Early Ford Steering Arm Angle - Set the record straight...

Early ford I-beam suspension with hair pin radius rods. Flaming River Vega cross steer. Trying to set up the front suspension in hopes of a maiden voyage to Fivewindow Johnnies' Gunnison Show next month. Question about the steering arms.

Most of this has been hashed ad nauseum here under the various Death Wobble threads (including the notorious Deth Wobbel one). That has resulted in some confusion due to conflicting opinions, so want to try this one more time to get a final consensus.

What is the CORRECT postion of the tie rod ends on the steering arms?

Some of the opinions suggest that the tie rod end should be parallel to the king pin axis. I believe that Pete and Jake's instructions state such. My steering arms as delivered provide that as demonstrated in this photo:



You can see that the square resting on the steering arms indicates a parallel condition relative to the king pin by looking at the bolts in the spindle.

However, **** Spadaro has stated, "The steering arms should have the tie rod bolt heads perpendicular to the ground not at an angle". I ***ume that the 7* angle indicated in the photo below would be incorrect in his opinion and the arms would have to be heated and bent upward.



The square is on the garage floor and the axle is within a half inch of riding height. The arm corresponds to the 7* of castor.

So which is it? Can't be both unless I set castor at 0*. Somebody out here has to have the final, definitive answer!

BTW - The heim end visible on the ground is the panhard bar. The tie rods will use normal rod ends.

Thanks for the help!

Tom

 

I can't think of any reason the rod end shouldn't follow the same axis as the kingpin. Leave them as-is. (Sorry ****, I have to disagree)

 

Your suspension is unwieghted and not at ride height at the moment. Best to check everything at ride height.

 

You are correct about loading it. I was hoping to do as much as possible while there is room to work...then revisit it at actual ride height with everything ***embled and in place. Hoping to heat and bend those arms prior to reinstalling the aluminum backing plates, etc. to save some work.

 

We usually work out the ride ht. based on weight and then clamp or strap it down. You don't need the engine and all that in the way.

 

IMHO the answer to the original question: doesn't make much difference. The arc created by the steering arm in its motion left to right is still there either way. I am NOT an engineer by no means, so maybe an automotive engineer that deals with the subject should weigh in.

 

Another question pertaining to the pitman arm as this moves forward...

Once I end up with a position for the steering arms, should the pitman also match?

Should the rod end elevation be close to allow the rod to be as level as possible?

Does the pitman rod end need to be placed at the same angle as the steering? This doesn't seem logical as the angle will change as the pitman moves through its arc...unless it is flat to begin with.

Thanks for the help so far.

 

Ideally, the arms on the spindles should be parallel with the pitman arm on your steering box, but even that's not requisite. It also doesn't matter if they're parallel to the ground or not. The ball in the tie-rod end will allow for angular mis-alignment between the three joints.

 

wouldn't they be fine the way Ford made them? I would think the after market bolt on arms you have would use the same anlges as stock. Maybe compare to a stock spindle?

 

Death Wobble - speedway tie rod may be suspect - Post #181:

"I have been going over this tie rod bending bit and the only thing that I can come up with is, as you said the tie rod is not bending, but it has a slight bowing. That is from the force applied to the rod not being on the same plane as the reactionary force and the bowing the tie rod tries to find a neutral point. This has more to do with the steering arm angle side to side than the tube itself. The steering arms should have the tie rod bolt heads perpendicular to the ground not a an angle."

This is my problem. **** is really reputable guy on here and I think I can take his comments to the bank. This has me a little confused since there is some variability in answers from other experts.

Tom<!-- / message --><!-- edit note -->

 

Well, read through the wobble threads a bit more. There are people hinting around about 7-8 caster being too much. It also causes the weak tie rods to flex as well as making your steering arms not parallel to the ground.

Each year the wobble threads seem to go a little deeper into finding the real cause. It would be great if someday there is spec sheet to build a I beam suspension the best way.

I went through my old Motors manuals from the 30s, looking for caster specs on a few I beam cars last week. There were some at 3 as well as a Nash at high 6's. I was just trying to see if all solid axle cars had excessive caster.

I am going to try 3 on mine. If I have to eat crow, that's Ok

 

Parallel with kingpin c/l. That is the axis they are cir***venting.

Imagine, if you will:

Suppose the axle is set in extreme positive caster, say...26 degrees. Now, what kind of smooth arc would the tie rod ends move in if inclined 26 degrees off center? (or parallel with the ground)
This exaggerated example can be best understood after reading Elliott's principle.
He tied his bathroom doors together (both were hinged from a west wall) at different open intervals, discovering 'toe-out on turns'. (Horseless carriages had rigid front axles then) German engineer Ackermann unduly ******ed credit for this principle, but it was Elliott, the American, who discovered the phenomenon. His trig went further, stipulating the necessity to have clevis joints turn in the same plane when applying caster.
Ford tie rod ends will mask the inevitable bind when turning, but the tie rod will 'roll', as it gets out of phase with the inclined king pins, if spindle arms are not parallel with their centerline. (simple physics)
King pin inclination is not relevant, as left-and-right turns are limited to 25 degrees +/-.

 

Going to have to agree with A****er on this one. The physics seems right on that explanation. As far as my own experience goes, I am running 7 degrees caster, tie rod parallel to the 7 degrees, cross steer and never had an ounce of death wobble. And that was true when I had a center bearing on the axle for location and is true now with the despised by some dead perch.

I have also had cars in my shop with them set perpendicular to the ground like Spadarro says and they worked fine as well.

 

1) Leave the arms where they are..The tie rod ends will go through less angular change, lock to lock..
2) CASTER: In a reactively lite car I feel 6° is enough, Way back I ran 2° in my g***er so it didn't take two men and me to turn the steering wheel at slow speeds..3000# car..It tracked [tracks, still does fine] with no problems whether at 1 mph or 110 mph and I have PS now.....
3) Tie Rod Ends/Tie Rod [tube]..Important is that the rod is straight, if in an application the tie rod has to have a bend(s) for clearance then it will flex because of, and at the bends, and maybe even bending into a "new" shape....factual for me!!
4) Drag Link...Important that at ride height the drag link is parallel to the tie rod, not overly critical fore and aft but in up/down plane...Obtained by steering box mounting height and/or bending the steering arm, your choice [kidding] to make stud perpendicular to ground or same angle as tie rod ends..Just aesthetics..

 

Seb, can you explain the old standard of setting these I beams at 7-8, when if you said 2 was enough...and the car still tracked at all speeds..?

Just wondering why the " correct way" is so much more caster?? Is it possibly just to get more road feel (steering resistance) ?

I have never understood why it is needed. We all run wider tires at the rear that have more rolling resistance than skinny fronts, so it should track fine even with minimal caster (in theory ). I am 90% convinced most hamb death wobble cars can be fixed with a caster change. Yes, other things can be done to mask it like beefing components like a tie rod, but I feel the real culprit is caster..

 

Hi guys let me clarify this a little. The tie rod p***es forces thu the tie rod and ball end. As the steering arms tip further rearward due to increased caster this creates an upward swing of the steering arm as the spindle rotates around the king pin inclination axis. Providing you have rotational clearance in the tie rod end and space between the tie rod and the longitudinal locating rods nothing obstructs the steering. Just like your picture. Perfectly fine.

However using the straight steering arms downward or bending arms to obtain additional tie rod clearence for wishbones poses problems. Downward bending creates even more bind in the tie rod link because it moves the steering radius parallel to the king pin angle and binds up the tie rod end as the steering radius turns tightly around the king pin axis.

My suggestion was to to bend the tie rod end mount more perpendicular to the king pin axis,this moves the steering radius away from the king pin axis and increasing the operating radius of the tie rod with out binding the rod end.

What you have ***embled is perfectly ok. See how the taper tie rod holes are almost perpendicular to the ground and the king pin.

My concern would be that you have squared the installation to the ch***is after ***embly. Good luck, you are on the way to the rod run.

 

****, it takes me awhile to understand some of the post... Does the above sentence mean that the tie rod ball end is twisting more than the ball socket was able to allow?

I think that's what you mean?

 

Thanks to ALL of you guys for the EXCELLENT information. Looks like we have some consensus (and a lot of logic) on the steering arms. Jury is still out on the caster angle, however.

I bought a crossmember from So Cal in Colorado Springs that had 7* built into it when I started on the frame several years ago. All the frame mods have still resulted in 7* (actually 6.8* on each side). I may have room to play by milling an angle spacer (spring to x-member) if it doesn't work out. Hate those cheesy looking adjustable spring perches, but may serve as last resort. However, need to try it as is first before fixing something that may not really be broken.

**** - Got your message about squaring the wheel centers loud and clear! In this and in other postings you have done, you have emphasized that many times since it is so important. I have really valued that and other advise you have given.
I was really careful to keep the frame square when I built it. I have since used the reference marks on the frame to true the suspension. I think I am pretty close using that method...but have definite plans to see a first rate alignment shop north of me as soon as it rolls. I would feel a lot better about having somebody with a known level and square alignment rack be able to dial it in perfectly...with the right tools and knowledge. These guys actually understand these cars...so consider myself lucky.

Don't know how this stuff was accomplished CORRECTLY before the HAMB!

Tom

 

Update:

Want to let you know where I ended up and the result. Turns out that my digital level or king pin reference was off a bit. Actually ended up with close to 8* of castor when I took it in to an alignment shop in Loveland, CO that actually understands these suspensions. He asked me up front where I wanted it to be. He said 4-6*. We settled on 6.

Driving it up to him at 8* was just fine. No wobble anywhere at a variety of speeds. That included a good hit in a pothole that I couldn't avoid. No bump steer with the steering arms at the angle depicted in the previous photos coming out of the hole. I didn't notice any real difference at 6* on the way home. It simply runs and drives nice either way!

BTW- I am using Speedway 7/8" tie rods. Using same for the Panhard rod. No flex that I can see. This is contrary to some discussion in previous threads.

Hope that helps with this ongoing discussion.

 

I try to read everyone's setup, so thanks for the update.

Did your alignment guy explain why he wanted a lower number on the caster?

I am going in at 3, and if I ever get to drive it, I don't know what to expect More caster sure strains a lot of parts from watching mine steer in the shop at 10 and then 8 degrees...not moving. It behaves nice at 3, but that's just sitting there.

 

You know, not sure why he suggested lower. He was adamant about not going over 7.

Funny thing, I had a very interesting discussion with a well known and respected Loveland builder while at the Gunnison car show on Saturday. It was one of his guys that gave me the alignment referral in the first place. He said 7* was a minimum and preferred 9* in some cases! Yet he uses this Loveland alignment place. Wonder what his cars come back dialed in at??? Probably 7* straight up!

Anyway, the builder pointed out that you will never see a top fuel dragster have death wobble going forward at >20*. Now that is food for thought. The only problem with 20* is going in reverse. Not supposed to do that in a dragster unless you make a mistake. Pay twice!

Tom

 

Wrong rational on caster. You do not need any exceptionally large caster angle to make your car track better. Based upon the scrub angle of the wheel and the increased width of tires being run actually decreasing the caster is better for operation than increasing it. If you refer to the original specifications for a starting point you must take into consideration the tire being used and the wheel design you will see this setting is for a narrow 4" wide tire on an on center rim. As you increase the tire width or rim offfset you increase the contact patch, which increases the load,which increases the scrub, which increases the steer effort or reach a point that the caster trail angle may excite that over caster supermarket cart style shhhake.

 

^ The above info backs up what happened to an old 50s built roadster I bought in 1970. The seller took me for a wild test ride over nasty city streets with no problems.

I bought the car, installed 6" wide mags on the front, and had my first taste of true death wobble.

After 40 years, I still read every word on front ends and settings.

 

****:
This makes sense, as usual. So I take it that the tiny motorcycle (bicycle) tire contact patch used on the dragster was pretty caster angle becomes more critical as the load (tire to road friction?) increases. Must have gotten really hairy in the late 70's when wide fronts came in vogue.

 

Old thread resurrected!

I'd say yes, straight ahead ideally, but probably more important to have the box centered on the slightly stiff section for driving dead ahead. If this means the pitman isn't dead straight then so be it. Slightly different turning shouldn't make much difference in normal use.

Chris

 

thanks ............... got it fixed ............