. flathead31coupe
    Joined: Mar 23, 2006
    Posts: 1,596

    flathead31coupe
    Member
    from indpls, in

    so i should just leave mine longer, and not shorten it, i have yet to see a coupe or roadster with radius rods that go past the middle of the cowl....
     
  19. jj mack
    Joined: Mar 22, 2007
    Posts: 735

    jj mack
    Member

    Id leave em long, as long as your steering arm is in the right geometry (for cowl steer).

    I have seen them past the cowl before. I have seen a few where the front and the rear meet at the same point.
     
  20. flathead31coupe
    Joined: Mar 23, 2006
    Posts: 1,596

    flathead31coupe
    Member
    from indpls, in

    great thanks, iam using a 46 ford box mounted with the arm under the frame rail....
     

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