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Will tires rub with split bones on a 1940 axle??

Discussion in 'The Hokey Ass Message Board' started by scrap metal 48, Jul 29, 2012.

  1. scrap metal 48
    Joined: Sep 6, 2009
    Posts: 6,075

    scrap metal 48
    Member

    Will I get enough turning radius with this set up?? It will be on a model A and have 40 brakes and 4.50x16" tires on 4 1/2" wide rims... Thanks in advance....
     
    Last edited: Jan 16, 2014
  2. onekoolkat1950
    Joined: Mar 23, 2008
    Posts: 1,865

    onekoolkat1950
    Member

    i'm running a dropped 40 axle with a reversed eye model a spring and split bones.i had to mount the radius rod brackets to the inside of the frame to get the turning to go to full lock.to run spring on top you will have to make your own shackles on inch wider than factory.
     
  3. scrap metal 48
    Joined: Sep 6, 2009
    Posts: 6,075

    scrap metal 48
    Member

    Anybody else run this combination...
     
  4. scrap metal 48
    Joined: Sep 6, 2009
    Posts: 6,075

    scrap metal 48
    Member

    I changed the title cause wasn't getting any responses.. I'm sure someone has run this combo.. I know the perch bolt holes are farther apart than say an aftermarket axle and wondering if there is enough turning radius with this setup...
     

  5. Tim
    Joined: Mar 2, 2001
    Posts: 12,801

    Tim
    Member
    from KCMO

    There basically going to tell you what he just told you.

    They are mounted further apart on the axel so if you split them you can run them just not to the standard frame rail point.

    I think he hit all the points already?


    Posted using the Full Custom H.A.M.B. App!
     
  6. RustyNCA
    Joined: Feb 18, 2009
    Posts: 406

    RustyNCA
    Member

    Well, I am running a stock 40 Ford axle and brakes except I have 6.50x16 tires on 35 wires, and I get enough turning radius out of it, but I do rub the tires on the bones. If it's relevant, I also am running the center link tie rod up front, which gives me incorrect ackerman, which I think adds to the rub issue.
     
  7. hotrod40coupe
    Joined: Apr 8, 2007
    Posts: 2,562

    hotrod40coupe
    Member

    The closer you place the mounting point to the centerline of the car, the better the ride will be. That will also eliminate any rubbing issues. Check out the setup from Chassis Engineering.
     
  8. Dizzie
    Joined: Feb 7, 2012
    Posts: 245

    Dizzie
    Member

    I have a '40 axle in my current '34 pickup project. I am running 6:50 front tires, and yes I did rub on full turn. I added just enough metal to the stop on the king pin lock and it solved the problem. A friend had same problem on his model A and used same cure.
     
  9. Yes, and it turns about as tight as a 4x4 crew cab long bed dually pic up. You'll have a hard time holding your lane in a right turn unless you bend them or mount them inside the frame
     
  10. DICK SPADARO
    Joined: Jun 6, 2005
    Posts: 1,887

    DICK SPADARO
    Member Emeritus

    Your turning radius will be controlled by the steering box throw, the steering arm ratio, any obstruction to the tire radius and lastly by the wheel base. Assuming you have a normal steering box and stock style steering arms that issue is solved. Next is the tire obstruction. In most cases there is some kind of chassis linkage at the perch mount, ie: wishbones , 4 bars, hair pins, The position of these is controlled by the perch pin span on the axle and to the axle spindle boss reference to the perch pin boss. The perch span differs as to axle design as well as the axle perch boss to spindle spacing especially if you are using an original custom dropped axle.

    The easiest way to determine interference is to mock up a set up on paper. indicating the perch boss and the spindle center point and then determine the radius of the tire you are running. By using the tire radius as a clearance distance, swing a measurement point from the vertical spindle boss center equal to the radius of the tire measurement and it will indicate the radius that your wheel assembly will rotate before it hits an interference point. That will indicate the turning radius angle you can achieve. If you need to increase the angle you will have to move the obstruction point.
     
  11. scrap metal 48
    Joined: Sep 6, 2009
    Posts: 6,075

    scrap metal 48
    Member

    Thanks Dick, I think...
     
    Last edited: Jan 17, 2014
  12. RustyNCA
    Joined: Feb 18, 2009
    Posts: 406

    RustyNCA
    Member

    I haven't experienced that problem, just that on dirt or gravel parking lot at low speed, it will push the front end a bit.

    Driving it at speed I have not had any issues with the setup.
     
  13. This is a great explanation Dick!!!
    But I just look at it differently:
    The biggest problem ( obstruction) will show up (limit) first.
    If the tires hit the bones before the rest has a chance to reach its full potential the fat lady has finished singing.



     

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