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Technical Alignment information.

Discussion in 'Traditional Hot Rods' started by hardtimesainit, Nov 30, 2017.

  1. dirty old man
    Joined: Feb 2, 2008
    Posts: 8,754

    dirty old man
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  2. Mr48chev
    Joined: Dec 28, 2007
    Posts: 27,900

    Mr48chev
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    I'd have to go out back and look at my Model A axle and wishbone but I am sure that on it the tie rod runs under the wishbone. At any rate that whole setup looks a bit wonky. Ah hell I'll just go look at my stock setup and figure it out.
    Update:
    Looked at my stock axle and wishbones and sure enough your are correct, the stock A tie rod does run above the wishbones. As many times as I have moved that thing around over the past 35 years I never paid a lot of attention to it. I didn't realize that he had used all the stock pieces.
     
    Last edited: Dec 2, 2017
  3. DeucemanLt1
    Joined: Aug 15, 2014
    Posts: 145

    DeucemanLt1

    Looks like spindles are on wrong sides, putting steering arms on top of axle. This messes everything up. Dropped axle also adds to decreasing caster when stock wishbone is used. Split bones or hairpins could correct this but a bigger problem is spring twist in the cross member.


    Sent from my iPhone using H.A.M.B.
     
  4. hardtimesainit
    Joined: Jan 24, 2009
    Posts: 401

    hardtimesainit
    Member

    Well, I ask about front end geometry , because there are different ways of doing things...in hotroding/mods. I'm not one to say what is right or wrong...simply because I don't know ! I do know when a car is not driving/handlng correctly, and mine is not.
    To directly answer your questions, the front axle was installed with some old timey heating/bending methods. And, all parts were set to clear other parts. Otherwise....everything that you are looking at on front end is stock '30 A roadster all rebuilt (new ball ends, etc) . Now what isn't stock is that I put a left and right hand threads on the ends of both rods(drag link and tie rod) , to make adjusting toe and slop out of system...easier.
    F100 steering box rebuilt. Oh, and Lincoln brakes all around from mechanical stock system.
    Yes, when I put the new axle in, I put steel belt 600x16 Coker tires on all four wheels. Put (I think) 1/6" toe in adjustment. All of this was done in driveway with torch/hand tools. Seemed to drive well, but NOT as I expected. Then I put the B&Ls on and things went south when I'd hit ANY irregularities on road.

    This next week, I'm putting the 600x16s back on and am going to locate a front end shop...(hopefully)familiar with old cars. I think that I created my problems two ways. First , by not having a shop check and determining status of geometry; second, by putting on B&Ls when front end was not even verified yet as having proper caster/toe.
    I've come to this conclusion from reading ALL of the input from you guys. Not rocket science, but important for health/safety of car and me ! Yeah, maybe B&Ls look good and the Firestone deluxe champion tires are good tires, but I'm more of a driver and not into looks so much...so they are out of here, if I can't get stable front end with them..
    How to select a shop that can do work honestly. I already called one 'reputable' shop and he says....we will 'heat/bend' front axle to align. Whooah, not mine you won't !!
     
  5. DeucemanLt1
    Joined: Aug 15, 2014
    Posts: 145

    DeucemanLt1

    I stand corrected on the tie rod position. Further looking online shows factory A’s were tierod above wishbone as were the steering arms.


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    DLRIDES likes this.
  6. SquintBoy
    Joined: Mar 19, 2011
    Posts: 97

    SquintBoy
    Member

    All these guys bring up really good points. If you want a few more no cost checks to try to get a little closer to your biggest problem, here goes:
    1. Swap your big n littles front to rear.
    2. Swap in a known good set of mounted radials from one of your buddies.
    If one of those doesn't make a major difference, then go after the other suggestions.
    Another freebie (but it's probably not your problem) is checking toe. Stand 4 oil quarts on edge, 1 in front and 1 in back of each front tyre. Lay a straight edge (like a yardstick) on top of the qts pushed against the outsides of the tyres. Then take a front & rear measurement across the car. Takes a helper to push the other straight edge against the other tyre. With cross (bias) ply tyres you should be looking for a good 3/16" bigger behind the tyre dimension. That's toe in.

    Good luck.

    sent from the red phone
     
  7. metlmunchr
    Joined: Jan 16, 2010
    Posts: 752

    metlmunchr
    Member

    Couple things..... OP says at one point that the 6.00's were steel belted, so I assume radials. No mention of whether the replacements were radial or bias. If bias, they will have a greater tendency to wander as compared to the radials.

    Zero scrub radius isn't a desirable thing as it makes for an unstable situation. The purpose of toe in is to compensate for all the various points of slack in the steering system. In the case of a beam axle, it compensates for the slack in the tie rod ends such that there's actually no toe in or out as the car rolls down the road. To accomplish this, it's necessary to have something to create a force that puts the tie rod in either tension or compression, depending on whether the tie rod is in front of or behind the axle.

    A torque is created by the rolling resistance of the tires multiplied by the scrub radius. Rolling resistance is the force and scrub radius is the lever arm. Assuming a positive scrub radius, this torque makes the wheels want to turn outward as the car moves, and, in the case of the tie rod behind the axle, the tie rod is kept in compression as it resists this torque. Zero scrub give zero lever arm and no torque, so the tie rod can cycle between tension and compression as the car rolls down the road. The tie rod never assumes a stable length, and this allows the wheels to wander back and forth within the limits of the length change of the tie rod.

    Rockwell actually built a heavy truck steering axle with zero scrub, called the Center Point Steer axle. The purpose was to make trucks without power steering easier to steer at low speeds. They worked well for the intended purpose and a truck would steer at low speeds as if it had power steering. However, at highway speeds, the lack of stability due to a largely unloaded tie rod showed up, and to drive one of these critters down the road made you think you were steering with a pair of ropes tied to the steering arms.

    As mentioned previously, front wheels with a lot of offset that creates a large scrub radius makes for an ill driving beast, but some scrub distance is necessary for stability. Unlikely that this would be the problem on the OP's car, but worth mentioning for general knowledge of the purpose of a couple pieces of front end geometry.

    As for the OP's problem, going to a 4" dropped axle without a corresponding adjustment of caster would put the caster at the lower limit of acceptability at best. Adding a couple more inches of rake via tire sizes would have to leave the car way short of caster. The extreme lack of parallelism between the drag link and the wishbones doesn't help either.
     
  8. hardtimesainit
    Joined: Jan 24, 2009
    Posts: 401

    hardtimesainit
    Member

    "extreme lack of parallelism between drag link and wishbones" ...So how is that parallelism gained ? Maybe via shorter pitman arm ?? What negative effect on steering does that cause ???
     
  9. hardtimesainit
    Joined: Jan 24, 2009
    Posts: 401

    hardtimesainit
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    Well, today I did the change that you suggested, i.e.- switch B&Ls, back to front. Took roadster for a ride and it did GOOD ! So, this indicates that you guys suggestions for more caster is right on...correct ? 001.JPG
     
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  10. SquintBoy
    Joined: Mar 19, 2011
    Posts: 97

    SquintBoy
    Member

    Yes....but, don't rule out (on your littles) out of round tyres or wheels, poor construction or ply separations. Looks like time to measure and then go for more caster! Yeah!

    sent from the red phone
     
  11. SquintBoy
    Joined: Mar 19, 2011
    Posts: 97

    SquintBoy
    Member

    Just reread your post #38. To get the drag link more parallel to the ground or wishbone, you can't just shorten the pitman arm. There is a nice explanation in the Tardel book about the length ratio of the Putnam arm to the thingy it connects to on the LF backing plate. That ratio can't be changed much without adversely affecting steering.

    sent from the red phone
     
  12. Toe does other funny things, like grabbing the lines on the pavement. I've had cases where I swear the painted lines on the road made it wander.
     
  13. DeucemanLt1
    Joined: Aug 15, 2014
    Posts: 145

    DeucemanLt1

    Take it to a front end shop and find out what your caster is with both sets of tires (the B/Ls and your other set). Others have posted good info on what it should be but without knowing your baseline it will be hard to correct.


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  14. hardtimesainit
    Joined: Jan 24, 2009
    Posts: 401

    hardtimesainit
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    Thanks, I have a Tardel book. Just have to dig it out and re-read it now !
     
  15. hardtimesainit
    Joined: Jan 24, 2009
    Posts: 401

    hardtimesainit
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    Funny (odd) for sure as that's my experience with B&Ls on. Lots of our roads are let go to hell here. Some areas you learn to avoid altogether(Sun Valley). Front end shops are kept busy with NEW cars getting knocked out, so you can just imagine what such conditions do to a jewel like mine..ha !
     
  16. hardtimesainit
    Joined: Jan 24, 2009
    Posts: 401

    hardtimesainit
    Member

    You're right, it is time !
    Also correct in that there has been a wealth of good/helpful info given. Hoping that it will also help others here.
     
  17. More than likely the caster is the reason.
    But it could be the tires still.
    Caster is very easy to measure yourself and you can measure it with the B&L reversed and then installed as intended.

    Changing the caster is not so easy, it's usually done by cutting the wishbones at the big end and re welding them to correct the caster.
     
  18. Happydaze
    Joined: Aug 21, 2009
    Posts: 1,035

    Happydaze
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    And getting 'toe' checked by a 'technician' can be problematical when the spotty yoof hasn't ever seen, never mind understood, that rwd stuff toes in, because all he's ever seen / experienced is modern fwd crap, that toes out, irrespective of what the 'puter says (or doesn't). Getting old is getting old!

    Chris
     
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  19. hardtimesainit
    Joined: Jan 24, 2009
    Posts: 401

    hardtimesainit
    Member

    That 'modern man' is a concern of mine also. First question I asked a couple front end 'techs'...do you ever do front end work on old cars, like a '30 Ford ?
    Well, I'll let you all know what I find eventually, as something must be done to improve driving experience.
     
  20. doyoulikesleds
    Joined: Jul 12, 2014
    Posts: 277

    doyoulikesleds

    my bet would be your biggest problem is the caster since the wishbone mount looks hand made. I think I would remake the mount for proper caster with the tires size you are going to run and fix your drag ling angles
     
  21. I help a friend out now and then that gets an old car in for an alignment. He has a shop and the favor gets me lift priviledges when I need them.
     
  22. All you have is caster, camber, toe, steering wheel center.
    On the straight axle :
    camber is in the bend (drop) of the axle.
    It can not be "adjusted" it needs to be bent with heat.
    Caster is all within in the axle mounts ,
    If stock Wishbones are present there is no adjustment they need cut and welded. If split bones the frame mount can be manipulated but not much and the bone ends need to be cut and welded. If you have radius rods there's some adjustments in the rod ends. Radius rods as well as split bones can also adjust axle squareness to the chassis.
    Toe is adjustable within the tie rod.
    Steering wheel center is adjustable in the drag link.

    Caster is easy to check in the garage. Park the at level at ride height and drop a gravity operated angle finder on the king pin.
    Toe is a bit more involved, a jig or two people who understand what they are trying to measure and done in the garage.
    Easy to chech camber as well, but but but the spindle need to exactly centered straight ahead at the correct toe. Camber and caster are measured as the tires relate to the road(ground). Toe is measured as the tires relate to each other off the center line of the chassis.
     
    Last edited: Dec 5, 2017
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  23. 31 Vicky
    Do you have general spec's that you like?

    Phil
     
  24. Every car is going to want something different to drive it's best.
    Tire size, type, pressure, wheel offset, scrub, weight, wheel base, return to center, steering effort ect blah blah all make a difference.
    But , Generally toe in rarely more than 1/8" and someplace around 5* caster to start from.
    I drive them and take notes. Make adjustments & take notes until improvements reverse and then back track to last improvement. It's not a quick 45 min red/green "computer says so" process. Not that they are ever perfect, but they are the best they can be with the present components and parts at that current amount of wear.

    A guy brought me his 34 roadster that was flat out scary to drive. He had it to a few shops, and a bunch of new parts thrown at it. Rod ends, steering box, steering u joints, even sold him a new column a couple red/green printouts too. None of these guys were very familiar with old ford style suspension but good shops. His king pins were super sloppy. My little sister could have found it if I showed her how to check it. I have no idea if he really needed all those other parts or not, but if they were throwing parts at it why not change the king pins that were noticeably sloppy instead of throwing in the towel?
     
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  25. hardtimesainit
    Joined: Jan 24, 2009
    Posts: 401

    hardtimesainit
    Member

    Thanks ! Good eye regarding the wishbone mount.
    Actually, you see an aluminum adapter to mate the '39 trans to the '32 B engine. This adapter is/was made by a guy who supplied the wishbone ball mount. It is 'bolted' to the bottom of the trans bell...quick/easy install. But, I can see what you are saying. However, I take it that remaking this 'mount' would have to hold the ball in a LOWER position to increase caster..no ?
    If so, I might have situation of longer mount running into ground obstructions ?
     
  26. hardtimesainit
    Joined: Jan 24, 2009
    Posts: 401

    hardtimesainit
    Member

    Lucky guy !
    I'm looking for property near 31 Vicky's area for same privileges...lol
     
  27. hardtimesainit
    Joined: Jan 24, 2009
    Posts: 401

    hardtimesainit
    Member

    Thanks much for your valuable input/help !
    Yeah, I don't think that any of us appreciate....a parts replacer...to solve our car problems. Diagnosis , done correctly takes a certain amount of experience/knowledge and is an art, IMO. This is why most of us without, ask you guys with !
     
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  28. DeucemanLt1
    Joined: Aug 15, 2014
    Posts: 145

    DeucemanLt1

    You cannot change caster by moving the wishbone or bones up or down. That will only twist and bind the spring eyes and perch. You may raise or lower the attachment point if necessary but the caster can only be changed by rotating the spring cavity in the crossmember. This of course includes repositioning the ubolts and bottom spring holder. Essentially, the caster is 90* to the relative angle of the crossmember spring cavity at ride height.


    Sent from my iPhone using H.A.M.B.
     
  29. alchemy
    Joined: Sep 27, 2002
    Posts: 16,077

    alchemy
    Member

    Deuceman, you are kinda wrong. You CAN change the caster by moving the back end of the wishbones up or down. It will twist the spring, but it will work. I mean it really shouldn't matter too much, because springs were made to bend anyways, right? You're only twisting the spring a degree or so.
     
  30. When does twisting the spring become a bind?

    Phil
     

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