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Technical Cowl Steering, first time

Discussion in 'The Hokey Ass Message Board' started by wstory, Oct 27, 2015.

  1. wstory
    Joined: Jul 4, 2008
    Posts: 1,288

    wstory
    Member
    from So Calif

    So to the outside of the cowl,....I liked the shape of the VW tail-light housing but modifying to fit was more work than beginning from scratch. It was pretty simple to establish the surface perpendicular to the pitman center line which is also parallel to the center line of the car. Next was to establish the plain of the cowl, which is angled toward the car's center line looking from above. Drew a circle for the outboard surface and an ellipse where it met the cowl and then "connected the dots" with cardboard for a pattern and then transferred the shape to 18ga,
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    dwollam and 117harv like this.
  2. 50Fraud
    Joined: May 6, 2001
    Posts: 9,735

    50Fraud
    Member

    Elegant, Bill. Looks like you know what you're doing.
     
  3. wstory
    Joined: Jul 4, 2008
    Posts: 1,288

    wstory
    Member
    from So Calif

    [​IMG]
    I'd seen these wrenches from time to time at the swap meet and always thought they'd make a cool pitman arm. They're called "slug" or "striking" wrenches. They're used on those big bolts and nuts you see on bridges and utility poles you always wondered about. Riggers beat on 'em with sledge hammers. They're made in the USA, are forged and you can still buy them new in sizes so large it takes two hands to lift one.
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    I needed the spline so cut the end off the Ford pitman arm and shaped it to match the hex in the wrench, ultimately welding it to the wrench on the back side.
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    And then bending per standard bending practice for forged components.
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    The working length was already determined by earlier mock-ups. The drag link end was finished with a replacement ball for 32/Model AA tie rod.
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  4. wstory
    Joined: Jul 4, 2008
    Posts: 1,288

    wstory
    Member
    from So Calif

    Tx but it's more a matter of just goin for it. It's amazing what you can get away with :rolleyes:
     
  5. looking good so far! nice work
     
  6. wstory
    Joined: Jul 4, 2008
    Posts: 1,288

    wstory
    Member
    from So Calif

    A little "side-bar" is,.........I'm likin the coloring that comes with heat. That's become the theme for the mechanicals. It's a bit hard to control. Ya never know what you;re gonna get. To inhibit rusting, the pieces were coated in a High-Temp satin clear by VHT which require a heat (BBQ) cure. The clear and the baking reduces the color intensity. Worked on everything but the headers.
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  7. wstory
    Joined: Jul 4, 2008
    Posts: 1,288

    wstory
    Member
    from So Calif

    So,..one of the parameters was to get the steering arm long enough to clear the tire at full lock and thread the needle between the shock and headlight. That dimension approximated the length needed for a "friendly" steering ratio. It took a little fudgin.
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    And there you have it.
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    It all worked quite well. I intended to have the steering shaft rigid mounted to the input shaft but lost control of the angles and missed by about 2 degrees. After all the calculatin and mocking up and wasting steel, it was waaaay too much work for 2 degrees to redo,..... Therefore, the U-joint.
    What you see yields decent foot room and the wheel is where I like it.
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    Last edited: Oct 30, 2015
    dwollam and kidcampbell71 like this.
  8. tikiwagon13
    Joined: Feb 23, 2011
    Posts: 371

    tikiwagon13
    Member

    Nice, very nice.
     
  9. alchemy
    Joined: Sep 27, 2002
    Posts: 16,451

    alchemy
    ALLIANCE MEMBER

    Looks like you have a nice setup for low dollars compared to a Schroeder. I did a similar thing in my 26 T project, by using a reversed 70 Mustang box. I had to extend the sector shaft on mine to get the pitman outside the cowl tin. I wish I'd had known about the F150 box before I started because it may have been long enough for me.
     
  10. Hackerbilt
    Joined: Aug 13, 2001
    Posts: 6,247

    Hackerbilt
    Member

    Yes...it certainly makes a difference not to have to mess with an extended shaft.
    Great thread Mr Bill! :D
     
  11. rooman
    Joined: Sep 20, 2006
    Posts: 4,052

    rooman
    Member

    The added benefit of the mounting package is that it ties the whole cowl area together and I would assume that it has reduced cowl "shake" on rough surfaces and helped with door alignment.

    Roo
     
  12. Pretty damn slick - nice work!
     
  13. woodz
    Joined: Feb 23, 2010
    Posts: 517

    woodz
    Member

    Amazing job. Thanks for sharing.
     
  14. 340HilbornDuster
    Joined: Nov 14, 2011
    Posts: 1,916

    340HilbornDuster
    ALLIANCE MEMBER

    Awesome Work Man!!! Dig the Forged Wrench Idea!!
    Nice Ram horns...must be a Poly out there missing it's valve covers! Looks good!
     
  15. jamesd1502
    Joined: Jul 8, 2013
    Posts: 283

    jamesd1502
    Member
    from san diego

    Not as clean but similar with an F1 box ImageUploadedByH.A.M.B.1446338247.506311.jpg ImageUploadedByH.A.M.B.1446338286.739818.jpg ImageUploadedByH.A.M.B.1446338304.249124.jpg
     
    bct likes this.
  16. wstory
    Joined: Jul 4, 2008
    Posts: 1,288

    wstory
    Member
    from So Calif

    I like it.
    Your first? Is it on the road yet and are you satisfied with the drivability?
    After near 4K miles, I am pondering what I might do to "tighten" the steering response. I'm not ready to return to the Vega box but it was a bit more precise.
    What I see in your setup is, the steering arm is lower relative to the axle and you have split bones. Both of those items tend to stiffen the tendency of the axle to twist from the steering input. That's something I could do 'tho it means replacing the hairpins, figuring a diff. shock location and building a new steering and pitman arms.
    I'd appreciate any comment by you or others,......who have real experience!
    [​IMG]
     
  17. James Curl
    Joined: Mar 28, 2006
    Posts: 370

    James Curl
    Member

    I see your still fooling people with those valve covers. Have a friend who put 302 Ford valve covers on a Chevy in his 40 Ford coupe and got a big laugh when he heard people say its good to see a Ford in a Ford.

    Love your creativity on all of the projects you do, The Plymouth and the 32 have some very neat features. The front suspension set up on the 48 took a lot of thought and effort to make it seem so easy.
     
  18. rooman
    Joined: Sep 20, 2006
    Posts: 4,052

    rooman
    Member

    A long time ago I stopped in one morning to see my (late) friend Phil Hart at his shop. On the counter were a pair of small block valve covers with a Ford logo grafted into them. When I asked what idiot would do that his reply was, "This idiot who wants to take his duece coupe to the "All Ford Day this weekend"

    Roo
     
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  19. wstory
    Joined: Jul 4, 2008
    Posts: 1,288

    wstory
    Member
    from So Calif

    So here's a wrap-up.
    With about 5K miles on the new steering set-up I'm pretty pleased, However, it does have idiosyncrasies that give me pause. I've experienced a severe "Death Wobble" on several occasions,..... 3 times in 5-6 weeks. It only happens at very low speed, like 10 mph or less, and when the driver side wheel strikes a pot hole or speed bump. All the parts are new and tight. Angles are correct as I understand them. My take is,..... since the input from the drag link is high relative to the tie rod, and the steering load is transferred across to the passenger side wheel,.... there is opportunity for flexing of the axle and steering components and once started it's a harmonic thing whose only cure to stop. Ironically, the car and the steering are quite friendly at speed and it sure looks cool in my opinion.
    One BandAid that I will try (which bugs the shit outta me) is a steering dampener,...it's freakin a patch!!!! SoCal says they install one on every car that leaves their shop. I have one on the bench so my pride gets compromised and I will install it in the next few days.
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  20. 117harv
    Joined: Nov 12, 2009
    Posts: 6,590

    117harv
    Member

    Very nice, if you would could you post a nice driver side shot of the whole car with a nice back ground?
     
  21. Atwater Mike
    Joined: May 31, 2002
    Posts: 10,417

    Atwater Mike
    ALLIANCE MEMBER

    Mr. Bill: "OH, NOOO!" - regarding the steering dampener. (just a 'personal resentment' in aesthetics)
    But in this case, it seems to be the leverage your pitman arm has over the length of axle drop which sets off the 'shimmy'...the dampener is thusly 'called for' in your case. (downstream of a series of links, stemming from geometric leverage 'upstream'...)
    I'm confident you'll install it (temporarily) to confirm it, and if so, hide it as if it belongs there.
    Is that drag link knurled just forward of the pitman arm? Coooool....

    I set my '27 Highboy up with cowl steering in 1975. I was a BMW Master, and had access to a 1973 BMW Bavaria, with ZF MANUAL steering box! Car had been 'curbed', and various chassis parts condemned, I took the box home, and doctored the hub of the pitman arm, the secter shaft measured 13" from the center of the worm! ...and it turned in the correct direction, ratio was just right. (pitman arm ending up at 7.5", C/C.)
    My biggest concern was for engine clearance/steering box. I had engines from flatheads to Chrysler and Desoto Hemis, so wanted to avoid the worst possibilities, that was 'building headers for the remainder of my life'.
    I had a '38 Ford tube axle, so no trouble with drag link angle, or 'leverage twist'.

    Thank you for a most comprehensive thread...(Loved the VW bezel idea, but the Striking Wrench hit it out of the park! Best pitman arm ever.)
    Inspiring? IN SPADES.
     
    Last edited: Nov 15, 2015
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  22. wstory
    Joined: Jul 4, 2008
    Posts: 1,288

    wstory
    Member
    from So Calif

    I guess it could be good news if the dampener doesn't work! That way I wouldn't need to live with the appearance and I be forced to figure out something else :(
     
  23. bengeltiger
    Joined: Mar 3, 2012
    Posts: 469

    bengeltiger
    Member

    Great thread, I'll subscribe!
     
  24. rottenleonard
    Joined: Nov 7, 2008
    Posts: 1,973

    rottenleonard
    Member

    I believe a lot of the death wobble issues are do to tires that are completely outside of the scrub radius as the king pin is set at an angle for a much taller tire than what we typically use. Combine that with high caster angles (which helps almost everything but this issue) and you are introducing a bunch of camber roll as the tire turns starting this uncontrollable oscillation. So in some cases the dampener is really the most practical solution, otherwise you would have to bend the axle and build a custom spindle to fix the scrub radius.
     
    Last edited: Nov 16, 2015
  25. wstory
    Joined: Jul 4, 2008
    Posts: 1,288

    wstory
    Member
    from So Calif

    That's on my list of things to do.
     
  26. wstory
    Joined: Jul 4, 2008
    Posts: 1,288

    wstory
    Member
    from So Calif

    Hmmmm,.....hadn't thought of that. Yeah, may not be perfect scrub radius,...but close, I believe. Got 6.5 degrees of caster, and/but the shimmy never happened before with the Vega box.
    Other ideas/comments?....I'm open to any input.
     
  27. LODI3QTR
    Joined: Nov 27, 2006
    Posts: 37

    LODI3QTR
    Member

    Thanks for the link from......[​IMG]
     
  28. fstfish66
    Joined: May 28, 2005
    Posts: 376

    fstfish66
    Member
    from eastern pa

    subscribed, nice job
     
  29. 27troadster
    Joined: Mar 14, 2013
    Posts: 105

    27troadster
    Member

    First, absolutely beautiful work and craftsmanship! The T bearing cover, use of rebuildable drag link ends, etc, etc, just perfect.

    But.... I think you are experiencing bump steer, which I believe is starting your "death wobble" when the driver's side wheel hits a bump.
    drag link parallel bad way.png
    This diagram shows what happens when the end of the drag link follows a different arc than the axle, the drawing is for parallel bars, but the same basic idea can be applied to a radius rod / split 'bone set up. Lay out your suspension on cardboard, or scaled down on paper, then draw an arc through the knuckle on the steering arm. The center of the arc will be the pivot point where the radius rod meets the frame. This is how the axle will move. Draw another arc through the knuckle on the steering arm but this time with the center of the arc at the knuckle where the drag link fastens to the pitman arm. This is how the end of the drag link will move when the axle goes up and down. If these two arcs are not the same, then the end of the drag link will move fore and aft relative to the axle, even though your holding the steering wheel in one position, as the axle moves up and down, which causes bump steer. If you lay out your set up you will find that the two arcs do not coincide.
    The below was posted by "Ricks Garage" in the thread: http://www.jalopyjournal.com/forum/threads/hairpin-and-side-steer-box.997532/
    steering box-1.jpg
    It shows how to set up a drag link steering properly. If you draw out acrs with this layout, you'll quickly realise the only way to make the axle arc match the drag link arc is if the radius rod/split 'bone to frame pivot point coincides with the drag link to pitman arm pivot point. Since this is rarely achievable, the next best thing is to put the drag link - pitman arm pivot point on a line between the steering arm knuckle and radius rod pivot point, that way the two arcs will be similar through the normal range of axle motion.

    All of that said, putting the drag link where it should be:
    1. Looks kinda stupid because the drag link will be running up hill and it's not as pleasing to the eye as when the drag link is roughly parallel to the radius rods / split 'bones.
    2. Not possible with most cowl steering set ups, unless the pitman arm is made very long, which introduces other problems like steering ratio and flexing.

    Now everything I discussed is for bump steer, which I believe is driving your front end into a resonant death wobble. But the death wobble itself is due of parts flexing and acting like undampened springs. The use of the wrench for a pitman arm is super cool, however, it looks like it has a substantially thinner cross section than stock pitman arms, and therefore will twist much easier than a stock pitman arm. Because the drag link mounts about an 1" away from the center of the pitman arm, there will be a twisting moment as the drag link puts force on the ball of the pitman arm. I wonder if the "springyness" that is required for resonance to occur is mainly in your pitman arm. I would recommend trying a beefier pitman arm before going to a steering stablizer.


    Hope this helps.

    Kipp
     
    Last edited: Nov 25, 2015
  30. bct
    Joined: Apr 4, 2005
    Posts: 3,095

    bct
    Member

    Thanks for showing your cardboard mock up. I learned something there about X and Y
    and in between.
    Here is a similar box reversed and lengthened for my center steer go kart. Im still working on bracing. downloadfile-26.jpg
    downloadfile-17.jpg
     

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