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Technical Panhard on model a

Discussion in 'The Hokey Ass Message Board' started by BC Texas, Oct 20, 2015.

  1. BC Texas
    Joined: Mar 14, 2011
    Posts: 32

    BC Texas
    Member
    from Arp. Texas

    Chopped 29 special coupe
     
  2. BC Texas
    Joined: Mar 14, 2011
    Posts: 32

    BC Texas
    Member
    from Arp. Texas

    First time on this one and messed up already.
    Building full gendered 29 chopped top special coupe. It has 283/700r4 with a half rack and pinion steering. Superbell 4" dropped front axle. Split wishbones out to the frame, (boxed model a).
    Question is, will it still need a panhard bar? Some say yes, some say no.
    What do y'all think?
    BC Texas
     
  3. Atwater Mike
    Joined: May 31, 2002
    Posts: 10,428

    Atwater Mike
    ALLIANCE MEMBER

    Dead perch. ('tethered' right hand shackle) Do a search...
     
  4. My take is Henry never used one until he went to loose rubber shackles etc in '42. Personally I've have never found the need for one on any of the cars we built. I've always used wishbones or hairpins; but maybe the four bar fronts are softer and need the side to side control, the guys that make the four bars are the guys that started selling the panhard bars. Just my take on this subject; like you said there others will have an equally strong belief in the need for a panhard bar.
     
    scrap metal 48 likes this.

  5. Probably not necessary with a half a rack.
     
  6. Jimmy2car
    Joined: Nov 26, 2003
    Posts: 1,707

    Jimmy2car
    Member
    from No. Cal

  7. A properly pre loaded over axle spring will keep it centered.
     
  8. flamedabone
    Joined: Aug 3, 2001
    Posts: 4,887

    flamedabone
    ALLIANCE MEMBER

    Any cross steer arrangement will need a panhard bar or dead perch. When you steer, the steering rod pushes or pulls the front suspension to the left or right on the axis of the perches. If you don't have a panhard bar, you can actually watch the frame rock to the left or right when you steer. It is not a whole lot, but definitely enough to make a difference.

    Also, sell that gay ass half rack to some street rodder and get a proper steering box.

    Good luck, -Abone.
     
  9. BC Texas
    Joined: Mar 14, 2011
    Posts: 32

    BC Texas
    Member
    from Arp. Texas

    I have tried a 47 Ford pickup steering box. It needed a panhard bar. I bout this rack cheep so I guess I will try it and see. I also have a reversed corvair and vega box. Already installed the rack using Vega mounting plate so if its not satisfactory will try the Vega. My friend has a Vega box that we put on his Vicky and it does well. I'm looking for less turn from stop to stop. Vega has less than 47 Ford. Rack is supposed to be less than that without losing the easyness of it. If y'all have done what I'm trying to do chime in and tell me about. Will listen to all criticism, good or bad.
     
  10. flamedabone
    Joined: Aug 3, 2001
    Posts: 4,887

    flamedabone
    ALLIANCE MEMBER

    The half rack works perfectly fine, it is just not real cool to look at and will kill the vibe of a traditionally built car. Might be able to get away with it if you have fenders, but even then, I wouldn't tell anybody...

    -Abone.
     
    1927graham likes this.
  11. BC Texas
    Joined: Mar 14, 2011
    Posts: 32

    BC Texas
    Member
    from Arp. Texas

    This 29 coupe has 31 sunvisor, fenders and splash aprons. Only thing is, will have only hood top. Maybe I can cover it with a shield.
     
  12. BC Texas
    Joined: Mar 14, 2011
    Posts: 32

    BC Texas
    Member
    from Arp. Texas

    By the way. What do you consider proper? Just wondering.
     
  13. Non reversed corvair box, '37 and later ford box, 904 GM box?

    Nothing against your choice of steering gear, lots of fellas use R&P but they didn't really become popular for hot rods until the '90s.
     
  14. BC Texas
    Joined: Mar 14, 2011
    Posts: 32

    BC Texas
    Member
    from Arp. Texas

    True. I'm trying for the 60's look. More specifically like an older friend had in 66 & 67. Also, us elderly guys need all the comfort we can get. (Or pay for.)
     
  15. Was hoping to see a Model A fitted with one of these;

    [​IMG]
     
  16. 30 thousand miles with Mustang steering and a 4 bar. You don't need a panhard bar. !!!!!!!!!!!!!!!!!!!!!!!!
     
  17. BC Texas
    Joined: Mar 14, 2011
    Posts: 32

    BC Texas
    Member
    from Arp. Texas

    Bring it to me and I'll put it in one. (Kidding)
    Airplane?
     
  18. BC Texas
    Joined: Mar 14, 2011
    Posts: 32

    BC Texas
    Member
    from Arp. Texas

    Airplane? Or what
     
  19. badshifter
    Joined: Apr 28, 2006
    Posts: 3,300

    badshifter
    Member

    Full gendered? Like Bruce? or Caitlyn?
    Full gendered and "chopped" should never be used in the same sentence......
     
  20. that procedure is a deductadicktomie.
     
  21. I found that my front end walked a bit. After really watching the front end I noticed the axle was moving side to side a little at the shackles. I added a front pan hard bar from welderseries.com and it made all the difference in the world. Early on I had a lot of squat in the back right and added a rear panhard bar from the same guys. They made all the difference in the world on mine. Don't do a dead perch...
     
  22. BC Texas
    Joined: Mar 14, 2011
    Posts: 32

    BC Texas
    Member
    from Arp. Texas

    Explain "dead perch" for me. Probably seen but don't remember.
    I built a 31 roadster. Beefed up B flathead 4, 4 speed & 47 pu (411) with steering from same truck. Split 36 bones and had to install panhard bar. Rear moved on hard acceleration. Wanted a ways link, but someone wanted it worse than me. Been kicking my but ever sense. Wish I had it back. This one I hope will be a good cruiser. Promised my other half she would enjoy going in it. Used orig wishbone, but picked up another 36 last weekend. Will split and go out to frame. Thanks for your input.
     
  23. basically a dead perch replaces one shackle with a fixed front spring perch eliminating movement you get from a shackle. But it was intended for use with race cars. It throws off the geometry of the front end flex. Your leaf is bolted in the middle, so equal up and down flex on either side is the result. When you use a dead perch it locks one side keeping it from flexing normally. This is fact... people use them and like them and will tell you what I am saying is BS but, its physics. does it work? can you feel the difference? I don't know, some say yes, some say no...

    http://www.est1946.com/adjustabledeadperchset.aspx
     
  24. The Panhard engine is from one of these;

    [​IMG]
     
    winduptoy likes this.
  25. BC Texas
    Joined: Mar 14, 2011
    Posts: 32

    BC Texas
    Member
    from Arp. Texas

    OK. Thanks for the info. Have to think on that a bit.
     
  26. 27troadster
    Joined: Mar 14, 2013
    Posts: 105

    27troadster
    Member

    With cross steering, including rack and pinion only using one side of the rack, you should use a panhard rod for the reasons given by flamedABone and olskoolrodder above, ie: 1) the axle will move side to side from the pressure of turning the wheels and 2) the axle will move side to side going around corners, hitting bumps, etc.

    NOTE: The following is a discussion on how to properly set up a front end. It is not a discussion on what you can get away with.
    Additionally, to get rid of bump steer, the axle needs to move in the same arc as the drag link. See the attached drawings, one is for a conventional steering box, the other would be with a 1/2 rack, the only difference would be the length and mounting points of the drag link and therefore, the length and mounting points of the panhard rod. The blue arc is the arc that the end of the drag link will follow and the red arc is the arc that the axle will follow. If they are not similar, then when the axle moves up and down the axle will move differently than the end of the drag link which will cause relative side motion between the pivot point where draglink is attached to the steering arm and the kingpin which will result in the wheel turning left or right even though the driver is holding the wheel straight. This unwanted motion is called bump steer because the car will “steer” left or right when you hit a bump. To make the arcs similar, the panhard rod and drag link need to act like parallel bars, so the builder needs to make the panhard rod as close to the same length and mounted in as close to the same position on the frame and axle as practical (but don’t take my word for it, take a look at a stock ’46 or so Ford). The more the two deviate the greater the chance for bump steer.


    Now, there’s a lot of shit you can “get away” with, but:
    1) You won’t know how much until you build and drive it
    2) A little deviation from ideal here and a little there, sometimes they miraculously cancel, but more often than not they multiply their effects in a not so good way
    3) Why? A properly set up front end will drive and handle beautifully the first time
    4) People figured out how to make cars go straight 130 years ago, no sense reinventing the wheel in this department
    5) I recommend Tex Smiths’ book on hot rod chassis, and reading some old Motors books from the ‘30s and ‘40s they will explain the “whys” behind what the factory did to get cars to go straight without fighting the steering wheel.

    My $.02 – build it right the first time and you will have a hot rod that is fun to drive, else, standby for a car that you hate to drive or will have to do rework on.

    Some options on what you are attempting:
    It’s not traditional at all, but: they have those electric power steering boxes that go on the steering column under the dash where it would be hidden from view. They are stock on some new cars (I’ve no idea which ones) or there are aftermarket street rod companies that sell them. If you want the ‘60s look, with power steering, I assume due to father time, then I would use one of these along with a conventional (not rack and pinion) manual steering box. Given the option between a cast aluminum R&P that looks out of place and one of these under the dash units, I’d use one of these …no brainer there.
    For really traditional, find a box, column and steering wheel out of a fat-fendered ford. The box can be rebuilt from Mac’s for ~$300, kind of expensive, but period correct for cross steer.
    I’ve also heard really good things about the needle bearing kingpins from Speedway, I’ve been told it’s like driving with power steering, don’t know personally, but its worth a try I suppose.
     

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    Last edited: Nov 12, 2015

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