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Hot Rods Cowl Steering and Suspension setup

Discussion in 'The Hokey Ass Message Board' started by green73, Oct 1, 2017.

  1. Did a bit of searching on Cowl steering referencing a dead perch and or panhard bar. Maybe it was how I searched, but I found no info related. I'll be running a f1 box and the hairpin style steering arm at the spindle. Should I just plan on a panhard bar with no question, or do I need at all one with cowl steering? if I am missing a thread somewhere can someone send me a link. Again I found tons on just the steering just nothing mentioning the panhard or dead perch.
     
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  2. krylon32
    Joined: Jan 29, 2006
    Posts: 6,529

    krylon32
    Alliance Vendor
    from Nebraska

    Several years ago I built a deuce roadster with conventional spring over axle/ hairpin wishbones and hairpin steering arm on 37 spindles with Schroeder cowl steer and no panard. It drove fine with no bump steer or side sway. I'm currently driving a deuce pu with conventional front with deuce spindles and bones plus 37 Hudson side steer and it also drives fine with no panard. Both vehicles have steering dampers.
     
    Last edited: Oct 1, 2017
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  3. Hackerbilt
    Joined: Aug 13, 2001
    Posts: 6,243

    Hackerbilt
    Member

    NEEDING a panhard or dead perch depends on a lot of factors.
    How well a dead perch will work is dependant on a few factors as well.

    Can't really go wrong with a panhard bar if set up correctly, but then again if the suspension itself is set up correctly on the early Fords, and you use side steer, you can get away fine without that too.

    Any rocking side to side of the axle with cross steer will give you unwanted steering input. With cross steer I think I would just go with a panhard anyway, just for the safety.

    Knowing nothing about your car, there isn't much anyone can 100% recommend either way.
     
  4. Forgot to add that I have 1940 split bones. My chassis is a pinched 32 aftermarket piece. So, I am thinking about going without either option for a while and just see if I am comfortable with the handling for a while. I am just trying to keep the suspension as simple and bare bones as possible. Please anyone else running cowl steering please pipe in with input. I'm taking it all in.
     

  5. Pete Eastwood
    Joined: Jul 27, 2011
    Posts: 944

    Pete Eastwood
    Member
    from california

    If you are going with split wishbones & cowl steering, like you see on a lot of popular cars, just be aware that it is going to have a lot of bump steer . . . .
     
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  6. acme30
    Joined: Jun 13, 2011
    Posts: 164

    acme30
    Member
    from Australia

    As I understand it a panhard bar and dead perch are designed to limit side to side movement and thus are useful additions to cross steering set ups (because cross steering can tend can "rock" the axel from side to side).

    But cowl steering uses push pull method of steering so it will not rock the car side to side.

    Note panhard bar might still be useful but push pull negates some of the reason for installing panhard
     
  7. Pete Eastwood
    Joined: Jul 27, 2011
    Posts: 944

    Pete Eastwood
    Member
    from california

    Since this thread is titled "Cowl Steering and suspension setup", I'm going to add something I've wanted to address for some time.
    If you are thinking of using split wishbones / hairpins, with cowl steering, like the current, popular trend, I would encourage you to rethink that choice.
    The most common way of utilizing cowl steering, like as seen on many popular cars today, results in bump steer. Usually massive bump steer.
    If you ever have the chance, and can get the owner of a cowl steer car to agree, with the car parked, have the owner move the front suspension up & down & watch what the steering wheel is doing.
    It will saw back & forth.
    Do the same to a correctly executed side steer or cross steer car & there will be no ( or very little )steering wheel movement.
    What this means, when you drive a cowl steer car, & you grip the wheel tightly, the car will change lanes when you hit a dip or bump.
    To avoid this, requires holding the steering wheel loosely so when a dip or bump is encountered, the wheel can rotate back & forth in your hands, so the car can continue on a straight path.
    If that sounds like a fun way to go, well then have at it.
    There is a way to have cowl steering that works correctly ! It requires using a 4 link,
    The drag link & the 4 link bars should be parallel with each other & fairly close to the same length.
    I've driven a couple hundred thousand miles in '32 Fords, a good handling car is a joy to drive, a poor handling car is work to drive & soon becomes no fun . . . .
     
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  8. Thanks Mr. Eastwood for the experience based input. This is the type of info I an looking for to help guide how my car goes together. So, as I am understanding it now, the "push/pull" steering design minimizes the side to side motion that a cross steer layout does. However the suspension motion being up/down transfers potentially unwanted/unpredictable action to the pitman arm via the hairpin/drag link... Guess it's tough to have your cake and eat it too with my planned layout.
     
  9. rooman
    Joined: Sep 20, 2006
    Posts: 4,052

    rooman
    Member

    When engineered correctly cowl steer can work great. I have ridden in Jo Kerr's "A" for several thousand miles (1150 of them in 19 hours straight) and it has no discernible bump steer. The pivot for the split wishbone is almost directly below the steering arm pivot axis and the drag link runs parallel to the wishbone axis due to the fact that the steering arm is raised well above the king pin boss. The radius rod and the drag link are also very close to parallel in the vertical plane. When the suspension articulates the effect is very much like that of a four bar in that the axle and the steering arm move in the same arc. In contrast I have seen lots of cars with "conventional" frame mounted steering boxes where the drag link runs up hill to the steering arm and is way shorter than either the wishbone/hairpin/parallel four bar thus introducing conflicting arcs and a lot of bump steer.

    IMG_2615.JPG
    IMG_2612.JPG

    Roo
     
  10. krylon32
    Joined: Jan 29, 2006
    Posts: 6,529

    krylon32
    Alliance Vendor
    from Nebraska

    I think my roadster with Schroeder steering and my current deuce pu with Hudson steering do not exhibit bump steer because the front end moves so little vertically?
     
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  11. denis4x4
    Joined: Apr 23, 2005
    Posts: 3,530

    denis4x4
    ALLIANCE MEMBER
    from Colorado

    I'm using a Schroeder sprint car box on a car with hairpins and quarter elliptic suspension and I've never experienced bump steer. MVC-016S (2).JPG
     

    Attached Files:

  12. Pete Eastwood
    Joined: Jul 27, 2011
    Posts: 944

    Pete Eastwood
    Member
    from california

    Hey Keith "Rooman"

    You & I are long time friends, but I'm going to have to challenge you on this.
    The photo's you provided show exactly what I'm talking about.
    That is the perfect case for extreme bump steer.
    Next time you are around Jo Kerr's car, push down on the front suspension & watch the steering wheel, you'll be surprised.
    Here's what's happening in this set up.
    The entire front suspension is pivoting from the point where the wishbone attaches to the frame.
    That includes the point where the forward end of the drag link attaches to the arm at the spindle.
    So the forward end of the drag link is moving in an arc controlled by the wishbone mounting point, during suspension travel, not the arc created from it's attachment point at the pitman arm. The arc created by the forward end of the draglink pivoting from the pitman arm during suspension travel is fighting the arc it is actually traveling in dictated by the wishbone mount.
    this is the cause of the "bump steer"
    The split wishbone being "Parallel" with the drag link makes no difference. It's all about the pivot points, the wishbone could be a pretzel instead of a straight line, it would make no difference.
    Roo, go to page 4 of the "Pete & Jake's" catalog, 3rd picture down, there it is fully illustrated.
    There it is shown with Mustang steering for the example, but the attachment points are the same, creating the same scenario as you've shown with cowl steering.
    I wish everyone would take the time to read the first 4 pages of the "Pete & Jake's " catalog.
    Jake wrote & illustrated that 40 years sago & it's still the best information you'll get!
    The driver of a car with bump steer will learn to adjust & compensate for the bump steer, but that doesn't make it correct.
     
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  13. krylon32
    Joined: Jan 29, 2006
    Posts: 6,529

    krylon32
    Alliance Vendor
    from Nebraska

    Pete: You've forgot more about chassis building than I will ever know and your theory of bump steer is correct. But look closely at the picture rooman posted and notice that there is probably less than 1 inch of front travel by looking at the shock. That may be why he is not experiencing noticeable bump steer? My deuce pu is set up much like the hot-rods of the 40/50's and I can't explain why my truck drives so dam good with long 32 split bones mounted at the edge of the frame with 32 tie rod ends, 37 Hudson steering in the stock 32 location with a 34 pittman, 32 ends on the drag link running up hill to a dropped 32 axle with 32 spindles with steering arm contoured to the axle. Stock style 32 tie rod and a P&J steering damper. I just did short ride over some rough roads at 70 mph and do not experience bump steer. Maybe I just got lucky?
     
    Last edited: Oct 3, 2017
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  14. JOECOOL
    Joined: Jan 13, 2004
    Posts: 2,757

    JOECOOL
    Member

    I am about halfway knowing nothing about what you guys are talking about . Are you talking about the normal frame mounted ,mustang or corvair box or are you talking only the boxes mounted up higher on the cowl? sorry trying to keep up with you all .
     
  15. alchemy
    Joined: Sep 27, 2002
    Posts: 15,785

    alchemy
    ALLIANCE MEMBER

    Mr. Easwood,
    So to eliminate the bump steer from a cowl mounted setup, you would need the bottom joint on the pitman arm to be in the same place as the rear joint of the wishbone (up, down, back, and forth)? Then it would be perfect arcs that match?

    Do you find that the very short travel a typical hot rod front suspension has makes the small amount of bump steer unnoticeable? Or at least not a big enough problem to make a guy give up the "look" he is after?

    What about the cowl steer setup on the vintage sprinter you are building? Do the parallel springs on the front make much difference in the bump steer?
     
  16. Pete Eastwood
    Joined: Jul 27, 2011
    Posts: 944

    Pete Eastwood
    Member
    from california

    Krylon32,
    You're right about the limited suspension travel, limiting the bump steer.
    The set up on your car sounds something like the first & second image's on page 4 of the "Pete & Jake's" catalog, take a look. I bet your car drives just fine !
    Take a look, that is a good functioning set up.
     
    Last edited: Oct 3, 2017
  17. Pete Eastwood
    Joined: Jul 27, 2011
    Posts: 944

    Pete Eastwood
    Member
    from california

    Alchemy,
    Your correct, that is ideal, but some small compromise can work
    The first & second image on page 4 Of "Pete & Jake's " catalog show this.
    Yes the small amount of travel mask's the bump steer problem.
    On the sprint car, with the parallel springs, the axle is not moving in an arc, and the extremely long drag link creates very little arc in the draglink movement. The result is no (or little ) bump steer.
     
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  18. krylon32
    Joined: Jan 29, 2006
    Posts: 6,529

    krylon32
    Alliance Vendor
    from Nebraska

    Those drawings are very accurate if the front was moving in the full arc shown in the drawings. In reality most of the front end setups built today, the end of the axle on most roads doesn't move vertically much more than an inch which would limit bump steer. In theory the front should move that much but with today's low front end setups vertical travel is not 4 inches. My deuce pu front is basically like drawing # 2 on pg 4 but with the bones up close to the bottom of the frame and the axle closer to the bottom of the frame and a little more upward drag link angle. Jake states at the end of the paragraph (Fortunately the difference in the arcs is still very slight within the limited amount of vertical suspension movement and bumpsteer, if any would be insignificant) Sometime when your in the neighborhood stop by and drive my truck, how good it drives even surprises me.
     
    Last edited: Oct 3, 2017
  19. rooman
    Joined: Sep 20, 2006
    Posts: 4,052

    rooman
    Member

    Pete,
    I see your point and krylon32 may be correct in that Jokerr's car maybe does not use a lot of suspension travel going down the road. All that I really know is that I have never seen Jokerr fighting to keep the car in a straight line while riding with him over any sort of road surface. Maybe the length of the wishbone and the fact that it is (at worst) parallel to the ground plane at ride height combined with little suspension travel make the car steer so well. I just plotted it out roughly using a 35" wishbone/radius rod and the steering arm 12" above the axle and the displacement is around 1/2" with 4" of vertical travel. Maybe I should stick to dragsters. :confused:

    Roo
     
  20. Pete Eastwood
    Joined: Jul 27, 2011
    Posts: 944

    Pete Eastwood
    Member
    from california

    Roo
    Nobody is saying the driver has to "fight" the bump steer. The driver will compensate for the bump steer. Again, the limited travel helps mask the condition.
    Hot rods can be built without bump steer, so why build one with ?
    Shouldn't we build the best driving cars we can ?
     
    Last edited: Oct 3, 2017
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  21. silent rick
    Joined: Nov 7, 2002
    Posts: 4,018

    silent rick
    Member

    in a perfect world, yes. but the reason we come to the hamb is because we're drawn to a certain era. we try to emulate what was done back then so we tend to build our cars the way they were 60-70 years ago. we are aware of bump steer and try to modify our steering and suspension so as to limit it without giving up the look we are after.

    don't get me wrong, i'm sure everyone on the hamb appreciates your expertise and welcomes everything you have to say. i'm just trying to explain our motives for the way we do things. we are not rat rodders. we don't want to put a dangerous vehicle on the road and give the hobby a bad name.
     
    Last edited: Oct 3, 2017
  22. alfin32
    Joined: Jun 20, 2006
    Posts: 1,396

    alfin32
    Member
    from Essex, Ma.

    WOW, what an education I'm getting, thanks guys.
     
  23. Pete Eastwood
    Joined: Jul 27, 2011
    Posts: 944

    Pete Eastwood
    Member
    from california

    You can emulate what was done back then & still build a good driving car.
    If guys aware of bump steer, why are the same mistakes being repeated?
    Oh by the way, I don't remember seeing a lot of hot rods with cowl steering being built 60-70 years ago.
     
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  24. silent rick
    Joined: Nov 7, 2002
    Posts: 4,018

    silent rick
    Member

    i guess we were all emulating race cars built in the 30's

    [​IMG]

    [​IMG]

    [​IMG]
     
    Last edited: Oct 3, 2017
  25. Thanks so much everyone for providing experience and knowledge on this subject. Tons of information to take in and process before I start making things too difficult to undo. Just for clarification for a previous question posted above. This is about the box being mounted up high in the cab side of the firewall. For my clarification, I am now of the mindset that a car set up like this does NOT require/need a panhard bar or dead perch, correct? It is more about getting the geometry of the pivot points in an acceptable orientation? Please keep the debate/conversation going.
     
  26. alchemy
    Joined: Sep 27, 2002
    Posts: 15,785

    alchemy
    ALLIANCE MEMBER

    I also don't remember a single hot rod in the old magazines with cowl steering. But not very many had quickchanges or Halibrand wheels either. So we steal style from the race cars, and apply it to our "traditional" hot rods. Sure looks cool though, don't it?
     
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  27. Pete Eastwood
    Joined: Jul 27, 2011
    Posts: 944

    Pete Eastwood
    Member
    from california

    This "Boyle" car shows a perfect cowl steer / split wish bone configuration !
    This car will have no bump steer . . .
    the higher the drag link / pitman arm pivot is raised above the wish bone mount, the more extreme the bump steer

    Boyle products Indy car.jpg
     

    Attached Files:

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  28. swanwaco32
    Joined: Feb 7, 2005
    Posts: 144

    swanwaco32
    ALLIANCE MEMBER

    Pete is correct...!!!
     
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  29. alfin32
    Joined: Jun 20, 2006
    Posts: 1,396

    alfin32
    Member
    from Essex, Ma.

    It would be great to get feedback from Ken, Keith, Dave, Jo-Kerr, and anyone else who has actual seat time, and thousands of miles under their belts. I LOVE the look, but hear mixed reviews of what they're actually like to drive.
     
  30. Pete Eastwood
    Joined: Jul 27, 2011
    Posts: 944

    Pete Eastwood
    Member
    from california

    I did alot of the restoration work on the Doan Spencer car when I worked at "So Cal"
    I was the first to drive it after the restoration & have driven it several times since.
    It suffers from bump steer.
     
    Last edited: Oct 5, 2017

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