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Hot Rods Help: Forward steering Ackerman issue.

Discussion in 'The Hokey Ass Message Board' started by Watto's 65, Dec 19, 2022.

  1. Watto's 65
    Joined: Jun 18, 2022
    Posts: 27

    Watto's 65
    Member
    from Tucson,AZ

    With my current build (29 Model A Pickup), I had to go with forward steering. The steering arms were swap meet find and at some point, someone dropped them.
    After flipping them, I had to heat and bend them closer to the rotors. But the issue I'm having now is, at full lock, left or right, the outside wheel has a greater turn than the inside.
    This is the first time I'm used forward steering, so I wanted to ask if this is common?
    New spindles, K-Pins, bearings, spacers, tie rod ends, axle is straight, etc.
    Thanks for any input! Will post photos later tonight.
    Watto
     
  2. manyolcars
    Joined: Mar 30, 2001
    Posts: 9,609

    manyolcars

    sounds like you need to adjust the drag link
     
  3. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 6,063

    2OLD2FAST
    Member
    from illinois

    The outside turning radius should be greater than the inside .
     

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  4. '29 Gizmo
    Joined: Nov 6, 2022
    Posts: 1,197

    '29 Gizmo
    Member
    from UK

    If the steering link is in in front of the axle the ball joints need to be further outboard than kingpin. You need a line from the ball joint through the kingpin to the centre of the rear axle
     
  5. squirrel
    Joined: Sep 23, 2004
    Posts: 60,072

    squirrel
    Member

    no pictures? how will we ever figure out what you have, without pictures?

    Anyways...

    [​IMG]
     
  6. alchemy
    Joined: Sep 27, 2002
    Posts: 22,818

    alchemy
    Member

    Replace the words "tie rod end" everywhere he said "ball joint". Then look at Squirrel's diagram and you will see what needs to be done.
     
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  7. Happydaze
    Joined: Aug 21, 2009
    Posts: 2,400

    Happydaze
    ALLIANCE MEMBER

    Whats already been said, plus, as a rough guide, to make this work the tie rod ends typically need to be perilously close to the brake disc. Need pics.

    Chris
     
  8. Watto's 65
    Joined: Jun 18, 2022
    Posts: 27

    Watto's 65
    Member
    from Tucson,AZ

    I could'n get a full photo from above, so spliced together. Screen Shot 2022-12-19 at 11.04.53 AM.png Screen Shot 2022-12-19 at 11.04.16 AM.png Screen Shot 2022-12-19 at 11.03.11 AM.png Screen Shot 2022-12-19 at 11.03.07 AM.png Screen Shot 2022-12-19 at 11.03.00 AM.png Screen Shot 2022-12-19 at 11.02.55 AM.png
     
    Last edited by a moderator: Dec 19, 2022
  9. Johnny Gee
    Joined: Dec 3, 2009
    Posts: 14,447

    Johnny Gee
    Member
    from Downey, Ca

    Photos with out wheels and tires would be nice so we could see the steering arms also.
     
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  10. Happydaze
    Joined: Aug 21, 2009
    Posts: 2,400

    Happydaze
    ALLIANCE MEMBER

    Overhead pic with no wheel and heading straight is whats required.

    Chris
     
    X38 likes this.
  11. Pete Eastwood
    Joined: Jul 27, 2011
    Posts: 1,333

    Pete Eastwood
    Member
    from california

    You will never get the correct "ackerman" with your setup.
    You will just have to live with what you have.
    When cornering one wheel will "push".
    For the "ackerman" to be correct, the tie rod end would have to be on the other side of the rotor!
     
  12. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 6,063

    2OLD2FAST
    Member
    from illinois

  13. gimpyshotrods
    Joined: May 20, 2009
    Posts: 24,563

    gimpyshotrods
    ALLIANCE MEMBER

    I came here to say this, too.

    This can only be fixed one way. The right way.
     
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  14. gimpyshotrods
    Joined: May 20, 2009
    Posts: 24,563

    gimpyshotrods
    ALLIANCE MEMBER

    Common? Yes. Common, and wrong.

    This cannot be fixed the way you are going. You need deeper drop steering arms, and to put the tie rod behind the axle, where it belongs.
     
  15. nobby
    Joined: Jan 8, 2006
    Posts: 1,358

    nobby
    Member

    from the spindle face of a 37-40 spindle , where the indent is to receive the brake back plate bolt
    the measurements are nice round numbers
    the steering arm length is 5'' and it comes over 2''

    its about that, so as to give you angle of 15 and 75 degrees
    if the hypotensqueeze is about 7.3
    so you can almost correct your own homework by
    halving the king pin to king pin distance of 48
    =24
    and the wheel base being 112
    its close enough at 12 and 78 degrees
    BUT I bet they shot for nice round numbers originally
    I would wager that IF you did the same for a 30 model spindle at
    50.5 in half 25 and 104
    its like 14 and 76

    something like that

    BUT when you then fit a 46'' king pin to king pin axle
    and fit it to a 104 inch wheel base
    its 12.5 and 77.5
    i bet its supposed to be 78
     
    Last edited: Dec 19, 2022
  16. jimmy six
    Joined: Mar 21, 2006
    Posts: 17,218

    jimmy six
    ALLIANCE MEMBER

    Wattos 65…They way I read what I think your saying is it’s doing just as it’s supposed to. . . . . If your Ackerman is close…

    When you turn to the left… the left tire/wheel will make a tighter circle than your right tire/wheel.

    If you turn right…the right tire/wheel will make a tighter circle than your left tire/wheel.

    I have needed to have the tie rod in front before and bent out the arms as close as I could to the rotors or backing plates. A stated above … a line drawn from each side should cross over the third member whether the tie rod is in front or behind the axle….
     
    Last edited: Dec 19, 2022
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  17. 38Chevy454
    Joined: Oct 19, 2001
    Posts: 6,816

    38Chevy454
    ALLIANCE MEMBER

    It's been identified that you need to move the tie rod ends out further. Study the diagram that Squirrel posted, and make your car to be as close to that as you can.
     
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  18. Mimilan
    Joined: Jun 13, 2019
    Posts: 1,255

    Mimilan
    Member

    If you can't bend the steering arms outward for increased ackermann, then bend them upwards.
    This increases ackermann due to kingpin inclination
    This is also one of the reasons why "front steer" 4x4's have raised tie-rods.
     
    Last edited: Dec 19, 2022
  19. Moriarity
    Joined: Apr 11, 2001
    Posts: 38,060

    Moriarity
    SUPER MODERATOR
    Staff Member

    is there a good reason why the tie rod needs to be out front? there is a reason why they are behind on almost all old fords. Because that is what works.
     
  20. Mr48chev
    Joined: Dec 28, 2007
    Posts: 36,061

    Mr48chev
    ALLIANCE MEMBER

    This PFD uses The algebra formulas that I never got a grasp on back in school. On the other hand it actually explains Ackerman principle or "Davis" principle as it applies to rigs with the tie rod in front of the axle. IRJET-V6I4302.pdf

    The gist of it from the drawing in this screen shot of the pfd is that your theorietic tringle is flipped and the center will be the distance of the wheel base out in front of the car.

    Done correctly the wheels are not going to be turning at the same angle on a turn. they will carry an angle so that the outer wheel follows a perfect but larger circle that is centered on the circle the inner wheel takes that in turn is centered on the extended line from the rear axle where both lines from the front wheels intersect that line at the same spot.
    If the Ackerman is off one of the front tires is going to try to push or drag the other one out of it's circle. If you have ever watched a front engine digger with an Angla front axle or Angela spindles and steering arms try to turn one tire is always dragging the other on turns and that is a true demonstration of Ackerman principle not being applied. Screenshot (775).png
     
  21. blue 49
    Joined: Dec 24, 2006
    Posts: 2,148

    blue 49
    Member
    from Iowa

    I also have front pointed steering arms on my Henry J (flat plate ones from Speedway). They are made with rear steer Ackerman built in so they were terrible as is. I left black marks on my driveway from tire scrub when backing out on my street. It drove fine in a straight line. I did what you did and it really helped. No more noticeable scrub in tight turns. I know it's not perfect, but it isn't going to affect how it drives in 95% of your driving.

    Gary
     
  22. Marty Strode
    Joined: Apr 28, 2011
    Posts: 9,717

    Marty Strode
    Member

    I built this T back in 78, we got it as close as we could, and it drove great. You could notice a little scrub, on a tight turn in a parking lot. It was a Touring with a 104" WB. img20161231_15371815.jpg img20161231_15383577.jpg
     

    Attached Files:

  23. Mimilan
    Joined: Jun 13, 2019
    Posts: 1,255

    Mimilan
    Member

    Old British Fords have the tie-rods in front (Anglias and Prefects)
     
  24. Moriarity
    Joined: Apr 11, 2001
    Posts: 38,060

    Moriarity
    SUPER MODERATOR
    Staff Member

    they were engineered that way at the factory, Old fords came with the tie rods in the rear. There must be a real good reason that most people go through the effort to keep them on the rear where they belong
     
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  25. AccurateMike
    Joined: Sep 14, 2020
    Posts: 801

    AccurateMike
    Member

    I have a couple. I don't think so.
    angliae93a.gif
    Mike
     
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  26. Looks to me that your total ch***is is hand built. So you built it for the Tie Rod to be out front. Couple options, live with it the way it is or make some changes. Some choices just aren't as good as others. We learn by making mistakes much better than just being told it's not a good idea. Been there done that!
     
  27. NasT
    Joined: Aug 8, 2008
    Posts: 189

    NasT
    Member
    from MD

    I’ve been through this before. It has to look like this or it won’t work at all.

    I personally like the look but the arms need to be very close to the rotors. It has to hit these 3 points in a straight line.

    center rear axle
    Kingpin center
    Tie rod

    22D97C28-177E-4B09-BD22-83E8F540D0A2.jpeg B67FF274-4B88-4103-AB68-01FE379B8C13.jpeg
     
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  28. blue 49
    Joined: Dec 24, 2006
    Posts: 2,148

    blue 49
    Member
    from Iowa

    In my case, the tie rod ends interfered with my calipers when I went to bigger rotors. I've since made new caliper brackets that rotate the caliper up so they might clear now, but I don't see a reason to try it. Also, more ground clearance in the front.

    Gary
     
  29. Fuzzy Knight
    Joined: Jun 8, 2009
    Posts: 11,806

    Fuzzy Knight
    Member
    from Santee, Ca

    This is the way it MUST be done!!!!
     
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  30. deucemac
    Joined: Aug 31, 2008
    Posts: 1,654

    deucemac
    Member

    Rudolph Akerman discovered his principle in the 1700s on wagons. In order to turn either direction, the wheels need to move in 4 separate arcs. Because the rear axle wheels are not connected to each other they will find their own arcs and speeds. Modern differentials allow the same thing. Up front, the wheels are tied together through a tie rod, or in the case of an independent front end, a center link (drag link) and equal length tie rods joined to steering arms. Several posts have shown the angles needed for proper "toe-out" on turns. Steering arms MUST follow a line drawn from the centerline of the rear axle, projected the steering axis or king pin fulcrum. If the arms are behind the axle they must point in towards the rear axle centerline on the projected line drawn. If they are pointing forward, they must point out on the same projected line. If not, the outer tire and the inner tire cannot turn on the proper radius. I remember an argument with another front end man that Akerman didn't matter. We had access to a 65 Impala that had the arms facing forward but inward. I made a couple of tight circles and you could see the rubber that peeled off because the outer tire had a tighter turning radius that the inner tire. Foolish engineers trying to get the engine lower in the ch***is and and not extent the tread width outward to compensate for proper clearance for arms bent outward along that line, have caused unnecessary tire wear in the name of styling. Principles are fact not suggestions, or nice things to do if easy. Years ago, when I raced sprint cars, our steering arms were designed to have no Ackerman built in, but to point straight back instead. Years earlier, racers found out that if Ackerman was left in p***enger car steering arms adapted to race cars, that when the cars would corner and bounce around through the ruts, that is one front tire came off the ground that the car would dart in the direction of the wheel and tire still on the ground and just as soon as the other wheel and tire bounced off the ground, the car would dart in the direction of the tire on the ground. That created quite a handful on a rough track! I am sorry for the long winded explanation. So many people feel that if they set the toe to factory specs, Ackerman will be okay. Fact is that Ackerman is designed in an can't be adjusted. Only by bending the steering arms to comply with the Ackerman projected line can it be corrected, if there is room.
     
    X-cpe, Fordors, alchemy and 2 others like this.

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